Cisco Broadband Wireless Gateway 1.2 for IOS Release 12.4(15)XL3

This feature module explains and discusses the feature set for the Cisco Broadband Wireless Gateway (BWG). Additionally, this feature module explains how to configure those features, and provides sample configurations when appropriate.

This chapter contains information on the following features:

•Ethernet Convergence Sublayer (CS)

–Ethernet CS—Data and Control Both on R6

•CPE Management

–AAA Access for Unauthenticated Subscriber

•Support for MS/Host with Statically Assigned IP

–IP CS

•EAP Authentication

–Network Admission of an Authenticated User

–Support of Un-Authenticated User

–Configuring Authentication

•Security Key Exchange

•IP Address Allocation Using DHCP

–Configuring IP Address Allocation

–Multiple Host Support

–Support of Multiple Hosts Behind a SS

–DHCP Option 82

•Service Flow Creation and Management

–Service Flows

–Multiple Service Flow Creation

–Configuring BWG Service

–Mapping of Service Flows to DiffServ Classes

–Configuring Service Flows on the BWG

–Configuring Service Flow Packet Classification

•QoS Support

–Configuring QoS

•User Group Management

–Idle Timer Support

–Session Timer Support

•AAA Accounting Start-Stop-Interim

–Host Based Accounting New

–Configuring AAA Accounting

•Handoffs

–Uncontrolled Handoff

–Controlled Handoff

•Keepalive Support for R6 Interface

–Configuring Keepalive

•Session Redundancy

–BWG Session Redundancy and High Availability Infrastructure

–Subscriber Management

–DHCP and AAA

–IOS AAA is not HA-aware at the moment, so the sync of AAA-related information is part of the session replication.

–Dynamic Synchronization

–Configuring Session Redundancy

–Authentication

–Accounting

–Subscriber IP Address

–QoS

–Statistics and Counters

–BWG Load Balancing

–Data Path and GRE

–Version Control

–Limitations

–Switchover

•BWG Load Balancing

–BWG Selection

–Modes of Operation

–Configuring Load Balancing

–Configuring Cisco IOS SLB for Load Balancing

–Configuring the BWG for Load Balancing

•Configuring SNMP on the BWG

•Mobile to Mobile Traffic Steering New

•CAR/AAA Configuration New

•MIB Support

–Verifying MIB Support

•Restrictions

•Features Not Supported

Ethernet Convergence Sublayer (CS)

The Wimax Ethernet Convergence Sublayer (CS) allows a WiMAX network to provide Ethernet Service directly to customers. In comparison with the IP CS, it allows IEEE 802.3 frames (carrying higher layer IP datagrams) to be encapsulated in the 802.16 PDUs. In the Cisco BWG 1.1 release, only two options of Ethernet CS are implemented: BS local switch (enterprise customers), and L2-L3 bridging conversion (residential customers),

Note L2-L2 bridging on the BWG is not currently available.

As a part of Ethernet CS requirement, the BWG will support statically assigned IP addresses for the CPE/MS/host. This includes the following sub-features for the BWG:

•Enforce a maximum number (8) of active hosts per subscriber/CPE

•Auto-learning of L2/L3 details of the hosts through ARP, or any uplink packet from the host.

•Static host IP verification with Framed-Route from AAA

•A mechanism to age/bump out the idle host.

Ethernet Convergence Sublayer (CS)—R6 Control Only

In the Cisco 12.4(15)XL1 release, the WiMAX R6 interface between the BWG and Base Station (BS) is used for signaling only; the BWG instructs the BS to switch traffic locally. In the absence of GRE encapsulation, the BWG does not receive the bearer traffic from the BS. Instead, the BS must switch or forward the ethernet frames to an externally connected L2 Switch.

Note The R6 Control Plane Only feature should only be used for the Ethernet CS in the Cisco BWG R1.1 release.

Since the data packets no longer go through the BWG in this configuration, the BWG needs the following adjustments:

•Session Idle Timer: The BWG needs to ensure that a session remains open even if no packet is received or sent for the subscriber.

•When AAA sets the session timer to 0, it indicates it is infinite.

•Accounting: The BWG only performs "Accounting Start" and "Accounting Stop", which corresponds to the service flow creation and deletion. Interim periodic accounting updates are not performed since BWG does not receive bearer traffic in this scenario.

In cases where the BWG does not receive the de-registration request from BS, the absolute session timer is used to de-register the MS on the BWG in order to remove hanging sessions.

The following steps illustrate the sequence of events for the R6 Control Only feature:

Step 1 SS sends a registration message to the BS. The BS forwards it to the BWG.

Step 2 The BWG asks for profile from the AAA server with user_name MSID@proxy-realm. Proxy-realm is configured in the user-group.

Step 3 AAA sends the SLA profile back with the following information:

–SS is identified as a business based on the SLA profile (which is configured as encap-type none on the BWG); in this case that traffic is locally switched at the BS identifies this as an Enterprise.

–The VLAN ID (unique for every business SS connected to same BS). For example, the VLAN ID = 250.

Step 4 The BWG sends the Service Flow profiles info to the BS, along with VLAN ID and the Packet Classifications rules. The BS further sends the uplink Packet Classification rules to the SS.

Step 5 Upstream traffic is initiated: this assumes that the CPE router will send uplink .1q tagged traffic, with following VLANs:

–VLAN 10 (Sales)

–VLAN 20 (Voice)

Step 6 If the PCR is such that the SS will put traffic from VLAN 10 into Service Flow 1, this service flow type is BE. If the PCR is such that the SS will put traffic from VLAN 20 into Service Flow 2, this service flow type is UGS. The SS sends traffic to the BS.

Step 7 The BS assigns another .1q tag on incoming traffic for enterprise x (for example VLAN ID = 250). The inner tag is left unchanged. Traffic is switched to the L2 network, and does not go to the BWG.

Step 8 For downstream traffic, the following occurs:

–The BS receives traffic from the L2 switched network.

–Enterprise traffic does not come through BWG.

–The PCR will tell the BS on what SF traffic has to be sent.

–The BS strips the entire outer tag and forwards the remaining packet traffic over the air by SF1 (BE) or SF2 (UGS).

Step 9 The SS receives the traffic and forwards it to the switch. The inner tag is left unchanged.

Additionally, in this scenario the BS, rather than the BWG, terminates the uplink/downlink service flows. The BWG sends the downlink classifiers to the BS so that the BS can choose a proper downlink service flow for a packet. The BS needs the downlink classifiers to select the 802.16e air link connection ID/service flow. The BWG also signals the BS which VLAN tag to use for uplink traffic.

While the BWG design allows the flexibility to perform BS local switching on a flow-by-flow basis, for Release 1.1 all service flows should be configured to be either collectively BS-local switched, or BWG switched for a particular subscriber.

Configuring R6 Control Only

This section provides information on how to configure the R6 Control Only feature on the Cisco BWG. To enable R6 Control Only, perform the following tasks:


	Command	Purpose
Step 1	router(config)# wimax agw sla profile gold	Specifies the Service level agreement (SLA) on the BWG. The BWG will enforce a limit for the number of service flows to 4 for each SLA profile. Attempting to exceed the limit will result in a failure.
Step 2	router(config)# service-flow pre-defined isf profile isf encap-type none vlan 10	Specifies the initial service flow should be BS local-switched with a VLAN ID set to 10.
Step 3	service-flow pre-defined secondary profile sec1 encap-type none vlan 10	The BWG controls the BS's local switching through Data Path Encapsulation Type (NONE) and Data Path ID (Priority + VLAN ID) in the R6 DP Registration Request message. Note that the VLAN ID defined here could be overwritten from AAA.

Note For BWG Release 1.1, the same vlan should be configured in the same SLA profile.

Note When the vlan is downloaded from AAA, it will overwrite the vlans locally configured for all service flows.

The BWG controls the BS's local switching through Data Path Encapsulation Type (NONE) and Data Path ID (Priority + VLAN ID) in the R6 DP Registration Request message. Note that the VLAN ID defined here could be overwritten from AAA. The VLAN Priority (the 3 most significant bits in VLAN tag) comes from DSCP/Precedence defined for the service flow. If DSCP/Precedence is not locally defined, it is calculated based on WiMAX QoS Data Delivery Service Type used for the service flow.

Ethernet CS—Data and Control Both on R6

To align with the WiMAX Forum NWG standard, Cisco's R6 interface supports Ethernet CS with data and control. As noted earlier, only the L2-L3 bridging option for the BWG is supported in this release.

The L2 uplink traffic comes from the host behind the CPE/MS, and these packets are encapsulated 802.16 PDUs and sent to the BS by the CPE through the R1 interface. The BS then encapsulates the Ethernet frame into the GRE packet (the GRE tunnel was established during R6 signaling exchange), and sends it to the BWG. The BWG receives the GRE packet through the R6 data path. After stripping the GRE header and L2 header, the inner IP packet is forwarded to a proper interface configured in the intended VRF.

When the BWG receives the downlink packets, it finds the related host where the L2 information related to the particular host is saved. The L2 information, along with the L3 information carried in the packet, is used to compare with the configured classifiers. As a result, a proper service flow is selected. Once a service flow is selected, the saved L2 information for the host is used to encapsulate the received IP packets.

The host's L2/L3 information is dynamically learned by the BWG through the following mechanisms:

•DHCP procedure from host

•ARP Request from host

•Any uplink packet from host

VLAN to VRF Mapping for L2-L3 Bridging

This feature allows that the uplink L2 traffic with a particular VLAN ID is mapped to a VRF routing domain to forward the IP packets. On the other hand, the downlink IP traffic from a particular VRF will be sent to the MS encapsulated with the same VLAN ID. Note that BWG is designed to support at most one VLAN ID for each host behind MS.

Packet Fragmentation Handling

The virtual template interface on the BWG must be configured with a MTU so that no GRE fragmentation is needed for the R6 data path. The preferable MTU value is less than 1440.

For downlink packets larger than the MTU configured for the virtual template interface, they will be fragmented by IOS, and in doing so, IOS expects to clear the DF bits in the original packets. The BWG receives two IP packets in this scenario. The two IP packets are GRE encapsulated separately, and sent to the BS. The BS transparently passes the two packets to the host where they are assembled and delivered to an application.

For a large uplink packet, the BS clears the DF bits, fragments it into two packets, and sends them to the BWG. The BWG does not reassemble the packets, but forwards them separately.

DHCP Option 82 Enhancement

In order to allow the BWG to build the L2 header for downlink DHCP packets, the entire L2 header is coded in the Option 82, which is reflected back from the DHCP server. This sub-option only applies between the BWG and DHCP server.

DSCP Calculation/Marking/Signaling

For downlink traffic, the DSCP marking is performed by the BWG. The outer IP DSCP value is obtained in the order of precedence from:

•DSCP/Precedence set for the flow.

•Calculated from SF's Data Delivery Service Type as shown in the following table.

Table 2-1
WiMAX QoS	DSCP	Comments
UGS	46
ERT-VR	38
RT-VR	30
NRT-VR	22
BE	0

Note The inner IP's DSCP value is no longer used for marking the outer IP's DSCP.

Note The inner IP value is also marked.

Note The SF QoS to DSCP mapping table is used only when the DSCP is not configured for the SF.

For uplink traffic, the BWG obtains the DSCP value in the same way as for the downlink service flow. The uplink DSCP value is signaled to the BS in the Data Path Info TLV.

Consider that DSCP marking of inner user (uplink) packets cannot be trusted; therefore, the same uplink DSCP value signaled to BS for a service flow is also used to re-mark the R3 uplink packets.

Ethernet Frame Support

The BWG can support Ethernet II, LLC (802.2) and Ethernet SNAP frame types for different hosts. However, one particular host must use the same frame type during its session. In other words, one particular host can only transmit packets with the same Ethernet frame type.

Ethernet VLAN Support

Ethernet packets with a VLAN tag (specifically 802.1Q and Q-in-Q) are also supported.

Ethernet FCS (CRC)

There should be no CRC for both uplink and downlink packets over GRE towards the BWG.

Limitations

The following CS Ethernet limitations exist in Cisco BWG release 1.1

•Layer 2 broadcast/multicast packets from the MS other than ARP and DHCP are dropped at the BWG.

CPE Management

The CPE Management feature allows the BWG to use AAA to centralize the management of subscribers/CPEs for the overall Cisco WiMax solution. Considering the potential congestion and multiple AAA proxies in a real deployment, it can take up to 10 seconds to recieve the RADIUS Access Accept message from AAA. Therefore, the related R6 protocol state machine should be designed to tolerate this AAA response delay.

The unauthenticated CPE management function has been moved to AAA and the BWG. Specifically, it includes the following features:

•User Domain Group Re-assignment

•Service-Level-Agreement (SLA)

•VLAN ID

•Mobile Capability (non-nomadic with a home BS list, and nomadic)

•Static IP Allowed (### whether static IP is allowed for the CPE)

•CPE Type

•CPE Settings

•CPE Auto-Provisioning

AAA Access for Unauthenticated Subscriber

For Base station/CPE that does not support EAP-based authentication, the BWG provides a PPP/PAP method of authentication using RADIUS. Such CPE generally get classified as Unauthenticated CPE. And for un-authenticated users, we do not get the user name from the CPE.

In this case, the user name, realm and password will be formed based on the following CLI:

wimax agw user group-list wimax

 user-group unauthenticated

  aaa authentication method-list xxxx

  proxy realm sprint.com passwd ciscoway

  sla profile-name silver

Note The aaa authentication method-list xxxx command indicates if the RADIUS Access Request is initiated from the BWG for the group. If the CLI is not configured, AAA query is not required. The respective authentication method list is type PPP, which enables the BWG to perform PAP-based authentication.

Note Reauthentication for PAP users is not supported. The session will be de-registered if reauthentication is attempted by a CPE/MS.

Note The proxy realm sprint.com password ciscoway command instructs the BWG how to populate the RADIUS Access Request message. If configured, the user name will be constructed as mac@realm (for example, mac @sprint.com). If the realm is not configured, the user name will be mac. If not configured, cisco is used as the password. The method list configured using aaa authentication method-list xxxx is not used by the BWG in Access-Requests, since PAP authentication uses default method list configured globally by the aaa authentication ppp default command.

Note These two CLIs are applicable for other user groups (EAP users) as well. However, configuring proxy-realm for EAP users serve no purpose.

The reply from the AAA server contains the user's real domain name, which is used for selecting a local user group. The above scheme should not break EAP-authenticated users. In other words, the BWG should allow EAP and non-EAP authenticated users to coexist. For authenticated users, the user name is acquired from CPE through EAP identity request. EAP uses NAI in an Access request to the AAA. If the response from the AAA includes the Service Level Agreement (SLA) Profile Name and the User Domain Name for EAP users, the result from the AAA will override those determined earlier.

New AAA Attributes

To support the CPE management, the following new AAA attributes have been introduced. These new attributes may be returned in the RADIUS Access-Accept message. These attributes are all optional, and are AVPs under cisco_vsa.

Table 2-2 New AAA Attributes
Attributes	Format/Length	Comment
User Domain Name	String/253	If returned, the subscriber will be re-assigned to the corresponding user group.
SLA Profile Name	String/253	If returned, the SLA profile corresponding to this name will overwrite the one locally defined in the user group in the BWG.
VLAN ID	Integer/2	Used to tag the L2 traffic; Overwrite SF's local definition. In case of BS local switch, signaled to BS. Note This attribute is applicable to R6 control only sessions.
CPE Type	String/253	For diagnostics, not used by BWG except being displayed by: "show wim agw sub" CLI
CPE Mobility	Integer/2	Defines how much mobility the CPE can be: 0 - non-nomadic with a Home BS List 1 - nomadic The default is nomadic.
CPE Settings	Integer/4	These CPE toggle settings are configured in AAA and downloaded into the BWG. The BWG will further use the R6 control protocol to signal BS, where BS further passes the info to the CPE. - bit 31: IngressACL Toggle: Once enabled, the CPE will block some uplink traffic from hosts whose source IP address is not learned by the CPE. - bit 30: Broadcast Filtering Toggle: Once enabled, the CPE will block the uplink broadcast traffic. - bit 29: Rate Limiting Toggle: Once enabled, the CPE will impose rate limiting for uplink traffic such as ICMP and ARP. - bit 0-28: reserved, set to 0 Refer to Cisco R6 Specification
BS List	Binary Hex/253 BSID1:BSID2	This list will be interpreted as a Home BS list if the CPE Mobile Capability equals to "non-nomadic". The BSID could be an IPv4 address or in the format of 802.16 (6 bytes) BSID1 = 1A.01.23.BC
Static IP Allowed	Integer/4	Used to indicate whether BWG is allowed to learn the CPE/Host's static IP address. This is mainly for security reason: 0 - not allowed 1 - allowed In the absence of this attribute, the default is not allowed.

Note The above AAA attributes are intended for PAP users, but they should work equally well for EAP users.

Configuring the SLA Profile

To configure the Service Level Agreement on the BWG, perform the following tasks"


	Command	Purpose
Step 1	router(config)# wimax agw sla profile eth_vlan_pri_sla	Configure the Service level agreement (SLA) on the BWG. The SLA profile includes all the flows. The BWG will enforce a limit for the number of service flows to 4 for each SLA profile. Attempting to exceed the limit will result in a failure. For Cisco BWG Release 1.1, the same vlan should be configured in the same SLA profile. Different service flows get listed under one SLA profile. You can associate an SLA with a user-group by configuring subcommand sla profile profile name. Provisioning the SLA allows you to better manage the service flows.
Step 2	router(config)# service-flow pre-defined isf profile dfault_vlan_sf service-flow pre-defined secondary 1 profile vlan_pri_01_sf service-flow pre-defined secondary 2 profile vlan_pri_02_sf service-flow pre-defined secondary 3 profile vlan_pri_03_sf	Different service flows get listed under one SLA profile.
Step 3	router(config)#wimax agw user group-list wimax user-group unauthenticated aaa accounting method-list agw sla profile-name silver	Configures the User group list on the BWG. There can be only one user group list allowed on a single processor of the BWG. The no version of command will remove the user group list. This will create a user group list sub configuration mode to create multiple user groups under the user-group list created.

In the above configuration, the user group's SLA profile acts as a default. The AAA return SLA profile name should take precedence.

Multiple SLA Profile Support Per Subscriber

Prior to this release, SLA profile configuration on the BWG allowed WiMax service providers who defined the service packages efficiently to categorize service offerings (flow types) in a reasonable number of profiles.

For example, the following flows (flow-voice, flow-data, flow-video, flow-hd-video, flow-premium-voice, flow-premium-data) could be defined in 2 packages and sold to subscribers on a package basis.

SLA-regular

•flow-voice,

•flow-data

SLA-premium

•flow-premium-voice,

•flow-premium-data

•flow-hd-video

However, if service providers wanted to offer services in all possible combinations from the above list of flows, they would have to configure as many SLA profiles on BWG.

This feature allows service providers to configure SLA profiles similar to following and package the services to customers in any desirable combination.

SLA-regular data

•Flow-data

SLA-regular voice

•Flow-voice,

SLA premium video

•Flow-hd-video

SLA-premium data flow

•Flow-premium-data

The BWG supports flow creation based on multiple SLA profile names received from AAA. This is in addition to the existing support for a single SLA profile name. AAA can send a list of SLA profile names, separated either by comma, space or semicolon.

The BWG will parse the list to choose valid, configured SLA profiles to create the service flows for session.

The BWG uses the following sequence of events to create the flows:

•BWG selects only configured SLA profile names from list.

•BWG selects only the unique flows from across the list of SLA profile names. For example, it takes "Union" across all the flows defined under received SLA profile names (with the exception of ISF).

•The current implementation needs only one ISF for successful flow creation. As a result, the BWG selects the ISF based on the order of SLA profile name in list of SLA profile names received from AAA. Even if different ISF profiles are configured for SLA profiles received, it selects the ISF from the first valid, configured SLA profile from the received list.

•The BWG discards all the remaining SLA profiles and SF profiles if the maximum allowed service flows limit is reached.

•The BWG does not check the validity (for example, if SF is configured correctly or not) of the SF under the SLA profile at the time it parses the list received from AAA. As a result, if the SF is found to be invalid or un-configured when the BWG is about to open that SF, then that SF gets dropped and BWG continues with rest of the SF profiles.

•If ISF is not present in SLA profiles coming from the AAA, the session is cleared.

Here is an example of the configuration:

wimax agw sla profile silver

     service-flow pre-defined isf profile isf

wimax agw sla profile platinum

      service-flow pre-defined secondary 1 profile sec4

wimax agw sla profile gold

      service-flow pre-defined isf profile isf2

      service-flow pre-defined secondary 1 profile sec

      service-flow pre-defined secondary 2 profile sec2

      service-flow pre-defined secondary 3 profile sec3

If the SLA list received from AAA is "silver, gold, or platinum" then the session's SLA profile name is set to "silver, or gold", and the following four flows are created on the BWG:

•isf

•sec4

•sec

•sec2

If the above configuration SLA list received from AAA is "platinum, unconfigured, gold", then the profile name of the session is set to "platinum, gold", and the following four flows are created:

•isf2

•sec

•sec2

•sec3

The "unconfigured" SLA is discarded by the BWG.

Here is another example:

wimax agw sla profile silver

     service-flow pre-defined isf profile isf

wimax agw sla profile platinum

      service-flow pre-defined secondary 1 profile sec

wimax agw sla profile gold

      service-flow pre-defined isf profile isf2

      service-flow pre-defined secondary 1 profile sec

      service-flow pre-defined secondary 2 profile sec2

      service-flow pre-defined secondary 3 profile sec3

If the SLA list received from AAA is "platinum, unconfigured, gold", then the profile name of session will get set to "platinum, gold", and the following four flows are created:

•isf2

•sec (based on the order in which the SLAs were received, this flow was taken from SLA platinum)

•sec2

•sec3

The "unconfigured" SLA is discarded by the BWG.

In the absence of SLA from AAA, the BWG creates flows according to the SLA profile defined under the session's user group. The BWG still supports the single SLA profile sent by AAA.

User Auto-Provisioning

There are occasions when a user is admitted into the network for a short while even if AAA does not have provisioning for him/her. To enable this feature, the related unauthenticated group should be properly configured. When enabled, the session timer in the user group should be configured to a small value so that the user's free use of the network is limited.

To configure auto-provisioning, perform the following task:


	Command	Purpose
Step 1	router(config)# wimax agw user group-list wimax user-group unauthenticated aaa accounting method-list agw sla profile-name silver user auto-provisioning timeout session 600	Enables users to be auto-provisioned into the network for a configurable time even when AAA does not have provisioning for them.

Note Auto-provisioning is not supported for EAP users. It does not take effect when configured with any user group other than the unauthenticated.

Note Auto-provisioning for hosts with static IP and IPCS is not supported.

Support for MS/Host with Statically Assigned IP

The BWG's DHCP mechanism for Ethernet CS is similar to that of IPCS except for an additional sub-option (L2 header) for option 82. Through the DHCP procedure, the BWG is able to capture the host's L2 header (including frame type) and IP address. In addition to the DHCP mechanism, the BWG supports the MS/host with a statically assigned IP address.

The static IP address is handled differently depending if IPCS or Ethernet CS is used.

IP CS

Authenticated Subscriber

For authenticated subscribers, the Framed-Route from AAA response can be used for downlink traffic routing. This feature is already supported in the BWG.

The BWG learns about static hosts in IP CS case through uplink data packets. The BWG does not have any L2 header information, so these static hosts are created without MAC IDs. The aging mechanism described below in the Ethernet CS section also applies to IP CS static hosts.

Note Unauthenticated subscribers are not supported.

Ethernet CS

There are two mechanisms for the BWG to learn the L2 header info and IP address from the statically configured host. The BWG creates its host entry (indexed by table ID—VRF and IP address) and L3 routing entry. The static hosts created in the BWG are limited to 8 active hosts per subscribers. However, a 9th host can be accepted if one of the existing static hosts' idle periods has exceeded a threshold value. In this case, the static host which has been idle the longest is bumped out by the new arrival. The host idle threshold is 75% of session idle timer. A static idle host is removed in the BWG only when a new host is detected by the BWG. DHCP hosts are not aged out.

All of the static IP that are learned are verified with the Framed-Route from the AAA. Currently the BWG supports one framed-route per CPE.

Note You should not disable the route aggregation feature for the user-group. This will prevent too many static host routes to be created or deleted from the routing table, which degrades the performance.

ARP Request from Host

The BWG can always intercept the ARP request packet to learn the host's IP and L2 header info (including frame type). The creation of a static host is subjected to the limits of active hosts per subscriber. If the BWG cannot admit the host, the ARP request will not receive a reply.

The BWG handles ARP packets similar to those for DHCP messages. The ARP reply packet is returned to the same service flow where the request originated. The BWG's MAC address (interface on which the ARP request was received) is used in the ARP reply message to the MS.

The BWG also implements an ARP-rate processing limiting feature to prevent itself from being overwhelmed. ARP packets are dropped if their rate of arrival exceeds what the BWG can handle. Currently the throttling mechanism on the BWG allows one upstream ARP request every 5 seconds.

To be a true ARP proxy, the BWG must be able to intercept a pass-through ARP request packet. These packets have a Target Protocol Address (TPA) different from BWG's IP. In the ARP reply packet, the TPA in the request packet is used.

Uplink Packet from Host

When an uplink packet is received by the BWG without its host entry in the Cisco Express Forwarding (CEF) path, it is rerouted to the process path where it is processed. As a result, a new host may be created. If the host cannot be created (subject to the 8 active host limit), the packet is silently dropped.

The BWG implements a throttle mechanism to prevent rerouting of the packets to the process path from overwhelming the BWG. Currently the throttling mechanism on the BWG reroutes 1 packet every 5 seconds.

Limitations

•A host that was bumped out of the network is not able to receive downlink traffic without first sending some uplink traffic. When this occurs, it indicates that the CPE actually has more than 8 hosts behind it.

•Upstream gratuitous ARPs are dropped by the BWG, and the BWG does not learn from these packets.

Other Enhancements

To support the Cisco BWG Release 1.1 and above features, the BWG is enhanced in the areas of the R6 Protocol, MIB, statistics, SR and CLI.

R6 Protocol Enhancement

The existing R6 protocol is enhanced to accommodate the Ethernet CS requirements.

R6 Attachment Request

CS Capability

The CS capability in the Registration context in the message must be set to the proper value to indicate Ethernet CS by the BS or the BS simulator.

Note The CS Capability included in this message can indicate a single CS type, or a set of CS types with a bitmap supported by the MS. In any case, it shows the MS's capabilities. Please refer to 802.16 for the details CS capability definition.

R6 Attachment Response

This message is sent from the BWG to the BS. The changes to this message are equivalent to the R6 Attachment Request message.

The CS Capability bitmap in this message is encoded to indicate that the BWG supports both IPCS and Ethernet CS.

R6 Data Path Registration Request

This message is sent from the BWG to the BS for normal R6 Data Path setup. The MSINFO TLV contains the following sub-tlvs:

•Anchor GW/DPF ID = IPv4 address of the ASN gateway

•CPE Settings—(optional)

•SF INF

–SFID

–CS Type—Specifies IP CS, Eth CS, or VLAN CS for the flow

–Packet Classification Rule

Classifier Rule Priority

Ethernet Src MAC—(optional) for uplink SF, and are sent for downstream in case of control only scenario

Ethernet Src MAC Mask

Ethernet Dest MAC—(optional) for uplink SF only

Ethernet Dest MAC Mask

EtherType IP

VLAN-ID

VLAN Priority Range

–Data Path Info

Data Path ID—GRE Key or VLAN ID

Data Path Encap. Type

DSCP

The CS Type applies to the particular service flow. It is the intersection between the MS's indicated CS capabilities (in the Attachment Request), as well as the BWG's service flow CLI configuration. If both the CPE and the BWG support both IPCS and Ethernet CS, and the BWG configures both with the same precedence, IPCS is selected.

The Ethernet Src MAC and Ethernet Dest MAC address should be included if they are not configured as any in the corresponding BWG CLI configuration. New tag values conform to the Cisco R6 specification.

The Ethernet and VLAN related classifiers will not be signaled for an IPCS service flow. For Ethernet CS, the classifier VLAN-ID and VLAN Priority Range will be signaled to BS if they are locally configured.

The "Data Path ID" is an existing TLV. The VLAN Priority value (the most significant 3 bits of VLAN Tag) for the VLAN Tag comes from the DSCP/Precedence set for the flow, or derived from the QoS Data Delivery Service configured for the flow.

The "Data Path Encapsulation Type" TLV indicates if the encapsulation type should be used to transport the R6 bearer traffic.

0 = None

1 = GRE (Default)

2 = IP-in-IP

3 = VLAN

The tag value for "Data Path Encap Type" must conform to the Cisco R6 specification. For Ethernet CS R6 control-only scenario, this TLV should be set to "none". When "Data Path Encap. Type" is set to "none", the BS interprets the Data Path ID as a VLAN ID. In its absence, use the R6 data path with GRE to transport the data traffic.

The DSCP values signaled to the BS for uplink SF come from either the BWG locally configured for the SF, or, if it is not present, derived from the QoS Data Delivery Service configured for the flow.

In addition, the ISF Path Registration Request signals the newly defined CPE Settings TLV to the BS if it is available through AAA. The CPE settings are under the MS INFO TLV.

R6 Data Path Registration Response

This message is sent from the BS to the BWG during normal data path setup. The changes to the message are equivalent to the R6 Data Path Registration Request message. All the new TLVs defined for Data Path Registration Request messages are available for the Path Registration Response message.

Other R6 Changes

To be consistent, all the R6 signaling UDP packets have a DSCP value of 0x48. In addition, the UDP checksum is already calculated in Release 1.0 and above.

The BWG enforces a limit for the number of service flows to 4, and the number of active hosts to 8 per subscriber. If you attempt to exceed the limit the BWG will fail.

Note The BWG will not allow more than 4 service flows to be configured per SLA profile.

EAP Authentication

The BWG acts as an EAP relay and is agnostic to the EAP method. EAP transport is done between the BWG and the base station as a control exchange. The base station functions as an EAP-relay, converting from Pair-wise Master Key version 2 (PKMv2) to the EAP messages over to the BWG. The BWG is an EAP pass-through, and any key that generates EAP methods is supported in the system.

PKMv2 is used to perform over-the-air user authentication. PKMv2 transfers EAP over the IEEE 802.16 air interface between the MS and the base station. The base station relays the EAP messages to the Authenticator in the BWG. The AAA client on the Authenticator encapsulates the EAP message in AAA protocol packets, and forwards them through one (or more) AAA proxies to the AAA server in the CSN of the home NSP. In roaming scenarios, one (or more) AAA brokers with AAA proxies may exist between the Authenticator and the AAA server. All AAA sessions always exist between the Authenticator and AAA server, with optional AAA brokers providing a conduit for NAI realm-based routing.

Network Admission of an Authenticated User

The following series of events illustrates how the network admits an authenticated user.

1. The authenticator (in BWG) initiates EAP authentication procedure with MS after receipt of Pre-Attachment-Ack message from the Base Station.

2. The authenticator sends EAP Request/ Identity message over Authentication Relay protocol (AuthRelay-EAP-Transfer) to BS.

3. The BS relays the EAP Request/ Identity payload in the PKMv2 EAP-Transfer/ PKM-RSP message to the MS.

4. The MS responds with EAP Response/ Identity message providing NAI. This message is transferred to BS over PKMv2 EAP-Transfer/ PKM-REQ message.

5. The BS relays EAP payload received in PKMv2 EAP-Transfer to the authenticator over Authentication Relay protocol (AuthRelay-EAP-Transfer message).

6. The EAP payload is forwarded to MS' Home AAA server via Visited AAA server (authenticator analyzes the provided NAI for resolving the Home-AAA server location). Authenticator sends EAP Request/ Identity message over Authentication Relay protocol (AuthRelay-EAP-Transfer) to BS.

7. In order to deliver EAP payload received from BS, to AAA server, authenticator forwards EAP message through the collocated AAA client using RADIUS Access-Request message (EAP payload is encapsulated into RADIUS "EAP message" attribute(s).

8. The EAP authentication process (tunneling EAP authentication method) is performed between the MS and the authentication server through the authenticator in the BWG.

9. The EAP payload returned from the AAA server in a RADIUS Access-Challenge message is transferred to the base station in an AuthRelay-EAP-Transfer message. There may be multiple EAP message exchanges between the EAP supplicant, located at the Mobile Subscriber Station, and the EAP Authentication Server, located at the AAA server.

10. The authenticator sends the Key Change Directive message to the base station to indicate completion of the EAP authentication process. The key is computed by BWG using the Master Secret Key (MSK) it received from AAA (in an Access Accept). The Key Change Directive contains the MSINFO TLV with the AK Context sub-TLV, and also the EAP Payload TLV indicating EAP success.

11. In the case of an authentication failure indication is received from the AAA server the subscriber is de-registered from the network using the Normal Mode Network-Initiated Network Exit procedure.

12. The base station acknowledges receipt of Key Change Directive message with a Key Change Acknowledgement message.

13. The base station sends the result of authentication to the Mobile Subscriber Station using a PKMv2 EAP-Transfer message.

Support of Un-Authenticated User

Support of un-authenticated users is required in the following scenarios, and can be used for pre-paid systems, or emergency calls.

•The Mobile Subscriber (MS) can choose to indicate NULL Authentication. This may be a specific type of MS, such as an MS that is limited to emergency calling. This type of MS will indicate NULL Authentication support in the SBC_REQ. The BS relays this through the NetEntry MS State Change Request to the BWG.

•Based on local policy, the BWG can choose to skip authentication, and allow a subscriber to enter the network.

•When the BWG is configured to enable NULL Authentication using the CLI, any Subscriber Station (SS)/MSS requesting NULL authentication will be mapped to a NULL-AUTH user group. DHCP requests from these SS/MSS will only be sent to the configured DHCP server. This enables the operator to control address allocation to the unauthenticated users, as well as apply any restrictions for such users. In addition, Access Control Lists may be configured that would restrict the traffic from the SS/MSS only to certain destinations.

Cisco's BWG Release 1.1 supports EAP authentication. If the BS/CPE does not support EAP authentication then the CPE gets categorized as unauthenticated. The BWG supports a very basic PAP type of authentication for such CPE where the CPE is authenticated based on its MAC ID and password. The RADIUS server should be pre-configured to provision the CPE.

Configuring AAA to Enable PAP Authentication on BWG

To configure the BWG to enable PPP/PAP authentication, perform the following task in global configuration mode:


	Command	Purpose
Step 1	router(config)# aaa authentication ppp default group {WORD \| radius}	Specifies authentication, authorization, and accounting (AAA) authentication methods for use on serial interfaces that are running PPP.

Here is an example:

router(config)#aaa authentication ppp default group radius

Here is sample show output to verify the configuration

Router#show running-config | include aaa

	aaa new-model

	aaa authentication ppp default group radius

	aaa authorization config-commands

	aaa authorization network default group radius local

	aaa authorization configuration default group radius

	aaa accounting update periodic 1

	aaa accounting network agw start-stop group radius

	aaa session-id common

AAA Access for CPE Using PAP Authentication

For the BWG to initiate PAP Access-Request to RADIUS server for an unauthenticated user-group, perform the following task:


	Command	Purpose
Step 1	router(config-gw-ug)#aaa authentication method-list {WORD \| default}	Indicates if the RADIUS Access Request is to be initiated from the BWG for the user-group. If the command is not configured, the Access-Request is not sent to RADIUS.

Here is an example configuration:

router#wimax agw user group-list wimax

		user-group unauthenticated

		aaa authentication method-list xxx

		sla profile-name gold

		timeout idle 100000

Proxy Realm for CPE Using PAP Authentication

For un-authenticated users, the BWG does not receive the user name from the CPE. In this case, the BWG provide a mechanism to specify proxy realm and password.

To configure the user name, realm and password, perform the following task:


	Command	Purpose
Step 1	router(config-gw-ug)#proxy realm {WORD} password {WORD}	The BWG uses the proxy realm coupled with MACID and password as username and password in a PAP Access-Request. It then sends the request to the RADIUS server.

Here is an example of the configuration:

router#wimax agw user group-list wimax

user-group unauthenticated

aaa authentication method-list agw

proxy realm cisco.com password cisco

sla profile-name gold

timeout idle 100000

In this configuration, the BWG sends and Access-Request to the RADIUS server with username set to MACID@cisco.com and password set to cisco.

If the proxy realm is not configured, the BWG sends an Access-request to the RADIUS server with username set to MACID and password set to cisco (the default password).

Auto-Provisioning for Unauthenticated CPE Using PAP Authentication

Auto-provisioning provides flexibility, and when configured on the BWG, allows CPE the network entry even if AAA does not have provisioning for that CPE.

Note Auto-provisioning is limited to CPE using PAP authentication.

To configure the unauthenticated user group for auto-provisioning, perform the following task:


	Command	Purpose
Step 1	router(config-gw-ug)#user auto-provisioning	Configures an unauthenticated user-group for auto-provisioning. When enabled, the session timer in the user group should be configured to a small value so that the user's free use on the network is limited.

Here is an example of the configuration:

router(config)#wimax agw user group-list wimax

user-group unauthenticated

aaa authentication method-list agw

proxy realm cisco.com password cisco

sla profile-name gold

timeout idle 100000

user auto-provisioning

Configuring Authentication

This section provides information on how to configure authentication and authorization on the Cisco BWG. To enable authenticated calls between the BWG and a subscriber, perform the following tasks on the BWG:

•Configuring AAA for Accounting Types

•Configuring Authorization

•Configuring Authentication

•RADIUS Server

Configuring AAA for Accounting Types

To configure accounting types on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)# aaa session-id {common \| unique}	Specifies either a common or unique session id for different accounting types.
Step 2	router(config)# aaa new-model	Enables the NEW access control commands and functions. (Disables OLD commands.) The no version of this command resumes the old commands and functions.

Configuring Authorization

To configure authorization on the BWG, perform the following task:


	Command	Purpose
Step 1	router(config)# aaa authorization network default group {server-group-name \| radius}	Specifies the server-group to download the configurations from AAA server for a particular authorization list. The no version of this command removes the use of server-group.

Configuring Authentication

To configure authentication on the BWG, perform the following task:


	Command	Purpose
Step 1	router(config)# aaa authentication dot1x {authentication-list-name \| default} group {server-group-name \| radius \| tacacs+}	Specifies the authentication method to be used. The dot1x keyword will be replaced with WiMAX specific keyword.

RADIUS Server

To configure the RADIUS server host on the BWG, perform the following task:


	Command	Purpose
Step 1	router(config)# radius-server host {host-name \| ip-address} {auth-port \| acct-port} key	Configures the RADIUS Server. ip-address of RADIUS server auth-port—UDP port for RADIUS authentication server (default is 1645). acct-port—UDP port for RADIUS accounting server (default is 1646). key—per-server encryption key.

Configuring User Groups

To configure a user group on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)# wimax agw user group-list user-group-list-name	Configures the user group list on the BWG router. There can be only one user group list allowed on a single processor of the BWG. The no version of command removes the user group list. Enabling this command create a user group list sub configuration mode to create multiple user groups under the user-group list created.
Step 2	router(config)# user-group {any \| unauthenticated \| domain domain-name}	Configures the user group under the user group list. This creates a user group sub configuration mode for configuring various parameters of the user group. Three types of user groups are supported: •Domain based user groups - In cases where the user is authenticated, the BWG discovers the user based on the domain name part of the NAI received. The NAI received uses the format userpart@domain. In order to match a user-group abc@cisco.com, you need to configure user-group domain cisco.com and put all the per domain configuration under this user-group. •Any user group - In cases where an authenticated user is not found in a user-group based on the domain, the default behavior is to place those users in this category. For example, if you receive a user with NAI abc@cisco2.com and do not have a user-group domain for cisco2.com, this user will fall into the any user group category. • Un-Authenticated User Group - All un- authenticated users fall into this category of user groups.The no version of command removes the user group. Note For BWG Release 1.0 and above, the presence of user-groups any and unauthenticated is optional.
Step 3	router(config)# aaa {authentication \| accounting} method-list {method-list-name \| default}	Configures the authentication or the accounting method list used for the domain. The no version of the command removes the user group.

Note AAA server group can be linked with the method list configurations so that different AAA servers can be configured, and thereby map to different user-groups.

Verifying the Configuration

The authentication method of a subscriber displays whether the call was authenticated with EAP, or unauthenticated for the respective user group (any, unauthenticated, domain specific).

For an authenticated call, the Auth Policy and AK Context is also displayed.

To verify your authentication configuration, use the following commands:


	Command	Purpose
Step 1	router# show wimax agw subscriber msid	Displays subscriber authentication information.

Configuration Examples

Here is sample output for subscriber information for an unauthenticated call:

Router>sh wimax agw subscriber msid 1000.0003.0000

 Connection time 000:01:05

 Auth policy 0X0(0)

 Subscriber address 2.2.0.9, type IPv4, organization IETF

 Subscriber address method Dynamic, source DHCP relay

 Subscriber address assigned on flow downlink ID 17

 Subscriber address prefix len allocated 32, aggregate 32

 Subscriber address traffic sent 0 packets, 0 bytes

 Subscriber address traffic received 0 packets, 0 bytes

 Subscriber address DHCP XID 2391, server 0.0.0.0, htype 1

 Subscriber address DHCP client ID 1000.0003.0000, length 6

 Subscriber address DHCP Refresh time 86400 seconds

Number of sessions 1

  Session details:

   FSM in state Ready(7) on last event Rx Attach Ack(14)

   Authentication method unauthenticated

Associated user group **unauthenticated**

Signalling address local 2.2.2.2, remote 10.1.1.82

   Signalling UDP port local 2231, remote 2231

   Idle for inbound 00:01:10, outbound 00:01:10

   Ingress Address filtering 0 packets, 0 bytes

   Number of flows 1

    Flow details ISF(0)

     FSM in state SF Ready(4) on last event Up(1)

     Transaction ID used 0X8001(32769)

     Data ID local 0x9(9), remote 0x2(2)

     Data address local 2.2.2.2, remote 10.1.1.82

     Data traffic sent 2 packets, 656 bytes

     Data traffic received 2 packets, 1208 bytes

     Accounting last record sent Interim(3)

     Idle for inbound 00:01:10, outbound 00:01:10

     Service Flow information Downlink:

      Identifier 17

QoS information:

       Data-delivery-service real-time-variable-rate

       Minimum traffic-rate-reserved 4, Maximum latency 1

Here is sample output for subscriber information for an authenticated call:

Router>sh wimax agw subscriber msid 1000.0002.0001MSID 1000.0002.0001

 Connection time 000:01:08

 Auth policy 0X12(18), Single-EAP, CMAC

  AK Ctx method C-MAC(1), Lifetime 65535

  AK Ctx Seq No. AK 0, PMK 0

  AK Ctx C-MAC key count 1

 Number of TIDs 1

 TID Key 10.1.1.82/2.2.2.2/1000.0002.0001

  Peer TID 0X4(4)

    FT MS State Change(9), MT Attachment Request(8)

  Our TID 0x8004(32772)

 Subscriber address 2.2.0.8, type IPv4, organization IETF

 Subscriber address method Dynamic, source DHCP relay

 ....

 Subscriber address DHCP Refresh time 86400 seconds

 Number of sessions 1

  Session details:

   FSM in state Ready(7) on last event Rx Attach Ack(14)

   Username eap-md5-u@eap-md5.com

   Authentication method EAP

AAA session-id length 7, 0x30313233414243

   AAA termination-action 1

   Reauthentication attempts from subscriber 0, ASNGW 0

   Associated user group **any**

   Signalling address local 2.2.2.2, remote 10.1.1.82

   Signalling UDP port local 2231, remote 2231

   Idle for inbound 00:01:09, outbound 00:01:09

   Absolute timeout 1500, remaining 00:23:49

   Idle timeout 600 (both), remaining 00:08:50

   Ingress Address filtering 0 packets, 0 bytes

   Number of flows 1

    Flow details ISF(0)

     FSM in state SF Ready(4) on last event Up(1)

     Transaction ID used 0X8004(32772)

     Data ID local 0x8(8), remote 0x1(1)

     Data address local 2.2.2.2, remote 10.1.1.82

     Data traffic sent 2 packets, 705 bytes

     Data traffic received 2 packets, 1208 bytes

     Accounting last record sent Interim(3)

     Idle for inbound 00:01:09, outbound 00:01:09

     Service Flow information Downlink:

      Identifier 15

Security Key Exchange

After EAP authentication of the subscriber, the BWG computes the respective Access Keys (AKs) for each Base-Station. The BWG also caches the PMK for the duration of the authentication, and recomputes additional AKs when the SS/MSS moves to another BS.

Release 1.0 and above supports Re-Authentication triggered from the mobile, and generates a new PMK.

IP Address Allocation Using DHCP

Cisco BWG Release 1.0 and above supports external Dynamic Host Configuration Protocol (DHCP) server-based address allocation.

Note The only mechanism to assign addresses to the SS/MSS is based on DHCP.

The SS/MSS can use DHCP to allocate IP addresses. For Release 1.0 and above there is no MIP or PMIP, because the BWG is only targeting fixed and portable. The DHCP relay is resident in the BWG, and interacts with a DHCP server, provided when the user-groups are on different VRF.

Overlapping of addresses with usergroup is allowed only with VRF.

After successful authentication and setup of the Initial Service Flow, the MS triggers DHCP to acquire an IP address. The DHCP server is configured on the BWG per user-domain group. The DHCP messages are transported transparently over the R6 data path between the BS and the BWG. The addresses can be allocated by the corresponding DHCP server pertaining to the user-domain group. Overlapping addresses across different user-groups are supported. using loop back might be the ideal way, however if the "dhcp gateway address" is not configured the IP of Virtual Template will be used as the gi-address

The initial service flow does not permit any data traffic except DHCP packets. After address allocation is successfully completed, the appropriate classifiers are installed that correspond to the IP address assigned to the SS/MSS.

In order to support multiple hosts behind a Subscriber Station, multiple DHCP requests from subscriber stations will be supported. These requests can be received on the same or alternate service flows.

Configuring IP Address Allocation

To configure IP address allocation using an external-based DHCP server, perform the following task:


	Command	Purpose
Step 1	router# interface Loopback102 ip address 102.0.0.1 255.255.255.0 ! user-group domain eaptls.com2 aaa accounting method-list AAA-ACC1 aaa authentication method-list AAA-AUTHN1 dhcp gateway address 102.0.0.1 dhcp server primary 27.0.0.8 sla profile-name silver vrf VRF_2	Configures an external DHCP server to allocate IP addresses. The default ip address allocation time is 300 seconds.

Here is a sample configuration:

interface Loopback102

  ip address 102.0.0.1 255.255.255.0

 user-group domain eaptls.com2

  aaa accounting method-list AAA-ACC1

  aaa authentication method-list AAA-AUTHN1

  dhcp gateway address 102.0.0.1

  dhcp server primary 27.0.0.8

  service-flow pre-defined isf profile sf3

  service-flow pre-defined secondary 1 profile sf4

  vrf VRF_2

The DHCP server and gateway also can be configured under User Group. If you do not configure DHCP server or gateway address under the user group, the global configuration method is used.

Multiple Host Support

Multiple hosts behind an SS can be supported for IPCS, using DHCP Relay option 82, or option 82 - subscriber ID.

Subscriber-id sub-option of Option 82 could be set to the MSID of the MS/SS and the Circuit-id sub-option can be set to the downlink service flow identifier. A remote ID can be set to the SS/MSS's username for an authenticated user, and the VPNID can be set to the user's VRF name if configured. This includes the new sub option 200 for the L2 header

For example, the DHCP server can allocate a unique IP address for each MAC, to support a multi-host scenario.

Now, the subscriber ID will have the username, and the remote ID will have the MACID of the user.

Note For Release1.0 and above, relay cascading is not supported.

Note The maximum number of hosts allowed behind an MS is 8.

Support of Multiple Hosts Behind a SS

Multiple hosts are also supported over a single SS/MSS

Step 1 CPE (SS) undergoes initial network entry and authentication, and a bearer path is created.

Step 2 A basic R6 bearer path between the BS and the BWG is created. The basic R6 shares a GRE key for uplink/downlink, which may be mapped to the SFID and the corresponding airlink connection.

Step 3 All uplink and downlink packets are sent and received by the CPE for all the hosts on the same service flows (R6 bearer) at the BWG.

DHCP Option 82

DHCP option 82 is applicable for subscribers as well as host. This option is sent in any DHCP messages for any host or subscriber.

Multiple hosts can also be supported using the DHCP option 82. The Relay Agent Information option is inserted by the DHCP relay agent when it forwards client-originated DHCP packets to a DHCP server. Servers that recognize the Relay Agent Information option can use the information to implement IP address, or other parameter assignment policies. Additionally, the L2 header in case of Ethernet CS is also being inserted in option 82

DHCP options 82 appends subscriber id + remote id + circuit id. This is then sent in all DHCP messages toward the server. In case of VRF, VPN ID is also sent. If the DHCP server is not Option 82 aware, and does not echo back the option 82, the BWG drops the messages from DHCP server.

This feature is valuable because it allows you to do the following:

•Identify each subscriber

•Perform subscriber management

•Assign IP addresses based on subscriber info

•Set access control, QoS and security policies

Here is the sequence of events that occur for the DHCP Option 82 feature:

Step 1 Hosts set the client identifier field to the MAC address in the DHCP message.

Step 2 DHCP message communication is done only over ISF for procuring the CPE's IP address, and can be done on any of the flows for procuring the host's IP address. The DHCP packets from BWG are sent out on the same flow as the incoming DHCP message from the host.

Step 3 The BWG inserts the option 82 fields for use by the DHCP server. Option 82 shall be inserted into all DHCP messages towards the DHCP server. For the list of options to insert refer to Table 2-3

Step 4 The DHCP Server could allocate IP address using any of the options in the Option 82 field of the incoming DHCP packet. Once the IP address is allocated, the BWG learns the assigned IP address by monitoring the responses and maps it to the R6 bearer. This process is repeated for each host, and the address is tracked and mapped to the same R6 bearer.

Step 5 The BWG will monitor all DHCP messages, and ensure that the option 82 fields are inserted.

Table 2-3 DHCP Server Options
Sub-Option	Code	Length	Sub Value
Circuit ID	1	Variable	Downlink Service Flow ID
Subscriber ID	6	Variable	MSID (MAC-address of SS/MSS)
Remote ID	2	6	User name of the SS/MSS, for an authenticated user
Vendor-Specific Relay Information (Ethernet Header)	200		Ethernet CS L2 header
VPN-ID	151	Variable	VRF name, if the user belongs to a VRF.

Table 2-3 lists the DHCP Server Options.

DHCP Option 82 Enhancement in Release 1.1

Service Flow Creation and Management

802.16 supports multiple service flows for a given SS. The service flows are identified by mapping a set of classification rules over the packet bearer. Each service flow is a unidirectional flow and can have a different quality of service treatment, both on the airlink and on the network.

In Cisco BWG Release 1.0 and above, service flow creation is supported only when initiated by the network. This service flow creation will provision the classifiers on the SS/MSS as well.

Additionally, pre-provisioned service flow templates are configured on the BWG locally. AAA support for downloading the Service Flow Profile ID is not supported on the BWG.

Service Flows

The BWG manages the service flows for each SS/MSS. Release 1.0 and above only supports network triggered service flows. The BWG allocates SFID for each service flow, and triggers service flow creation. Each service flow also has its respective datapath (for example, GRE key, and the packets corresponding to each service flow are transported accordingly).

All pre-provisioned flows are assumed to be available for the lifetime of the SS/MSS session, and are not deleted.

Multiple Service Flow Creation

When the control plane comes up, the BWG requests the creation of the Initial Service flow with the base station. DHCP IP address allocation and flow creation go in parallel in BWG Release 1.1.

The flows are created one after the other in parallel to DHCP allocation occuring on the ISF. Launching the creation of a service flow happens only after the successful creation of the preceding one. A service flow "fails" to be created if it fails after "x retries" of registration request for this SF. If a SF "fails" to be created, it is bypassed (in case it is a secondary SF), or the session is torn down (if it is the inital SF).

For Release 1.0 and above, the BWG supports creating 4 service flows; the initial service flow, and 3 secondary service flow.

If a secondary SF creation fails, then the next flow is attempted and session continues without the failed SF.

Configuring BWG Service

To enable BWG services, use the following commands beginning in global configuration mode:


	Command	Purpose
Step 1	router(config)# service wimax agw	Enables WiMAX BWG services.
Step 2	router(config-if)# encapsulation agw	Clones a Virtual-Access interface of encapsulation type "ASNGW". Configure this command in Virtual-Template configuration mode.

Sample Configuration

Here is a sample configuration to clone the Virtual Address:

interface Virtual-Template1

ipaddress 2.2.2.2 255.255.0.0

encapsulation agw

ip mtu 1440

no keepalive !

The Gi address is picked from the Virtual Address by default. You can use the user-group configuration to override the Gi address.

Verifying the Configuration

To verify that BWG services are enabled, and to display MS State Change and Data Path statistics, use the show wimax agw statistics command in privileged EXEC mode:

Message type Deregistration Request(4/0x4)

   Number of messages sent 1

   Number of messages received 11

   Number of messages resent 0

  Message type Deregistration Response(5/0x5)

   Number of messages sent 6

   Number of messages received 1

   Number of messages resent 10

  Message type Deregistration Ack(6/0x6)

   Number of messages sent 1

   Number of messages received 5

   Number of messages resent 0

  Message type Registration Request(12/0xC)

   Number of messages sent 6

   Number of messages received 0

   Number of messages resent 0

  Message type Registration Response(13/0xD)

   Number of messages sent 0

   Number of messages received 6

   Number of messages resent 0

  Message type Registration Ack(14/0xE)

   Number of messages sent 6

   Number of messages received 0

   Number of messages resent 0

Message function type Context Delivery(4/0x4)

  Message type Context Delivery Request(1/0x1)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Context Delivery Report(2/0x2)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Message function type Auth Relay(8/0x8)

  Message type EAP Start(1/0x1)

   Number of messages sent 0

   Number of messages received 2

   Number of messages resent 0

  Message type EAP Transfer(2/0x2)

   Number of messages sent 56

   Number of messages received 56

   Number of messages resent 0

  Message type Key Change Directive(5/0x5)

   Number of messages sent 8

   Number of messages received 0

   Number of messages resent 0

  Message type Key Change Confirm(6/0x6)

   Number of messages sent 0

   Number of messages received 2

   Number of messages resent 0

Message type Key Change ACK(7/0x7)

   Number of messages sent 2

   Number of messages received 8

   Number of messages resent 0

  Message type CMAC Key Count Update(8/0x8)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type CMAC Key Count Update Ack(9/0x9)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Message function type MS State Change(9/0x9)

  Message type Attachment Response(7/0x7)

   Number of messages sent 6

   Number of messages received 0

   Number of messages resent 0

  Message type Attachment Request(8/0x8)

   Number of messages sent 0

   Number of messages received 6

   Number of messages resent 0

  Message type Attachment ACK(9/0x9)

   Number of messages sent 0

   Number of messages received 6

   Number of messages resent 0

  Message type Pre Attachment Request(15/0xF)

   Number of messages sent 0

   Number of messages received 6

   Number of messages resent 0

  Message type Pre Attachment Response(16/0x10)

   Number of messages sent 6

   Number of messages received 0

   Number of messages resent 0

  Message type Pre Attachment ACK(17/0x11)

   Number of messages sent 0

   Number of messages received 6

   Number of messages resent 0

Message function type Keepalive(20/0x14)

  Message type Keepalive Request(1/0x1)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Keepalive Response(2/0x2)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Handoff Statistics

  Message type Successful Handoff

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Registration Request

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Registration Response

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Registration Ack

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Message type Handoff Deregistration Request

  Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Deregistration Response

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Deregistration Ack

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Undefined Message Function / Message Type

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Mapping of Service Flows to DiffServ Classes

The BWG maps each individual Service flow to a Diffserv Class. The mapping rules are configured on the router. The mapping rules are designated in Table 2-4:

Table 2-4 Map of Each Individual Service Flow to a Diffserv Class
Service Flow - QoS Class	Applications	Diffserv Class on Network
UGS (Unsolicited Grant Service)	Voice/Video	EF
Real Time Polling Service	Voice/Video	EF
Non-Real Time Polling Service	Interactive Services	AF
Best Effort	Web Traffic	BE

Marking of Packets Corresponding to Service Flows

Each packet is identified and grouped according to the associated service flow. The transport headers corresponding to the packets are then marked with the associated Diffserv Code Point (DSCP) by the BWG based on the above table.

Configuring Service Flows on the BWG

To create service flows on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)# wimax agw service-flow profile service-flow-profile-name	Specifies a service-flow profile on the BWG. The no version of the command removes the profile. service-flow-profile-name is case insensitive. Configuring this command enters service flow configuration mode.
Step 2	router(config-gw-sf)# direction {uplink \| downlink}	Specifies the direction of the service-flow the configuration is done, and enters service flow direction configuration submode. The no version of the command removes the corresponding configuration from the direction specified. The default value is best effort.
Step 3	router(config-gw-sf)# cs-type {ethernet-cs \| ip-cs}	Specifies the cs-type profile under the corresponding direction. The no version of the command removes the cs-type information from the corresponding direction. Configuring the command opens a sub configuration mode to configure various cs-type commands.
Step 4	router(config-gw-sf-dir-cstype)# precedence 1-2	Specifies the precedence of the cs-type under the direction which it is configured. The precedence gets used as a tie-breaker when an MS can support more than one cs-type. The no version of the command removes the precedence information from the corresponding cs-type.
Step 5	router(config-gw-sf-dir-cstype# vlan {2-4095 \| range 2-4095 2-4095} vrf vrf-name	Specifies the vlan to vrf mapping (frames with a particular vlan-id will be mapped to what vrf-name). There is also a provision of specifying the range of vlan-ids mapped to a vrf-name. Note This vlan-vrf mapping can be configured for ethernet-cs for direction uplink only.
Step 6	vrf default vrf-name	Optional configuration command that specifies the default vrf mapping. Uplink frames without a vlan-id, or with a vlan-id that is not configured under this cs-type with a vlan-vrf mapping will be mapped to the vrf-name configured using this command. Note The vrf-default can be configured for ethernet-cs and ip-cs for direction uplink only.
Step 7	router(config-gw-sf-dir)# qos-info qos-profile-name	Specifies which QoS information profile is associated under the corresponding direction. The no version of the command removes the QoS information from the corresponding direction.
Step 8	router(config-gw-sf-dir)# set {dscp \| precedence} {precedence-value \| dscp-value}	Specifies what DSCP or TOS marking needs to apply for the subscriber packets in the downstream direction. By default no marking is done.
Step 9	router(config-gw-sf-dir-cstype)# pak-classify-rule	Specifies which packet classification rule profile is associated under the corresponding direction. The no version of the command removes the packet classification rule from the corresponding direction.

Configuration Example

The following are examples of Service Flow configuration commands:

wimax agw service-flow profile isf

 direction downlink

  cs-type ip-cs

   pak-classify-rule isf-classifier-downlink

   precedence 1

  cs-type ethernet-cs

   pak-classify-rule isf-classifier-downlink

   precedence 2

  qos-info isf-qos-downlink

 direction uplink

  cs-type ip-cs

   pak-classify-rule isf-classifier-uplink

   precedence 1

  cs-type ethernet-cs

   pak-classify-rule isf-classifier-uplink

   precedence 2

   vlan 2 vrf vrf_1

   vlan range 3 10 vrf vrf_2

   vrf-default vrf_1

  qos-info isf-qos-uplink

wimax agw service-flow profile 2sf

 direction downlink

  cs-type ip-cs

   pak-classify-rule dn-secondary-01

   qos-info downlink-qos-02

   set dscp ef

   set precedence immediate

 direction uplink

  cs-type ip-cs

   pak-classify-rule up-secondary-01

   qos-info uplink-qos-02

Configuring Service Flow Packet Classification

To configure a service-flow packet classification rule profile on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)# wimax agw service-flow pak-classify-rule profile profile-name	Specifies a service-flow packet classification rule profile on the BWG. These are configured under the predefined service flows that are to be opened for the subscriber. When configured, this command enters into the packet classify rule configuration submode.
Step 2	router(config-gw-pak-classify-rule-pr)# priority 0-255 IPv4 classifiers===> ip permit {0-255 \| gre \| tcp \| icmp \| udp \| ip} {src-address src-mask \| any \| host src-address} [range src-port-low [src-port-high] {dst-address dst-mask \| any \| host dst-address} [range dst-port-low [dst-port-high] [tos tos-low tos-mask tos-high] Ethernet related classifiers ===> ethernet permit {src_mac src_mac_mask \| any} {dst_mac dst_mac_mask \| any} {0-FFFF \| any \| arp \| ipv4}] VLAN related classifiers ===> vlan permit {2-4095 \| any } priority {0-7 \| any \| range #start #end}	Sets the packet classification rule under the profile. Each packet classification rule should have a unique priority associated with it. BWG currently supports IPv4, Ethernet and VLAN related rules.

Configuration Example

Here is a sample configuration of the Service Flow Packet Classification configuration commands:

wimax agw service-flow pak-classify-rule profile sec1-classifier-uplink

 priority 0

  ipv4 permit ip any any

  ethernet permit any any any

  vlan any priority any

 priority 1

  vlan 300 priority 4 7

 priority 2

  ethernet permit 0032.00AE.0023 ffff.ffff.ffff any arp

 priority 3

  ipv4 permit ip 2.2.2.2 /24 192.168.102.0 /24 tos 0 255 100

 priority 4

  ethernet permit any 0032.00AE.0023 ffff.ffff.ffff 8100

  vlan permit 900 priority 4

 priority 5

  ipv4 permit ip 2.2.2.2 /24 192.168.102.0 /24 tos 0 255 100

  ethernet permit 001C.B046.041B ffff.ffff.0000 0032.00AE.0023 ffff.0000.0000 ipv4

  vlan permit 300 priority range 4 7

Note The packet classifiers are viewed collectively for a given user and direction of flow for each packet, and the highest matching priority rule is applied (255 is highest priority). If no classifiers match, the default flow chosen is the ISF in the downlink direction.

QoS Support

QoS support refers to both airlink QoS as well as mapping on the network. The BWG is responsible for sending the QoS parameters to the BS used to create the appropriate service flows.

Certain hosts can be given additional QoS parameters.

A new R6 bearer (service flow) is created that corresponds to the host's IP address. Multiple hosts can use this service flow.

Mapping of the host to the new R6 service flow is created and communicated to the BS/MS through the RR-Request.

BWG Release 1.0 and above offers the following support:

•Support for pre-provisioned QoS through CLI.

•Support for signaling traffic to be marked as separate class.

•Corresponding to every service flow based on the classifiers, a Diffserv Class would be mapped and used by the BS and the BWG.

•Support for all QoS class of service.

Configuring QoS

To configure QoS on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)# wimax agw service-flow profile qos-info service-flow-qos-info-profile-name	Allows the user to configure a service-flow QoS information profile on the BWG. These are associated to predefined service flows that are opened for the subscriber. Configuring the command opens a sub-configuration mode to configure various parameters.
Step 2	router(config-gw-sf-qos-info)# data-delivery-service {unsolicited-grant\|real-time-variable-rate\|non-real- time-variable-rate\|best-effort\| extended-real-time-variable-rate}	Configures data delivery service associated with certain predefined set of QoS-related service flow parameters. The default value is unsolicited-grant.
Step 3	router(config-gw-sf-qos-info)# maximum-latency maximum-latency-value	Configures the time period between the reception of a packet by the BS or MS on its network interface, and delivery of the packet to the RF interface of the peer device. If defined, this parameter represents a service commitment (or admission criteria) at the BS or MS, and is guaranteed by the BS or MS. A BS or MS does not have to meet this service commitment for service flows that exceed their minimum reserved rate. The default value is 0.
Step 4	router(config-gw-sf-qos-info)# maximum-traffic-burst maximum-traffic-burst-value	Configures the parameter that defines the maximum burst size that is accommodated for the service. Since the physical speed of the ingress and egress ports, the air interface, and the backhaul are greater than the maximum sustained traffic rate parameter for a service, this parameter describes the maximum continuous burst the system should accommodate for the service if the service is not currently using any of its available resources. The default value is 0.
Step 5	router(config-gw-sf-qos-info)# maximum-traffic- rate-sustained maximum-traffic-rate-sustained-value	Configures the parameter that defines the peak information rate of the service.
Step 6	router(config-gw-sf-qos-info)# media-flow-type media-flow-type-hex-string	Specifies the parameter that describes the application type, used as a hint in admission decisions; for example, VoIP, video, PTT, gaming, or others.
Step 7	router(config-gw-sf-qos-info)# policy-transmission-request policy- transmission-request-value	Specifies the policy transmission request value for the associated service flow. This value includes options for PDU formation, for uplink service flows, and restrictions on the types of bandwidth request options that may be used. An attribute is enabled by setting the corresponding bit position to 1.
Step 8	router(config-gw-sf-qos-info)# minimum-traffic- rate-reserved minimum-traffic-rate-reserved-value	Specifies (in bits per second) the minimum amount of data to be transported on behalf of the service flow when averaged over time. The specified rate is only honored when sufficient data is available for scheduling. When sufficient data does not exist, the available data is transmitted as soon as possible.
Step 9	router(config-gw-sf-qos-info)# sdu-size sdu-size-value	Specifies number of bytes in the fixed size SDU. This parameter is used for a UGS service flow when the length of IP packets on the data plane is fixed and known in advance. This is typically the case for flows generated by a specific codec. The default value is 49.
Step 10	router(config-gw-sf-qos-info)# tolerated-jitter tolerated-jitter-value>	Specifies the maximum delay variation (jitter) for the connection.
Step 11	router(config-gw-sf-qos-info)# traffic-priority traffic-priority-value	Specifies the priority assigned to a service flow. For service flows that are identical (except priority), give the higher priority service flow a lower delay and higher buffering preference. For dissimilar service flows, the priority parameter does not take precedence over any conflicting service flow QoS parameter. The specific algorithm to enforce this parameter is not mandated here.
Step 12	router(config-gw-sf-qos-info)# unsolicited-interval-grant unsolicited-interval- grant-value	Specifies the nominal interval between successive data grant opportunities for this service flow. This parameter is used for a UGS and ERT-VR service flow when the inter-arrival time of IP packets on the data plane is known in advance (this is typically the case for flows generated by a specific codec).
Step 13	router(config-gw-sf-qos-info)# unsolicited- interval-polling unsolicited-interval-polling-value	Specifies the maximum nominal interval between successive polling grant opportunities for this service flow.

Configuration Example

Here is a QoS configuration example:

wimax agw service-flow qos-info profile isf-qos-downlink

 data-delivery-service real-time-variable-rate

 maximum-latency 1

 maximum-traffic-burst 2

 maximum-traffic-rate-sustained 3

 media-flow-type 012041424344

 minimum-traffic-rate-reserved 4

 policy-transmission-request 5

 sdu-size 6

 tolerated-jitter 7

 traffic-priority 1

 unsolicited-interval-grant 8

 unsolicited-interval-polling 9

wimax agw service-flow qos-info profile isf-qos-uplink

 data-delivery-service unsolicited-grant

 maximum-latency 11

 maximum-traffic-burst 21

 maximum-traffic-rate-sustained 31

 minimum-traffic-rate-reserved 41

 policy-transmission-request 51

 sdu-size 61

 tolerated-jitter 71

 traffic-priority 3

 unsolicited-interval-grant 81

 unsolicited-interval-polling 91

wimax agw service-flow qos-info profile downlink-qos-02

 data-delivery-service real-time-variable-rate

 media-flow-type 05abcd

Verifying the Configuration

To verify the QoS values on the BWG, use the show wimax agw subscriber command. Here is sample output for QoS statistics:

Router>sh wimax agw subscriber

MSID 1000.2228.0001

  Connection time 000:00:14

  Auth policy 0X0(0)

  Number of TIDs 1

  TID Key 10.1.1.70/2.2.2.2/1000.2228.0001

   Peer TID 0X2(2)

     FT MS State Change(9), MT Attachment Request(8)

   Our TID 0x8001(32769)

QoS information:

      Data-delivery-service real-time-variable-rate

      Minimum traffic-rate-reserved 4, Maximum latency 1

      Unsolicited interval-polling 9, Traffic-priority 1

      Maximum traffic-rate-sustained 3, Request/Transmission-

       policy 5

      Maximum traffic-burst-rate 2

      Reduced-resources-code 0

     Classifier information:

      priority 0 permit ip host 0.0.0.0 host 0.0.0.0

Service Flow information Uplink:

      Identifier 4

     QoS information:

      Data-delivery-service unsolicited-grant

      Minimum traffic-rate-reserved 41, Maximum latency 11

      Tolerated-jitter 71, SDU-size 61

      Unsolicited interval-grant 81, Request/Transmission-policy 51

      Reduced-resources-code 0

     Classifier information:

      priority 0 permit ip host 0.0.0.0 host 0.0.0.0

Table 2-5 and Table 2-6 identify the QoS Classes and Service Parameters for 802.16.

Table 2-5 QoS Classes in 802.16
QoS Parameter	BE Best Effort Service Flow	ERT-VR	UGS	RT-VR	NRT-VR
Traffic Priority 0-7 Def: 0	Optional	Optional [a]		Optional [a]	Optional [a]
Maximum sustained rate 0-4294967295 bits per second	Optional	Optional [b]		Optional [b]	Optional [b]
Minimum reserved rate 0-4294967295 bits per second		X	X	X	X
Maximum Traffic burst 0-4294967295 bits per second		Optional		Optional	Optional
Jitter Tolerance 0-4294967295 msc		Optional [c]	Optional [c]
Maximum latency Tolerance 0-4294967295 msc		X	X	X
Unsolicited Grant Interval 0-65535 msc		X	X
SDU Size 0-255 Bytes Def: 49			Optional [d]
Unsolicited Polling Interval 0-65535 msc				X
DSCP

Table 2-6 QoS Classes and Service Parameters in 802.16
QoS Class	Application	QoS Spec Service Parameter
Unsolicited grant service (UGS)	VoIP For real-time, fixed size regularly transmitted packets, e.g., voice codec, ATM CBR, E1/T1 over ATM.	Maximum sustained rate Maximum latency tolerance Jitter tolerance
Real-time polling service (rtPS)	Streaming Audio, Video For real-time variable size regularly transmitted packets, e.g., MPEG video, VoIP, streaming.	Minimum reserved rate Maximum sustained rate Maximum latency tolerance Traffic priority
Extended Real-Time Packet Service (ErtPS)	VoIP (with VAD)	Minimum reserved rate Maximum sustained rate Maximum latency tolerance Jitter tolerance`
Non-real-time polling service (nrtPS)	FTP For non-real-time service flows, requiring variable size, regular Data Grant Burst, e.g., Internet access, ATM GFR	Minimum reserved rate Maximum sustained rate Traffic priority
Best effort service flow (BE)	Data Transfer, Web, Browsing	Maximum sustained rate Traffic Priority

User Group Management

To configure user groups on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)#wimax agw user group-list user-group-list-name	Configures the user group list on the BWG router. The no version of command removes the user group list. Enabling this command enters you into user group list sub configuration mode to create multiple user groups under the user-group list created.
Step 2	router(config-gw-ug)# service-flow pre-defined {isf \| secondary secondary-index} profile sf-profile-name	Specifies the number of pre-defined service flows to be opened for a subscriber. If the ISF keyword is configured, the service flow is assumed to be the initial service flow. The secondary keyword represents the auxiliary service flows for the subscriber. Currently 1 initial service flow, and up to 3 secondary service flows, are allowed per subscriber.
Step 3	router(config-gw-ug)#ip static-allowed	Allows the creation of static hosts for sessions that are part of this user-group. By default static hosts will not be allowed.

Sample Configuration

The following example illustrates how to configure a user group:

wimax agw user group-list wimax

 user-group any

  aaa accounting method-list agw

  sla profile-name gold

  dhcp server primary 12.1.1.2

user-group domain cisco.com

  aaa accounting method-list agw

  sla profile-name gold

  ip static-allowed

  ip route aggregate auto

user-group unauthenticated

  aaa accounting method-list agw

  aaa authentication method-list agw

  sla profile-name gold

  ip static-allowed

  user auto-provisioning

  proxy realm cisco.com password ciscoway

Idle Timer Support

An idle timer is configurable on the BWG for a User group. If there is no data traffic for the duration of the timer, the SS/MSS will be de-registered. Idle timeout can be downloaded from the AAA server during the authentication phase.

Here is a sample configuration:

wimax agw user group-list wimax

 user-group any

  aaa accounting method-list agw

  dhcp server primary 11.1.1.93

  service-flow pre-defined isf profile isf

  timeout idle 30

  timeout session 30

 user-group unauthenticated

  aaa accounting method-list agw

  dhcp server primary 11.1.1.93

  service-flow pre-defined isf profile isf

  service-flow pre-defined secondary 1 profile 2sf

Idle timer support is available for inbound traffic in the ASN.

If an idle timer value is configured in AAA and under an ASN user-group, then AAA is given precedence.

Session Timer Support

A Session or Absolute timer is configurable on the BWG for a User group. When the timer expires, the subscriber is de-registered. Session timeout can be downloaded from the AAA server during the authentication phase.

Mobile Subscriber Station De-Registration

Cisco BWG Release 1.0 and above supports Network Exit as a result of Path Deregistration messaging.

There are two possible ways to deregister a Mobile Subscriber Station:

Mobile Subscriber Station Initiated De-Registration

Step 1 The SS sends DREG-REQ message to the BS, to start de-registration procedure.

Step 2 The BS sends Data Path De-Reg Request to BWG.

Step 3 BWG sends Data Path De-Reg Response to BS with the action code (set to 0x04) to authorize de-registration procedure.

Step 4 BS sends DREG-CMD to SS to de-register the SS.

Step 5 BS sends Data Path De-Reg Ack to BWG to complete the transaction.

Network-Initiated De-Registration

Step 1 The BWG sends out a Data Path De-Reg Request message to the BS indicating the MS to be deleted.

Step 2 The BS sends out a DSD-REQ over the airlink to deregister the specific Service Flows.

Step 3 BS gets DSD-RSP from SS indicating the termination of the service flow.

Step 4 BS sends Data Path De-Reg Response to BWG indicating the termination of service flow.

Step 5 BWG sends Data Path De-Reg Acknowledgement, to terminate the transaction.

AAA Accounting Start-Stop-Interim

The BWG supports both per service flow accounting information, and host based accounting information. Only time based interim accounting updates are supported. The BWG supports per service flow, and generates a unique set of accounting records for each service-flow tuple (Acct-Session-Id + Acct-Multi-Session-Id + PDFID). Each service flow is uniquely identified by a GRE key. A given MS can have more than one service flow.

Note Per-session accounting is not supported in this release.

For all the accounting records sent by the BWG, the Framed-IP-Address field is set to the mobile's IP address, irrespective of which host behind the mobile the traffic is sent for.

The BWG sends the following messages to the AAA server:

•Accounting Start: The BWG sends this message to the AAA server when a new service flow is created. In case of redundant BWG configuration, a stand-by BWG sends an Accounting Start message only when it becomes active. The trigger for the Accounting Start is the successful creation of the service flows. In case of the initial service flow, the accounting start record is sent only after the IP address is allocated to the users. For the secondary service flow, the accounting record is sent as soon the flow is successfully opened with the BS.

•Accounting Interim Update: The BWG generates an Accounting Update message if periodic accounting update message is configured. The accounting updates are based on a time trigger, and when configured. The minimum permitted value for the timer is 1 minute.

•Accounting Stop: The BWG sends and Accounting Stop message when the service flow is deleted or when the MS completes the deletion.

The attributes sent in the accounting record are listed in Table 2-7:

Table 2-7 BWG-AAA Authentication Attributes
Attribute	Type	Description	Access Request	Access Challenge	Access Accept	Access Reject
User-Name	1	NAI obtained from the EAP-Response Identity (Outer-NAI)	1	0	0-1
Service-Type	6	Set to "Framed" for initial authentication and set to "Authenticate-Only" indicating Re-authentication. It may also be set to "Authorize-Only" when used to obtain prepaid quotas mid-session.	1	0	0-1	0
Framed-MTU	12	Used by WiMAX, as per RFC3579 in an Access-Request during EAP authentication, this attribute provides the appropriate MTU size to avoid exceeding maximum payload size for PKMv2 (2008 bytes) during EAP exchange (the appropriate fragmentation is assumed in Authentication Server on the EAP application layer). The value of this attribute should be set between 1020 and 2000 bytes (the recommended value is 1400 bytes). In an Access-Accept the use is as per RFC2865.	0-1[m]	0	0-1[m]	0
EAP-Message	79	The EAP message	1-n	1-n	1-n	1-n
Message-Authenticator	80	Provides integrity protection for the RADIUS packets as required by [RFC3579]	1	1	1	1
WiMAX-Capability	26/1	Identifies the WiMAX Capabilities supported by the NAS. Indicates capabilities selected by the RADIUS server.	1	0	0-1[k]	0
NAS-ID	32	FQDN of the NAS	1[b]	0	0	0
NAS-Port-Type	61	Identifies the type of port the request is associated with. Set to WiMAX when coming from a WiMAX ASN. Set to MIPv4 or MIPv6 when coming from an HA.	1	0	0	0
Calling-Station-Id	31	Set to the MAC address of the Device(MS).	1	0	0	0
Device-Authentication-Indicator	26/2	Indicates whether the device authentication was performed, and the result.	0-1[i]	0	0	0
GMT Timezone-Offset	26/3	The offset in seconds from GMT at the NAS.	1	0	0	0
NAS-IP-Address	4	NAS IP Address. Either NAS-IP-Address.	0-1[b]	0	0	0
Error-Cause	101	Error Codes generated during access authentication [RFC3576].	0	0-1	0	0-1
Class	25	Opaque value set by the server used to bind authentication to accounting.	0	0	0-1[h][k]	0
Framed-IP-Address	8	The MIPv4 home address to be assigned to the MN.	0	0	0-1[c][k]	0
Session-Timeout	27	The maximum number of seconds of service to be provided to the user before termination of the session. Associated with the lifetime of the keys	0	0	0-1[d][k]	0
Termination-Action	29	Indicates what action the NAS should take when service is completed.	0	0	0-1[d][k]	0
AAA-Session-ID	26/4	A unique identifier in the home realm for this Session.	0-1[e]	0-1	1	0
BS-ID	26/46	Indicates the NAP-ID and BS-ID at the time the message was delivered	0-1[n]	0	0	0
MSK	26/TBD	The Master Session Key derived as the result of successful EAP Authentication.	0	0	1[f]	0
Session-Timeout	27	The maximum number of seconds of service to be provided to the user before termination of the session. Associated with the lifetime of the keys derived from the EAP authentication (i.e., MSK, EMSK and keys derived from EMSK) Session-Timeout in an Access-Challenge packet is used set the EAP-retransmission timer as per RFC3579.	0	0-1	0-1[d][k]	0

[b] NAS-ID MUST appear in the Access-Request. NAS-IP-Address may also appear. NAS-ID may be configured on the CLI using the radius-server attribute 32 include-in-access-req command.

[c] If this attribute is present then the home address assigned to the mobile must be as specified by this attributes. If this attribute is absent then the home address is derived from MIP procedures or other means (for example, DHCP).

[d] Both Session-Timeout and Termination-Action MUST be present. Termination-Action MUST be set to "RADIUS-Request"(1). This causes the NAS to re-authenticate when the Session-Timeout expires.

[f] The attribute must be encrypted using the procedures in section 3.5 of RFC2868

[h] If more then one class attribute is found in an Access-Accept message, the NAS shall store all of them and send them back in the accounting request packets.

[i] Must appear in the Access-Request associated with the User Authentication phase of the Double EAP Device, user authentication procedure. Otherwise, the attribute MUST not be present in the Access-Request message.

[k] Attributes must not appear in the Access Accept sent associated with the Device Authentication phase of double EAP.

[m] If the Framed MTU appears in an Access-Request during Access-Authentication then it indicates the MTU on the link between the NAS and the MS. As per RFC3579, the RADIUS shall not send any subsequent packet in this EAP conversation containing EAP-Message attributes whose values, when concantenated, exceed the length specified by the Framed-MTU value.

[n] Either the BS-ID or NAP-ID SHALL be provided. If both are provided the receiver SHALL ignore the NAP-ID attribute. In Release 1.0 and above, NAP_ID is not sent to AAA. NAP-ID is 24 (MSB) bits of 48 bit BSID (when BS will send it in future).

Host Based Accounting

In BWG Release 1.2, the BSG also supports host-based accounting due to the fact that IP address allocation and de-allocation happens on a host level.

Both flow and host-based accounting can be enabled or disabled under the user group. And both host and flow modes can be enabled simultaneously. By default, flow accounting is enabled and host accounting is disabled.

If host accounting is enabled for a host in a user group, then the BWG initiates accounting by sending an Accounting Start request to the RADIUS server every time a host (default host is known as the CPE, DHCP host behind the CPE, Static Host) gets created on BWG. An accounting stop request is sent if the session gets de-registered or the host gets deleted.

The list of attributes that needs to be sent in Accounting Request differs for flow and host accounting. For example, the remote_id tag is included only for host accounting.

Here is a list of the attributes needed for host-based accounting:

•Framed-Protocol

•Called-Station-Id

•Remote Id = MACID of MODEM/CPE

•User-name

•Farmed-Ip-Address = IP address of Host/CPE

•Vrf-Id (if any)

•Calling-Station-Id = MACID of host

•Basesation-ID

Configuring AAA Accounting

To enable the accounting feature on the BWG, perform the following tasks:


	Command	Purpose
Step 1	router(config)# aaa accounting network {accounting-list-name} {none\|start-stop\|stop-only} {broadcast\|group} {server-group-name\|radius}	Enables the accounting for network services. For WiMAX, an accounting method list name is required.
Step 2	router(config)# aaa accounting update {newinfo\|periodic} {periodic intervals to send accounting updates in minutes}	Enables the accounting updates at periodic intervals. The no version of this command disables the sending of accounting updates.
Step 3	router(config)# wimax agw user group-list user-group-list-name	Configures the user group list on the BWG router. Only one user group list is allowed on a single processor of the BWG. The no version of command removes the user group list. This command enters a user group list sub-configuration mode to create multiple user groups under the user-group list created.
Step 4	router(config-gw-ug)#aaa accounting ? flow User group AAA accounting flow commands host User group AAA accounting host commands method-list User group AAA accounting method list configuration commands router(config-gw-ug)#aaa accounting host ? enable Enable User group AAA accounting per host	Enables flow based or host-based accounting. Both flow and host-based accounting can be enabled or disabled under the user group. And both host and flow modes can be enabled simultaneously. To see sla-profile and user-realm in flow accounting, configure radius-server vsa send accounting and radius-server vsa send accounting wimax on the BWG. Sla-profile and user-realm do not show up in host accounting.
Step 5	router(config-gw-ug)# aaa accounting method-list {method-list-name\| default}	Specifies the accounting method list used for the domain.

Configuration Example

Here is an example of a user group configuration:

wimax agw user group-list wimax

  user-group any

   aaa accounting method-list agw

   aaa authentication method-list agw

  user-group domain cisco.com

   aaa accounting method-list agw

   aaa authentication method-list agw

  user-group unauthenticated

   aaa accounting method-list agw

Here is an example of a AAA and RADIS configuration:

aaa new-model

aaa accounting update periodic 15

aaa accounting network agw start-stop group radius

aaa authorization network default group radius

aaa authentication dot1x agw group radius

radius-server attribute 32 include-in-access-req format %h.%d.%i

radius-server attribute 55 access-request include

radius-server attribute 25 accounting prefer-preauth

radius-server vsa send accounting wimax

radius-server vsa send authentication wimax

radius-server host 172.19.25.8 auth-port 1645 acct-port 1646 key cisco

radius-server host 1.8.91.8 auth-port 1645 acct-port 1646 key cisco

You can disable flow accounting by configuring no aaa accounting flow enable. As a result, no aaa accounting flow enable will appear under user-group profile.

Here is a sample configuration when flow accounting is disabled

user-group domain cisco.com

  aaa accounting method-list agw

  no aaa accounting flow enable

  sla profile-name platinum

  timeout idle 3000

  timeout session 86400

You can enable flow accounting by configuring the aaa accounting flow enable command. Here is a sample configuration when flow accounting is enabled

user-group domain cisco.com

  aaa accounting method-list agw

  sla profile-name platinum

  timeout idle 3000

  timeout session 86400

Here is a sample configuration for host-based accounting:

 user-group domain cisco2.com

  aaa accounting method-list agw

  sla profile-name gold

  ip static-allowed

  security subscriber address-filtering ingress

  subscriber network-behind

  aaa accounting host enable

Verifying the Configuration

Here is an example of the show wimax agw subscriber command, used to verify the accounting configuration:

Router#sh wimax agw subscriber msid 1000.0002.0001

 Connection time 000:01:08

 Auth policy 0X12(18), Single-EAP, CMAC

 Number of TIDs 1

 TID Key 10.1.1.82/2.2.2.2/1000.0002.0001

  Peer TID 0X4(4)

    FT MS State Change(9), MT Attachment Request(8)

  Our TID 0x8004(32772)

 Subscriber address 2.2.0.8, type IPv4, organization IETF

 Subscriber address method Dynamic, source DHCP relay

 Subscriber address assigned on flow downlink ID 15

 Subscriber address prefix len allocated 32, aggregate 32

 Subscriber address traffic sent 0 packets, 0 bytes

 Subscriber address traffic received 0 packets, 0 bytes

 Subscriber address DHCP XID 2390, server 0.0.0.0, htype 1

 Subscriber address DHCP client ID 1000.0002.0001, length 6

 Subscriber address DHCP Refresh time 86400 seconds

 Number of sessions 1

  Session details:

   FSM in state Ready(7) on last event Rx Attach Ack(14)

   Username eap-md5-u@eap-md5.com

   Authentication method EAP

AAA session-id length 7, 0x30313233414243

   AAA termination-action 1

   Reauthentication attempts from subscriber 0, ASNGW 0

   Associated user group **any**

   Signalling address local 2.2.2.2, remote 10.1.1.82

   Signalling UDP port local 2231, remote 2231

   Idle for inbound 00:01:09, outbound 00:01:09

   Absolute timeout 1500, remaining 00:23:49

   Idle timeout 600 (both), remaining 00:08:50

   Ingress Address filtering 0 packets, 0 bytes

   Number of flows 1

    Flow details ISF(0)

     FSM in state SF Ready(4) on last event Up(1)

     Transaction ID used 0X8004(32772)

     Data ID local 0x8(8), remote 0x1(1)

     Data address local 2.2.2.2, remote 10.1.1.82

     Data traffic sent 2 packets, 705 bytes

     Data traffic received 2 packets, 1208 bytes

     Accounting last record sent Interim(3)

     Idle for inbound 00:01:09, outbound 00:01:09

     Service Flow information Downlink: Identifier 15

Here is sample RADIUS output for a AAA accounting start:

*Aug 11 02:27:21.143: RADIUS(00000006): Send Accounting-Request to

 1.8.91.8:1646 id 1646/61, len 165

*Aug 11 02:27:21.143: RADIUS:  authenticator C4 F4 3F A3 00 1C 01 66 - 78

 DD A4 B4 68 37 F9 5B

*Aug 11 02:27:21.143: RADIUS:  Acct-Session-Id     [44]  10  "00000006"

*Aug 11 02:27:21.143: RADIUS:  Framed-Protocol     [7]   6   noval0

[0]

*Aug 11 02:27:21.143: RADIUS:  Called-Station-Id   [30]  9   "2.2.2.2"

*Aug 11 02:27:21.143: RADIUS:  Framed-IP-Address   [8]   6   2.2.0.76                  
*Aug 11 02:27:21.143: RADIUS:  Calling-Station-Id  [31]  19  "10-00-22-

 25-00-01"*Aug 11 02:27:21.143: RADIUS:  Acct-Input-Octets   [42]  6   1208                      
*Aug 11 02:27:21.143: RADIUS:  Acct-Output-Octets  [43]  6   666                       
*Aug 11 02:27:21.143: RADIUS:  Acct-Input-Packets  [47]  6   2                         
*Aug 11 02:27:21.143: RADIUS:  Acct-Output-Packets [48]  6   2                         
*Aug 11 02:27:21.143: RADIUS:  Vendor, Wimax       [26]  13

*Aug 11 02:27:21.143: RADIUS:   GMT-Time-Zone-Offse[3]   7

*Aug 11 02:27:21.143: RADIUS:   00 00 00 00 00

 [?????]

*Aug 11 02:27:21.143: RADIUS:  Vendor, Wimax       [26]  11

*Aug 11 02:27:21.143: RADIUS:   Packet-Data-Flow-ID[26]  5

*Aug 11 02:27:21.143: RADIUS:   00 00 00

 [???]

*Aug 11 02:27:21.143: RADIUS:  Acct-Session-Time   [46]  6   1630                      
*Aug 11 02:27:21.143: RADIUS:  Acct-Status-Type    [40]  6   start

[3]

*Aug 11 02:27:21.143: RADIUS:  NAS-Port-Type       [61]  6   802.16e Wimax

 [27]

*Aug 11 02:27:21.143: RADIUS:  NAS-Port-Id         [87]  11  "WiMAX-AGW"

*Aug 11 02:27:21.143: RADIUS:  Service-Type        [6]   6   Framed

[2]

*Aug 11 02:27:21.143: RADIUS:  NAS-IP-Address      [4]   6   2.2.2.2                   
*Aug 11 02:27:21.143: RADIUS:  Acct-Delay-Time     [41]  6   0                         
*Aug 11 02:27:21.175: RADIUS/ENCODE(00000007):Orig. component type = AGW

*Aug 11 02:27:21.175: RADIUS/ENCODE: NAS PORT sending disabled

*Aug 11 02:27:21.175: RADIUS(00000007): Config NAS IP: 0.0.0.0

*Aug 11 02:27:21.175: RADIUS(00000007): sending

*Aug 11 02:27:21.175: RADIUS/ENCODE: Best Local IP-Address 2.2.2.2 for

 Radius-Server 1.8.91.8

Here is sample RADIUS output for a AAA accounting stop:

*Feb 18 15:30:29.011: RADIUS(00000006): Send Accounting-Request to

 172.19.25.8:1646 id 1646/24, len 252

*Feb 18 15:30:29.011: RADIUS:  authenticator 6D FC 9B 49 59 28 56 41 - 3F 2E A5

 3C 7B 7A 3A B1

*Feb 18 15:30:29.011: RADIUS:  Acct-Session-Id     [44]  10  "00000008"

*Feb 18 15:30:29.011: RADIUS:  Framed-Protocol     [7]   6   noval0

[0]

*Feb 18 15:30:29.011: RADIUS:  Called-Station-Id   [30]  9   "2.2.2.2"

*Feb 18 15:30:29.011: RADIUS:  Framed-IP-Address   [8]   6   2.2.0.2                   
*Feb 18 15:30:29.011: RADIUS:  Calling-Station-Id  [31]  19  "06-76-22-24-22-22"

*Feb 18 15:30:29.011: RADIUS:  Vendor, Wimax       [26]  10

*Feb 18 15:30:29.011: RADIUS:   AAA-Session-ID     [4]   4

*Feb 18 15:30:29.011: RADIUS:   00 00

[??]

*Feb 18 15:30:29.011: RADIUS:  User-Name           [1]   23  "eap-md5-u@eap-

 md5.com"

*Feb 18 15:30:29.011: RADIUS:  Acct-Input-Octets   [42]  6   0                         
*Feb 18 15:30:29.011: RADIUS:  Acct-Output-Octets  [43]  6   0                         
*Feb 18 15:30:29.011: RADIUS:  Acct-Input-Packets  [47]  6   0                         
*Feb 18 15:30:29.011: RADIUS:  Acct-Output-Packets [48]  6   0                         
*Feb 18 15:30:29.011: RADIUS:  Multilink-Session-ID[50]  10  "30313233"

*Feb 18 15:30:29.011: RADIUS:  Class               [25]  21

*Feb 18 15:30:29.011: RADIUS:   63 6C 61 73 73 2D 77 69 6D 61 78 2D 63 68 61 6E  
[class-wimax-chan]

*Feb 18 15:30:29.011: RADIUS:   67 65 64

[ged]

*Feb 18 15:30:29.011: RADIUS:  Vendor, Wimax       [26]  13

*Feb 18 15:30:29.011: RADIUS:   GMT-Time-Zone-Offse[3]   7

*Feb 18 15:30:29.011: RADIUS:   00 00 00 00 00

[?????]

*Feb 18 15:30:29.011: RADIUS:  Vendor, Wimax       [26]  17

*Feb 18 15:30:29.011: RADIUS:   BaseStation-ID     [46]  11

*Feb 18 15:30:29.011: RADIUS:   00 0A 01 01 46 00 00 00 00                       
[????F????]

*Feb 18 15:30:29.011: RADIUS:  Vendor, Wimax       [26]  11

*Feb 18 15:30:29.011: RADIUS:   Packet-Data-Flow-ID[26]  5

*Feb 18 15:30:29.011: RADIUS:   00 05 01

[???]

*Feb 18 15:30:29.011: RADIUS:  Acct-Session-Time   [46]  6   25

*Feb 18 15:30:29.011: RADIUS:  Acct-Terminate-Cause[49]  6   none

[0]

*Feb 18 15:30:29.011: RADIUS:  Acct-Status-Type    [40]  6   Stop

[2]

*Feb 18 15:30:29.011: RADIUS:  NAS-Port-Type       [61]  6   802.16e Wimax             
[27]

*Feb 18 15:30:29.011: RADIUS:  NAS-Port-Id         [87]  11  "WiMAX-AGW"

*Feb 18 15:30:29.011: RADIUS:  Service-Type        [6]   6   Framed

[2]

*Feb 18 15:30:29.011: RADIUS:  NAS-IP-Address      [4]   6   172.19.24.88              
*Feb 18 15:30:29.011: RADIUS:  Acct-Delay-Time     [41]  6   0                         
*Feb 18 15:30:29.019: RADIUS: Received from id 1646/23 172.19.25.8:1646, 
Accounting-response, len 20

*Feb 18 15:30:29.019: RADIUS:  authenticator 4D 1A 1B 4D C5 0E 39 FD - 36 6B 90 FF 96 21 
66 64

*Feb 18 15:30:29.019: RADIUS: Received from id 1646/24 172.19.25.8:1646, 
Accounting-response, len 20

*Feb 18 15:30:29.019: RADIUS:  authenticator EB 25 42 F1 48 2C BF 13 - 43 B0 0A 3A 7A 04 
F4 1F

WiMAX Specific VSAs

The following VSAs are specific to WiMax:

•Wimax Capability—Indicates the WiMAX release, accounting capabilities indication, Hotlining capabilities, and Idle Mode Notification capabilities of the BWG to the AAA in an Access Request.

•GMT Time Zone Offset—The current offset in seconds of the local time at the NAS with respect to GMT time.

•Packet Data Flow-Id (PDFID)—The value of this attribute matches all records from the same packet data flow. PDFID is assigned by the CSN, and remains constant through all handover scenarios. In Release 1.0 and above, the BWG generates the PDFID for a flow in the session.

•Base Station ID—Uniquely identifies a NAP and a base station within that NAP. The BWG forwards the R6 BS ID in this attribute.

•AAA Session ID—A unique per realm identifier assigned to the WiMAX session by the home network during network entry. The value is included in all subsequent AAA packets for that session.

Handoffs

Multiple forms of handoff are supported for WiMax, both inter-base station and inter-BWG. BWG Release 1.0 and above only supports inter-base station handoff.

Inter-BS handoff includes both uncontrolled and controlled handoffs. In the controlled case, the target BS has obtained the session information from the serving BS through R8 interface before the handoff actually occurs. Uncontrolled handoffs occur where information exchange between base stations is not possible prior to the target BS triggering a handoff at the BWG. Uncontrolled handover is treated identically to Initial Network Entry, with the addition that the BWG ensures that paths registered with the serving base station are deregistered. The only addition being that for Release 1.0 and above, one attempt is made to send the deregistration message to the serving BS, and the handoff takes place regardless of the completion of the deregistration handshake between the ASN and SBS

Handoffs do not trigger interim accounting updates.

Uncontrolled Handoff

An uncontrolled handover is signaled from the BS to the BWG using a Path Registration Request message. This message contains information for each service flow that is already established with the source BS. It also contains the DP-IDs used for downlink flows.

Note There is no need to re-authenticate the device or the subscriber, as the session is maintained at the same BWG.

Note In uncontrolled handoff, the target BS will trigger a MS network entry in which the MS will get authenticated.

The BWG initiates the deregistration of the path to the old BS. This deregistration will be scheduled by the BWG. It does not necessarily occur directly after successful completion of handoff to the new BS.

There is no requirement to buffer bearer path data during handoff. Downlink data received at the BWG during the handover procedure is discarded.

Any traffic that is "in-flight" through the old path is lost because the device has already moved to the service area of the target BS before to the handoff trigger is received at the BWG.

It is possible that the device may move to a new BS while the handoff procedures between the target BS and the BWG are completed. Because the handover is uncontrolled, the handoff to the current target BS is completed (including R6 message retransmissions, if necessary) before the new handoff event is processed.

The handover exchange comprises three messages (applicable only for controlled handoff):

•Path Registration Request—sent from the Target BS to the BWG—which contains the following:

–Registration Type

–SF INFO(s) with SFID, Reservation Action (set to Create), Direction, QoS parameters, Data Path Info and GRE Key (for downlink flows)

–BS INFO with BSID

•Path Registration Response—sent from the BWG to the Target BSq—which contains the following:

–Registration Type

–SF INFO(s) with SFID, Reservation Action (set to Success), Direction, Data Path Info & GRE Key (for uplink flows)

–BS INFO with BSID

•Path Registration Acknowledgement—sent from the Target BS to the BWG—which contains the following:

–Registration Type

If the BWG cannot accept the handover, it sends the response with "reject cause code TLV".

If the BWG accepts the handover for only a subset of the desired Service Flows, the handover is rejected.

Handoff will not be rejected if secondary flow is missing, but if primary flow is missing it will be rejected.

The Deregistration Request and ACK sent to SBS will have the registration type as "Handover" while Deregistration response from SBS will have "Network exit". This is an expected behavior. On receiving this, the BWG does not send the ACK with "reject cause code TLV".

Controlled Handoff

A controlled handoff occurs when the current and target BSs are able to communicate information and exchange details about service flows, classifiers, and other details, prior to the target BS triggering the handoff at the BWG. This means that the target BS has all relevant information about the mobile device prior to sending the BWG handoff trigger. This trigger occurs when the mobile device has already been connected to the target BS using 802.16e procedures. You can tell a controlled handoff occurred at the BWG by the receipt of a Path Registration Request message from the BS without a previous authentication exchange (which would be observed for a Network Entry event).

The following flow sequence illustrates the events that occur during a controlled handoff:

Step 1 The Target Base Station sends a Path Registration Request to the BWG containing the service flow information received from the Serving Base Station.

Step 2 The BWG responds with a Path Registration Response accepting registration of the data path with the Target base Station.

Step 3 The Target Base Station responds with a Path Registration Acknowledgement.

Step 4 The BWG sends a Path Deregistration Request to the Serving Base Station.

Step 5 The Serving Base Station responds with a Path Deregistration Response.

Step 6 The BWG acknowledges the response with a Path Deregistration Acknowledgement.

Step 7 The Target Base Station sends a Context Report to the BWG.

Step 8 The BWG acknowledges with a Context Acknowledgement.

Step 9 The target BS sends a CMAC Key Count Update message, and the BWG responds with a CMAC Key Count Ack message.

Verifying the Configuration

To view the handoff statistics for the BWG, use the show wimax agw statistics section handoff command.

Here is a sample configuration:

Router#show wimax agw statistics section handoff

Message type Successful Handoff

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Registration Request

   Number of messages sent 0

   Number of messages received 2

   Number of messages resent 0

  Message type Handoff Registration Response

   Number of messages sent 2

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Registration Ack

   Number of messages sent 0

   Number of messages received 2

   Number of messages resent 0

  Message type Handoff Deregistration Request

   Number of messages sent 2

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Deregistration Response

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Handoff Deregistration Ack

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

Security Context Exchange

In order for a BS to secure the airlink, it requires keying material from the BWG. A handoff cannot be successful from the perspective of the BS and the device until the data path registration has completed, and the BS receives the keying material. The BS is responsible to initiate both procedures. The BWG treats a context exchange with the BS as an entirely separate event from handover.

A context exchange can occur at any time. The AK transfer protocol is used to transfer the keying material to the BS. This material comprises the AK, AKID, AK Lifetime, AK sequence number and EIK.

If the PMK has expired, then a new PMK must be created.

The security context exchange comprises two messages.

•Context Request—sent from the target BS to the BWG—which contains the following:

–Context Purpose Identifier

–BS Info

–Target BS ID

•Context Report—sent from the BWG to the target BS—which contains the following:

–MS Info

–AK Context

–AKID

–AK lifetime

–AK SN

–CMAC Key count

–Target BS Info

–Target BS ID

Keepalive Support for R6 Interface

The keepalive mechanism is based on the periodic transmission of "keepalive" messages between the BS and the BWG.

Transmission of the keepalive messaging is configurable at the BWG.

Note When a Base Station BWG receives an R6 Keepalive Request message, it must send an R6 Keepalive reply.

For each R6 instance, BWG maintains the following configurable parameters:

•Tk: Keepalive timer

•N: Number of consecutive keepalive failures. Initialized to 0

•M: Permitted maximum number of consecutive keepalive failures.

The supported keepalive functionality in this release is as follows:

Step 1 The base station or BWG sends a Keepalive_Request and starts timer Tk.

Step 2 On receipt of a Keepalive_Reply, the value of N is reset to 0.

Step 3 When Tk expires, the node sends the next Keepalive_Request. N is incremented if a Keepalive_Reply for the last Keepalive_Request message was not received prior to expiry of timer Tk.

Step 4 When N equals M, N is reset to 0 and any R6 sessions established with the remote node are terminated locally (with no attempt to send any further cleanup message to remote end) and any data related to subscribers, belonging to the specific R6 interface is cleaned up.

The following two TLVs will be used in this release:

•BS ID TLV to identify the BS which is either a recipient or initiator of the request.

•BWG ID to identify the BWG which is either the recipient or initiator of the request.

Keepalive Mechanism Failover Handling

While BS and BWG are in operation, suppose one or both of these units experienced a failover condition (rebooted), without any intervention from the operator, BS and BWG may get out of synchronization with respect to the registered subscribers and their states.

Solution

The Mechanism uses Keepalive messaging/Reset-Time TLV to recover from such condition immediately after such a failover.

BWG Reboots:

If a Keepalive_Request is the first message the rebooted BWG receives from the BS assuming keepalive are enabled on the latter, the BWG responds by a Keepalive_Reply with Reset-Time TLV. It indicates the reset time of the BWG and signals the BS to begin the process of deregistering all subscribers that are associated with this BWG.

If a Pre-attachment_Request is the first message the rebooted BWG receives from the BS as a result of a network entry, the former sends a Keepalive_Request with Reset-Time TLV to the BS which should take the corrective approach of clearing all subscribers.

BS Reboots:

If the BWG receives a Keepalive_Request with Reset-Time TLV from a BS which reset time is different than the BWG boot time, the former clears all the subscribers associated with this BS.

Configuring Keepalive

To configure the keepalive value on the BWG, perform the following task:


	Command	Purpose
Step 1	router(config)# wimax agw base-station group name	Configures a base-station group, and enters user into the BWG basestation configuration submode. All of the individual base stations configured to belong to this base station group use the base station group parameters. The no version of this command deletes the base station group. The base station group can only be deleted if all the references to this group are also deleted.
Step 2	router(config-wimax-agw-bs)# reference-point r6 keepalive	Specifies if keepalive packets between the BWG and BS are enabled. Default is not enabled.
Step 3	router(config-wimax-agw-bs)# reference-point r6 keepalive timeout interval-in-minutes	Specifies the keepalive interval in seconds. If this command is not configured, then the keepalive interval is set to the default value (60 seconds).
Step 4	Router(config-wimax-agw-bs)#reference-point r6 path purge-timeout	Configures the path purge timer value in minutes. As soon as the last session associates with the BS path goes away, the path purge timer is started to remove the path after the timer expiry.

Configuration Example

Here is a sample configuration of the Keepalive configuration commands:

wimax agw base-station group default

  reference-point r6 keepalive timeout 30

  reference-point r6 response retransmit 10

  reference-point r6 response timeout 10

Here is a configuration example of the reference-point r6 path purge-timeout command:

Router(config)#wimax agw base-station group default

Router(config-wimax-agw-bs)#reference-point r6 ?

  keepalive  Enable AGW-BS keepalive feature

  path       WiMAX AGW BS R6 reference point base station path

  response   WiMAX AGW BS R6 reference point response configuration commands

Router(config-wimax-agw-bs)#reference-point r6 path ?

  purge-timeout  WiMAX AGW BS R6 reference point path purge timeout

Router(config-wimax-agw-bs)#reference-point r6 path purge-timeout ?

  <1-4320>  WiMAX AGW BS R6 reference point path purge timeout in minutes

Router(config-wimax-agw-bs)#reference-point r6 path purge-timeout 30

Verifying the Configuration

To verify various BWG system parameters, perform the following tasks:


	Command	Purpose
Step 1	Router#show wimax agw	Displays various system parameters, including BWG software version, number of base stations allowed, number of subscribers allowed, number of flows, and others.
Step 2	Router#show wimax agw path 10.1.1.70	Displays base station information.
Step 3	Router#show wimax agw subscriber brief	Displays subscriber information.

Configuration Examples

Here is a sample configuration that identifies the BWG keepalive statistics:

Router#show wimax agw statistics | section Keepalive

Message function type Keepalive(20/0x14)

  Message type Keepalive Request(1/0x1)

   Number of messages sent 21

   Number of messages received 0

   Number of messages resent 0

  Message type Keepalive Response(2/0x2)

   Number of messages sent 0

   Number of messages received 21

   Number of messages resent 0

Here is a sample configuration that identifies generic BWG statistics:

Router#show wimax agw

Access network gateway version 1.0, service is enabled

 Signaling UDP port 2231

 Maximum Number of base station 500 allowed

 Maximum Number of subscriber 20000 allowed

  Current number of signalling paths 1

  Current number of data paths 1

  Current number of subscribers 3

  Current number of sessions 3

  Current number of flows 6

  Current number of hosts 0

  Traffic Sent 6 packets, 1998 bytes

  Traffic Rcvd 7 packets, 4228 bytes

Here is a sample configuration that identifies BWG base station statistics:

Router#show wimax agw path 10.1.1.70

Path type Sig-UDP

 State current Ready, old Idle

 Number of sessions connected 3

 Number of old sessions connected 0

 Address local 2.2.2.2(AF_INET), remote 10.1.1.70(AF_INET)

 UDP port local 2231(0x8B7), remote 2231(0x8B7)

 Identification, Our 0x02020202

 Keepalive timer expires in 00:00:25, timeout 30 secs

 Keepalive consecutive failures max allowed 5, current 0

 Keepalive Request received valid 0, invalid 0

 Keepalive Response received valid 11, invalid 0

 Keepalive Request sent success 11, fail 0

 Keepalive Response sent success 0, fail 0

 Traffic sent 29 packets, 3175 bytes

 Traffic received 28 packets, 2658 bytes

Path type Data-GRE

 Number of flows connected 6

 Address local 2.2.2.2(AF_INET), remote 10.1.1.70(AF_INET)

 Traffic sent 6 packets, 2166 bytes

 Traffic received 7 packets, 4522 bytes

Here is a sample configuration that identifies BWG subscriber statistics:

Router#show wimax agw subscriber brief

MSID           Address         Age       Flows Hosts Pkts-Tx    Pkts-Rx

1000.2223.0001 2.2.0.75        000.22.08 2     0     2          3

1111.1113.1111 2.2.0.74        000.22.05 2     0     2          2

1000.2225.0001 2.2.0.76        000.21.56 2     0     2          2

Session Redundancy

Note BWG Session redundancy is not supported on the Cisco 7301 Router platform.

The BWG Session Redundancy architecture provides user session failover capability in a 1:1 redundancy model, with a standby present for every active BWG. The active BWG sends state information to the standby BWG for state synchronization on a as needed basis. When an active BWG failure occurs, the standby BWG has state information needed to provide service to all existing sessions. It then takes over as the active BWG and begins servicing user sessions, thus providing session redundancy. When the previously active BWG comes back online, it takes over as standby for the now active BWG, and obtains state information for all existing sessions from it.

The BWG is hosted on the SAMI blade, and only card to card redundancy will be supported. In other words, failure of a single processor unit on SAMI will result in the entire card being switched over.

Note In Cisco BWG Release 1.1, session redundancy is still supported. However, the configuration on both standby and active should be identical regarding classifier information and CS-Type information for each service flow direction. The new fields introduced for the host data structure are synced from the active to the standby.

BWG Session Redundancy and High Availability Infrastructure

The BWG Session Redundancy is based on the Cisco IOS Hot Standby Routing Protocol (HSRP), the Cisco IOS Check-point Facility (CF) and Redundancy Framework (RF), and Stream Control Transmission Protocol (SCTP) to provide inter-device redundancy and high availability. The Figure 2-1 shows the system view of the BWG SR with relation to the IOS HA infrastructure.

Figure 2-1 Session Redundancy on the BWG

Subscriber Management

Subscriber information includes session and flows associated with a subscriber context, and is created, updated, or eventually deleted.

Subscriber information includes the following details:

•Authentication info (method, keying info, etc.)

•Addressing info (MS MAC, assigned DHCP address, etc.)

•VRF name

•Username

•Session info (signaling address, and associated timers, etc.

•Flow info per session (and associated QoS info per flow)

DHCP and AAA

The BWG supports DHCP relay mode and keeps track of client IP addresses allocated by DHCP servers (and the associated server IP addresses) so that it can relay future DHCP messages from clients to the servers. The client IP address and DHCP server IP address are saved in the subscriber context and are synced to the standby. Once the standby becomes active, it continues to relay DHCP messages from a client to the right server (there can be multiple servers configured: primary/secondary).

IOS AAA is not HA-aware at the moment, so the sync of AAA-related information is part of the session replication.

Dynamic Synchronization

In order for the standby to take over processing from the active in case of a failure, information regarding all sessions and flows on the active are dynamically synchronized to the standby at well defined synchronization points. Separate TLVs are used to synchronize session, flow, and path related information. Dynamic syncing happens for new session/flow events after the standby is at hot-standby state, and after bulk-sync is complete.

The following list identifies current synchronization points:

•During initial network entry, session and flow information is synched to standby only after the Initial Service Flow (ISF) is created.

•After the ISF is up, each new flow created on the active is separately synched to the standby.

•Any updates to the service flow will cause the flow to be synched to the standby.

•Every time an address allocation happens, the flow will be synched to the standby.

•Any changes to the path on the active are synchronized to the standby

•During handoff, flow information is synchronized to the standby only after the handoff is complete. Cloned flows are not synched. New flows created on the active as a result of handoff are synchronized to standby by a FLOW UPDATE message that carries modified parameters as result of handoff.

•Flow synchronization after the transmission of an interim accounting request from the active. This causes FLOW UPDATE messages to be sent from active to standby, and the necessary message carries accounting counters that are sent to AAA as a part of interim accounting update.

Configuring Session Redundancy

The following configuration tasks are required before you can configure session redundancy:

•Configure HSRP on the interface.

•Configure redundancy inter-device

•Configure SCTP for RF Check pointing

•Configure Network Time Protocol (NTP) server

•Configure AAA on the active BWG and standby BWG

To configure session redundancy on the BWG, perform the following tasks:


	Command	Purpose
Step 1	Router#interface FastEthernet0/1 description BS-If ip address 9.11.44.147 255.255.255.0 standby 100 ip 9.11.44.100 standby 100 name CORE	Configures HSRP on the interface.
Step 2	Router# redundancy inter-device scheme standby CORE	Enters inter-device configuration mode, which allows you to enable and protect Stateful Switchover (SSO) traffic.
Step 3	Router#ipc zone default association 1 no shutdown protocol sctp local-port 5000 local-ip 9.11.44.147 remote-port 5000 remote-ip 9.11.44.159	Configures SCTP for RF Check pointing.
Step 4	Router#config terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#ntp server 129.237.32.2 Router(config)#^Z	(Recommended) - The command ntp server, followed by the IP address or hostname of the NTP server, is used to configure your router to use an existing NTP server
Step 5	Router(config)#ip radius source-interface Loopback Loopback number and configure the loopback interface on your router as follows: interface Loopback0 ip address 192.168.0.250 255.255.255.255	Configuring ip radius source-interface Loopback on both BWGs enables a AAA server to view two BWGs as a single entity.
Step 6	Router(config)# wimax agw redundancy	Enables session redundancy on the BWG.
Step 7	Router(config)# subscriber redundancy rate 500 1	Specifies the sync rate for SR.

Configuration Example

This configuration is for AAA only.

On the active BWG

---------------------------------------------------------------

interface Loopback192

 ip address 192.168.0.70 255.255.255.255

aaa group server radius car-sg

 server 1.8.70.99 auth-port 1812 acct-port 1813

aaa authentication dot1x car_auth_list group car-sg

aaa accounting network car_acct_list start-stop group car-sg

ip radius source-interface Loopback192

radius-server host 1.8.70.99 auth-port 1812 acct-port 1813

radius-server key r6AAA

radius-server vsa send accounting wimax

radius-server vsa send authentication wimax

On the Standby BWG

---------------------------------------------------------------

interface Loopback192

 ip address 192.168.0.70 255.255.255.255

aaa new-model

aaa group server radius car-sg

 server 1.8.70.99 auth-port 1812 acct-port 1813

aaa authentication dot1x car_auth_list group car-sg

aaa accounting network car_acct_list start-stop group car-sg

ip radius source-interface Loopback192

radius-server host 1.8.70.99 auth-port 1812 acct-port 1813

radius-server key r6AAA

radius-server vsa send accounting wimax

radius-server vsa send authentication wimax

Sample Configuration of BWG: Active

			interface GigabitEthernet0/0.70

              description to AAA/DHCP

 encapsulation dot1Q 70

 ip address 1.8.70.147 255.255.255.0

 standby 70 ip 1.8.70.70

 standby 70 follow P7_REDUNDANCY

Note Please reload the BWG if it suffers a time-zone change.

This configuration example includes information about DHCP:

interface Loopback102

    ip address 102.0.0.1 255.255.255.0

   user-group domain eaptls.com2

   aaa accounting method-list AAA-ACC1

   aaa authentication method-list AAA-AUTHN1

   dhcp gateway address 102.0.0.1

   dhcp server primary 27.0.0.8

   service-flow pre-defined isf profile sf3

   service-flow pre-defined secondary 1 profile sf4

   vrf VRF_2

Authentication

A subscriber is authenticated using EAP on the active before the sessions/flows are recreated on the standby. The associated MSK, AK context and other credentials need to be transferred to the standby, along with the session stateful data. If geographic redundancy is deployed, this data must be protected. If the standby becomes active after a switchover, and if the same subscriber is re-authenticated on the new active, it follows the same authentication procedure as on the previous active.

Accounting

The accounting start, stop and interim update are only sent from the active. The standby never sends accounting records until it becomes active.

As part of the session/flow recreation on the standby, the IOS AAA database is populated with accounting records for each session/flow. For example, the "class" attribute and accounting session ID are synched from the active to the standby, and are saved to the related accounting record. This ensures that once the standby becomes active, it can send accounting records with the right info.

Synchronization of accounting counters is a function of the AAA interim accounting update feature. If the AAA interim accounting update feature is enabled, then the active BWG sends accounting records to AAA server. And the same event is used as a trigger to initiate a FLOW UPDATE event (which carries accounting counters the same as were sent to AAA server). Conversely, if this feature is disabled on the active, since there is not going to be an accounting update to AAA, there is an absence of triggers to send the accounting update synchronization message to standby. By itself, the BWG SR feature does not implement triggers to synchronize accounting counters.

The accounting session ID is a key attribute used in accounting events (start, stop, interim) and is used to collaborate records on the AAA server. It is a 4-byte unassigned integer, and is assigned uniquely within a ASNWG and increased sequentially until it rolls over. To ensure the new active can continue to generate unique accounting session IDs upon switchover, the new accounting session ID starts from the latest accounting session ID on the prior active.

Subscriber IP Address

Currently, the subscriber IP address is assigned by the DHCP server and a host route is inserted for it. When the standby recreates the subscriber session, the same host route is also inserted on the standby. The standby will not relay any DHCP messages between the DHCP client and the server until it becomes active.

QoS

For BWG Release 1.0 and above, after a flow is created and the QoS parameters for the flow are sent to the BS, the BWG active synchronizes all the QoS parameters to the standby. Out of all of the parameters, the DSCP code for a flow synched to the standby is used to mark the packets once it becomes active.

Statistics and Counters

Statistics and counters are not synched to the standby. Instead, the standby rebuilds them as it processes stateful data from the active to create, modify, and delete sessions/flows. For example, the number of sessions/flows on the standby is updated as the standby processes session/flow creation and deletion. The number of received R6 messages on the standby is accumulated from the moment it becomes active and starts to receive R6 messages.

BWG Load Balancing

When a load balancer is running, it uses the loading information of all the BWGs to select one of them, and forwards an incoming NetEntry message from the BS (with regard to a SS/MS) to the selected BWG.

When Dynamic Feedback Protocol (DFP) is configured, an active BWG periodically sends its loading information to the load balancer. A standby BWG does not send feedback and does not have accurate loading information because it does not process R6 messages and handle user traffic. Once a standby becomes active, it gradually builds accurate load as it processes R6 messages and handles user traffic. So there is an adjusting period before it can send back feedback about its current accurate load.

Data Path and GRE

The data path for a flow is recreated on the standby. The GRE keys for both the upstream and downstream of a flow are synched to the standby. Upon switchover, the new active ensures that any new GRE key allocated locally must not collide with any in-use GRE keys allocated by the previous active.

Version Control

Upgrading from the immediate lower software version to a higher version is supported. Downgrading of software version is not supported. For example, if a redundant pair of BWGs runs on version A, and the next immediate software version is version B, then upgrading from version A to B is supported (but not from B to A). This requires that the higher version understands the stateful data synched from a lower version.

Limitations

The following limitations exist in the Session Redundancy feature on the BWG:

•Synchronization of Accounting Counters

This is configurable, and depends upon the AAA interim accounting update feature to be enabled. If the AAA interim accounting feature is disabled, then the default behavior of BWG SR is to not synchronize accounting data/payload counters. This may lead to under charging. For example, if a switchover occurs between two consecutive interim updates, the counts accumulated on the active after the previous interim update are lost, since the new interim update sends only the counts that are accumulated on the new active. Additionally, a STOP could be lost right before the switchover.

Note Signaling counters are not synched.

Note For a standalone system, current AAA/Radius counters work accurately. However, when Session Redundancy is enabled, the flow (or session in terms of radius) age can be incorrect if relied upon the current counters. An additional attribute will now be sent from the ASN-GW called "session_elapsed_time" which will reflect the number of seconds since the particular flow started.

•Missing of a Session on the Standby

Although SCTP provides reliable transport, the stateful data used to replicate a session can be lost due to congestion or max retrials. In this case, the session is not recreated on the standby. In case there is a switchover, this session is lost.

•Stale Session on the Standby

For the same reason as above, if a stateful data for a session deletion is lost, then the session is not deleted from the standby while it's gone on the active.

–If there is no switchover before the next session creation of the same subscriber, it's expected that the next synching of creation of a new session for the same subscriber will clean up the stale session.

–If there is a switchover, then the stale session hangs until cleanup by manual intervention or by features like idle/session timeout.

•Mid-call Abort

If a call setup is in progression but before reaching the first synching point and if there is a switchover, the call setup is aborted, and the subscriber has to retry the call.

Switchover

When switchover occurs, a trap is generated and sent to the NMS system to indicate that the active unit has failed, and the standby has taken over as active. The following behavior is expected:

•Any new GRE key allocated locally must not collide with any in-use GRE keys allocated by the previous active.

•Any new accounting session ID allocated locally must not collide with any in-use accounting session ID allocated by the previous active.

•DHCP relay for a new session is forwarded to a configured DHCP server.

•Some of the statistics will have a fresh start.

•DFP load is rebuilt and sent to the load balancer.

The following list identifies events which will cause a switchover:

•Router reload/crash because of reasons like software crash, CPU hogging, etc.

•HSRP tracks interfaces based on the configuration. On detecting interface flap <on-off transition> HSRP will enforce reload current active which will cause switchover of activity

•Manual intervention to switch activity from current active router to redundant hot standby. This can be accomplished using the following commands:

–redundancy switch-activity force

This command is used to switch activity from current active to current hot standby. Issuing the command causes the current router to reload, the current hot standby to become active, and when the current active router comes back up it assumes the role of hot standby.

–reload

This is normal router reload command that causes switchover. The current active router will reload, and the current hot standby will become active.

BWG Load Balancing

The purpose of load balancing is scalability of the BWG without distributing intelligence across base stations. This scalability is provided by load balancing across a set of BWGs, while representing the cluster as a single BWG from the perspective of the BS. Thus, the base station will have a single point of contact. And any new BWG that is added to the system will not impact the base station provisioning.

Note Server Load Balancing and Session Redundancy are only available on Cisco 7600 SAMI platform. They are not available on the Cisco 7301 router platform.

BWG Load Balancing is based on the IOS Server Load Balancing (SLB) feature. BSs are configured with the virtual IP address of the SLB as the BWG ID. The BWG selection flow for load balancing is illustrated below. Both dispatch mode and directed mode are supported. DFP is supported for the SLB to discover the load on the real BWGs.

Note In Release 1.0 and above, the SLB sticky feature and BWG handover call flows are not supported.

The session created on SLB, when the initial context request is processed, is maintained for a configurable time period to handle the re-transmission. During this period, if a re-transmission of context request is detected for a given MS/SS, SLB directs the re-transmission request to the same real BWG, that was selected for the first context request.

DFP is supported for the SLB to discover the load on the real BWGs. Each real BWG has a limit on the number of maximum sessions it supports. Real BWG calculated load on itself is based on the existing number of sessions versus the maximum sessions that it can support, memory usage, and bandwidth usage and reports the load to SLB. SLB directs the initial context request to one of the real BWGs based on either the round robin or least connections method. An BWG will not accept any more sessions if its load as calculated by DFP is 100%. Thus, this mechanism also supports CAC.

Figure 2-2 Server Load Balancing on the BWG

BWG Selection

•During Initial Network Entry phase, the BS sends the NetEntry MS Pre-Attachment Request corresponding to the SS/MSS to the BWG configured as the default.

•This BWG sends the NetEntry MS Pre-Attachment Response to the BS. The response may contain the IP address of an alternate Authenticator ID that can handle subsequent transactions corresponding to the SS/MSS. The BS, on receiving the NetEntry MS Pre-Attachment Response, sends the NetEntry MS State Change Ack to complete the transaction.

•All subsequent transactions corresponding to the SS/MSS occur between the BS and the BWG specified in the NetEntry MS Pre-Attachment Response Message.

Modes of Operation

There are two operation modes on the BWG:

•Dispatched Mode— In this mode packets are sent to the real server without any change to the original packet. A loopback is configured in the real server with an IP equal to virtual IP, and it replies back with virtual IP address as the source address.

•Directed Mode—The packet's destination IP address is rewritten to choose the BWG's IP address, and no loopback with the virtual ip address is configured on the BWG.

In both modes the selected BWG sends the pre-attachment response.

Configuring Load Balancing

This section lists configuration details regarding server load balancing. These configuration details are mainly for Directed Mode unless otherwise specified.

Load Balancing Configuration Task List

This section lists the tasks used to configure load balancing. Required and optional tasks

are indicated.

1. On the Cisco IOS SLB, complete the following tasks:

a. Configuring a Server Farm and Real Server, (Required)

b. Configuring a Virtual Server, (Required)

c. Configuring DFP Support, (Optional, but recommended)

2. On the real BWG, complete the following tasks:

a. Configuring a Loopback Interface for SLB, (Required if using dispatched mode)

b. Configuring DFP Support on the BWG, (Optional, but recommended)

Configuring Cisco IOS SLB for Load Balancing

This section describes how to configure a Server Farm and a Real Server. To configure a Cisco IOS SLB server farm, use the following commands, beginning in global configuration mode:


	Command	Purpose
Step 1	Router-SLB(config)# ip slb serverfarm serverfarm-name Router(config-slb-sfarm)#	Adds a server farm definition to the Cisco IOS SLB configuration, and enters server farm configuration mode.
Step 2	Router-SLB(config-slb-sfarm)# nat server	Configures NAT server address translation mode on the server farm.
Step 3	Router-SLB(config-slb-sfarm)# real ip-address [port]	Identifies a real BWG as a member of a server farm, using the IP address of the BWG's virtual template interface, and enters real server configuration mode.
Step 4	Router-SLB(config-slb-real)# weight weighting-value	(Optional) Specifies the real server's workload capacity relative to other servers in the server farm. Note If you use DFP, the static weights you define using the weight (server farm) command are overridden by the weights calculated by DFP. If DFP is removed from the network, Cisco IOS SLB reverts to the static weights.
Step 5	Router-SLB(config-slb-real)# in service	Enables the real server for use by Cisco IOS SLB.

Sample Configuration

ip slb serverfarm ASNGW-SR-SF

       nat server

 probe PINGPROBE

 real 11.11.11.50

   weight 0

  		   inservice

 		 real 11.11.11.70

 		   weight 0

               inservice

Configuring Real BWG

Configuring the BWG for Load Balancing

To configure load balancing on the BWG, complete the tasks in the following sections:

•Configuring a Loopback Interface for SLB,

•Configuring the BWG as a DFP Agent, (Optional, but recommended)

Configuring a Loopback Interface for SLB

To enable load balancing, a loopback interface must be configured with the same IP address as thevirtual server on the Cisco IOS SLB on each BWG in a farm.

To create a loopback interface, use the following commands, beginning in global configuration mode:


	Command	Description
Step 1	Router(config)# interface loopback number	Creates a loopback interface. A loopback interface is a virtual interface that is always up
Step 2	Router(config-if)# ip address ip-address mask	Assigns an IP address to the loopback interface.

Configuring the BWG as a DFP Agent

To define the port number to be used by the DFP manager (the Cisco IOS SLB in this instance) to connect to the DFP agent; enter the following commands in order, beginning in global configuration mode:


	Command	Description
Step 1	Router-ASNGW(config)# ip dfp agent agw	Identifies a DFP agent subsystem and initiates DFP agent configuration mode.
Step 2	Router- ASNGW(config-dfp)# port port-number	Defines the port number to be used by the DFP manager to connect to the DFP agent.
Step 3	Router- ASNGW(config-dfp)# inservice	Enables the DFP agent for communication with a DFP manager. A DFP agent is inactive until both of the following conditions are met: •The DFP agent has been enabled using the inservice (DFP agent) command. •The client subsystem has changed the DFP agent

Sample Configuration

ip dfp agent agw

	port 5555

	inservice

To configure load balancing on the BWG, perform the following task:


	Command	Purpose
Step 1	Router# virtual x.y.z.m udp port no service asnr6	Enables load balancing on the BWG. The virtual server configuration commands are extended for ASN support.
Step 2	Router# idle asnr6 request timer value in seconds	Sets the idle timer request for the BWG.

BWG Configuration Example

Please note that following sample configuration applies only to SAMI platform.

SLB Related Configuration of Supervisor Card

7606-R6-sup720#show running-configuration | section slb

ip dfp agent slb

 port 5555

ip slb probe PINGPROBE ping

 interval 3

 faildetect 3

ip slb serverfarm ASNGW-SR-SF

 nat server

 probe PINGPROBE

 real 11.11.11.50

  weight 0

  inservice

 real 11.11.11.70

  weight 0

  inservice

ip slb vserver V-ASNGW-SR

 virtual 50.70.80.100 udp 2231 service asn r6

 serverfarm ASNGW-SR-SF

 idle asn r6 request 90

 inservice

ip slb dfp

 agent 11.11.11.50 5555 10 0 5

 agent 11.11.11.70 7777 10 0 5

7606-R6-sup720#

Sample configuration of real BWG for above configuration of Supervisor card.

asngw-real-s4p5# show running-configuration | section dfp

ip dfp agent agw

 port 5555

 inservice

asngw-real-s4p5#

asngw-real-s4p7#sh runn | section dfp

ip dfp agent agw

 port 7777

 inservice

asngw-real-s4p7#

Verifying the Configuration

To verify that load balancing is enabled on the BWG, perform the following tasks:


	Command	Purpose
Step 1	Router# show ip slb session asnr6 [detail]	Displays statistics related to load balancing R6 sessions.
Step 2	Router# show ip slb vserver detail	Displays vserver statistics in detail.

Configuration Example

Here is a sample configuration for SLB show commands on the BWG:

7606-R6-sup720#show ip slb sessions asn r6

vserver         MSID             Base Station     real             state

----------------------------------------------------------------------------

7606-R6-sup720#show ip slb sessions asn r6

vserver         MSID             Base Station     real             state

----------------------------------------------------------------------------

V-ASNGW-SR      0000AAAAC38ECCCC 50.35.50.1       11.11.11.50      ASNR6_ESTAB

V-ASNGW-SR      0000AAAAC392CCCC 50.35.50.1       11.11.11.50      ASNR6_ESTAB

V-ASNGW-SR      0000AAAAC396CCCC 50.35.50.1       11.11.11.50      ASNR6_ESTAB

V-ASNGW-SR      0000AAAAC39ACCCC 50.35.50.1       11.11.11.50      ASNR6_ESTAB

V-ASNGW-SR      0000AAAAC39ECCCC 50.35.50.1       11.11.11.50      ASNR6_ESTAB

< S N I P P E D >

7606-R6-sup720#show ip slb vserver detail

V-ASNGW-SR, state = OPERATIONAL, v_index = 7, interface(s) = <any>

  virtual = 50.70.80.100/32:2231, UDP, service = ASNR6, advertise = TRUE

  server farm = ASNGW-SR-SF, delay = 10, idle = 3600

  asnr6: request idle = 90, Parse error pkt drops= 56,

         Number of reject responses = 0

  sticky: <none>

  sticky: group id = 0

  synguard counter = 0, synguard period = 0

  conns = 101, total conns = 509069, syns = 0,  syn drops = 0

  standby group = None

7606-R6-sup720#show ip slb reals

real                  farm name        weight  state          conns

-------------------------------------------------------------------

11.11.11.50           ASNGW-SR-SF      92      OPERATIONAL    83

11.11.11.70           ASNGW-SR-SF      92      OPERATIONAL    18

7606-R6-sup720#show ip slb serv

7606-R6-sup720#show ip slb serverfarms

server farm      predictor           nat   reals   bind id  interface(s)

--------------------------------------------------------------------------

ASNGW-SR-SF      ROUNDROBIN          S     2       0        <any>

7606-R6-sup720#show ip slb sessions asn r6 de

7606-R6-sup720#show ip slb sessions asn r6 detail

V-ASNGW-SR, client = 50.35.50.1:2231, virtual = 50.70.80.100:2231

   state = ASNR6_ESTAB, real = 11.11.11.50

   Key = 0000AAAAC38ECCCC, retry = 1

V-ASNGW-SR, client = 50.35.50.1:2231, virtual = 50.70.80.100:2231

   state = ASNR6_ESTAB, real = 11.11.11.50

   Key = 0000AAAAC392CCCC, retry = 1

V-ASNGW-SR, client = 50.35.50.1:2231, virtual = 50.70.80.100:2231

   state = ASNR6_ESTAB, real = 11.11.11.50

   Key = 0000AAAAC396CCCC, retry = 1

V-ASNGW-SR, client = 50.35.50.1:2231, virtual = 50.70.80.100:2231

   state = ASNR6_ESTAB, real = 11.11.11.50

   Key = 0000AAAAC39ACCCC, retry = 1

V-ASNGW-SR, client = 50.35.50.1:2231, virtual = 50.70.80.100:2231

   state = ASNR6_ESTAB, real = 11.11.11.50

   Key = 0000AAAAC39ECCCC, retry = 1

V-ASNGW-SR, client = 50.35.50.1:2231, virtual = 50.70.80.100:2231

   state = ASNR6_ESTAB, real = 11.11.11.50

< S N I P P E D >

7606-R6-sup720#

Configuring a Virtual Server

To configure a Cisco IOS SLB virtual server, use the following commands, beginning in global configuration mode:


	Command	Purpose
Step 1	Router-SLB(config)# ip slb vserver virtual_server-name	Identifies a virtual server, and enters virtual server configuration mode.
Step 2	Router-SLB(config-slb-vserver)# virtu al ip-addr [netmask [group]] {esp \| gre \| protocol} or Router(config-slb-vserver)# virtual ip-addr [netmask [group]] {tcp \| udp} [port \| any] [service service]	Specifies the virtual server IP address, type of connection, and optional TCP or UDP port number, Internet Key Exchange (IKE) Internet Security Association and Key Management Protocol (ISAKMP) or Wireless Session Protocol (WSP) setting, and service coupling.
Step 3	Router-SLB(config-slb-vserver)# serve rfarm primary-farm [backup backup-farm [sticky]] [map map-id priority priority]	Associates a real server farm with a virtual server. •backup—(Optional) Configures a backup server farm •backup backup-farm [sticky]—(Optional) Configures a backup server farm and optionally specifies that sticky connections are to be used in the backup server farm. •map map-id priority priority—(Optional) Associates an IOS SLB protocol map to a server farm and defines the priority for that map. Maps are searched based on priority. The lower the number, the higher the priority. Note Multiple instances of the serverfarm command are allowed if configured with the map keyword option. The default server farm (without the map keyword option) is limited to a single instance. Note To change map configurations the virtual server must be taken out of service. Note The NAT modes on the primary and backup server farms for each map must match.
Step 4	Router-SLB(config-slb-vserver)# idle [request] duration	(Optional) Specifies the minimum amount of time that Cisco IOS SLB maintains connection context in the absence of packet activity.
Step 5	Router-SLB(config-slb-vserver)# inservice	Enables the virtual server for use by Cisco IOS SLB.

Sample Configuration

Router-SLB(config)# ip slb vserver V-ASNGW-SR

Router-SLB(config-slb-vserver)# virtual 50.70.80.100 udp 2231 service asn r6

Router-SLB(config-slb-vserver)#serverfarm ASNGW-SR-SF

Router-SLB(config-slb-vserver)# idle asn r6 request 90

Router-SLB(config-slb-vserver)#inservice

Configuring DFP Support

You can define Cisco IOS SLB as a DFP manager, as a DFP agent for another DFP manager (such as Distributed Director), or as both at the same time. Depending on your network configuration, you might enter the commands for configuring Cisco IOS SLB as a DFP manager and the commands for configuring Cisco IOS SLB as a DFP agent on the same device or on different devices.

To configure Cisco IOS SLB as a DFP manager, and to identify a DFP agent with which Cisco IOS SLB can initiate connections, use the following commands, beginning in global configuration mode:


	Command	Description
Step 1	Router-SLB(config)# ip slb dfp [password [0\|7] password [timeout]]	Configures DFP, supplies an optional password, and enters DFP configuration mode.
Step 2	Router-SLB(config-slb-dfp)# agent ip_address port-number [timeout [retry_count [retry_interval]]]	Identifies a DFP agent to which Cisco IOS SLB can connect.

Sample Configuration

Router-SLB(config) # ip slb dfp

Router-SLB(config-slb-dfp)# agent 11.11.11.50 5555 10 0 5

Router-SLB(config-slb-dfp)# agent 11.11.11.70 7777 10 0 5

Configuring the BWG

This section describes various other configuration tasks that you need to perform to make the BWG function properly. It includes the following topics:

•Configuring SNMP on the BWG

•MIB Support

Configuring SNMP on the BWG

This section provides information on how to configure Simple Network Management Protocol (SNMP) on the BWG. It contains the following configuration tasks:

•Configuring SNMP Access in Routers

•Configuring SNMP-Server Host

•Configuring SNMP-Server Trap-Source

•Configuring SNMP Traps

Configuring SNMP Access in Routers

To set up the community access string to permit access to the Simple Network Management Protocol (SNMP), perform the following tasks:


	Command	Purpose
Step 1	router(config)# snmp-server community string [view view-name] [ro \| rw] [ipv6 nacl] [access-list-number] string view view-name ro rw ipv6 nacl access-list-number	Sets up the community access string to permit access to the Simple Network Management Protocol (SNMP). To remove the specified community string, use the no form of the command. Community string that consists of 1 to 32 alphanumeric characters and functions much like a password, permitting access to SNMP. Blank spaces are not permitted in the community string. Note The @ symbol is used for delimiting the context information. Avoid using the @ symbol as part of the SNMP community string when configuring this command. (Optional) Specifies a previously defined view. The view defines the objects available to the SNMP community. (Optional) Name of a previously defined view. (Optional) Specifies read-only access. Authorized management stations can only retrieve MIB objects. (Optional) Specifies read-write access. Authorized management stations can both retrieve and modify MIB objects. (Optional) Specifies a IPv6 named access list. (Optional) IPv6 named access list. (Optional) Integer from 1 to 99 that specifies a standard access list of IP addresses or a string (not to exceed 64 characters) that is the name of a standard access list of IP addresses allowed access to the SNMP agent. Alternatively, an integer from 1300 to 1999 that specifies a list of IP addresses in the expanded range of standard access list numbers that are allowed to use the community string to gain access to the SNMP agent.

Configuring SNMP-Server Host

To specify the recipient of an Simple Network Management Protocol notification operation, perform the following tasks:


	Command	Purpose
Step 1	router(config)# snmp-server host host-addr [traps \| informs] [version {1 \| 2c \| 3 [auth \| noauth \| priv]}] community-string [udp-port port] [notification-type]	Specifies the recipient of an Simple Network Management Protocol notification operation. To remove the specified host, use the no form of this command.

This command is disabled by default. No notifications are sent. If you enter this command with no keywords, the default is to send all trap types to the host. No informs will be sent to this host.

If no version keyword is present, the default is version 1. The no snmp-server host command with no keywords will disable traps, but not informs, to the host. In order to disable informs, use the no snmp-server host informs command.


host-addr	Name or Internet address of the host (the targeted recipient).
traps	(Optional) Send SNMP traps to this host. This is the default.
informs	(Optional) Send SNMP informs to this host.
version	(Optional) Version of the Simple Network Management Protocol (SNMP) used to send the traps. Version 3 is the most secure model, as it allows packet encryption with the priv keyword. If you use the version keyword, one of the following must be specified: 1 —SNMPv1. This option is not available with informs. 2c —SNMPv2C. 3 —SNMPv3. The following three optional keywords can follow the version 3 keyword: •auth (Optional). Enables Message Digest 5 (MD5) and Secure Hash Algorithm (SHA) packet authentication •noauth (Default). The noAuthNoPriv security level. This is the default if the [auth \| noauth \| priv] keyword choice is not specified. •priv (Optional). Enables Data Encryption Standard (DES) packet encryption (also called "privacy").
community-string	Password-like community string sent with the notification operation. Though you can set this string using the snmp-server host command by itself, we recommend you define this string using the snmp-server community command prior to using the snmp-server host command.
udp-port port	UDP port of the host to use. The default is 162.
notification-type	(Optional) Type of notification to be sent to the host. If no type is specified, all notifications are sent. The notification type can be one or more of the following keywords: •bgp—Sends Border Gateway Protocol (BGP) state change notifications. •config—Sends configuration notifications. •dspu—Sends downstream physical unit (DSPU) notifications. •entity—Sends Entity MIB modification notifications. •envmon—Sends Cisco enterprise-specific environmental monitor notifications when an environmental threshold is exceeded. •frame-relay—Sends Frame Relay notifications. •hsrp—Sends Hot Standby Routing Protocol (HSRP) notifications. •isdn—Sends Integrated Services Digital Network (ISDN) notifications. •llc2—Sends Logical Link Control, type 2 (LLC2) notifications. •repeater—Sends standard repeater (hub) notifications. •rsrb—Sends remote source-route bridging (RSRB) notifications. •rsvp—Sends Resource Reservation Protocol (RSVP) notifications. •rtr—Sends SA Agent (RTR) notifications. •sdlc—Sends Synchronous Data Link Control (SDLC) notifications. •sdllc—Sends SDLLC notifications. •snmp—Sends Simple Network Management Protocol (SNMP) notifications (as defined in RFC 1157). •stun—Sends serial tunnel (STUN) notifications. •syslog—Sends error message notifications (Cisco Syslog MIB). Specify the level of messages to be sent with the logging history level command. •tty—Sends Cisco enterprise-specific notifications when a Transmission Control Protocol (TCP) connection closes. •x25—Sends X.25 event notifications.

Configuring SNMP-Server Trap-Source

To specify the interface (and the corresponding IP address) that an Simple Network Management Protocol trap should originate from, perform the following task:


	Command	Purpose
Step 1	router(config)# snmp-server trap-source interface interface	Specifies the interface (and hence the corresponding IP address) that an Simple Network Management Protocol trap should originate from. Use the no form of the command to remove the source designation. The default setting is that no interface is specified. Interface from which the SNMP trap originates. The argument includes the interface type and number in platform-specific syntax.

Configuring SNMP Traps

To enable the router to send Simple Network Management Protocol traps or informs (SNMP notifications), perform the following task:


	Command	Purpose
Step 1	router(config)# snmp-server enable traps [notification-type] [notification-option]	Enables the router to send Simple Network Management Protocol traps or informs (SNMP notifications). The no form of this command disables SNMP notifications. This command is disabled by default. Most notification types are disabled. However, some notification types cannot be controlled with this command. If you enter this command with no notification-type keywords, the default is to enable all notification types controlled by this command (Exception: ATM PVC notifications are not enabled unless the atm pvc keywords are used.)


notification- type	(Optional) Type of notification to enable. If no type is specified, all notifications available on your device are sent. The notification type can be one of the following keywords: •atm pvc—Enables ATM permanent virtual circuit (PVC) notifications. When the atm pvc keywords are used, you can specify additional notifcation-option values (see below). The ATM PVC failure notifcation is defined as "enterprise 1.3.6.1.4.1.9.10.29.2.1; 1 atmIntfPvcFailuresTrap" in the CISCO-IETF-ATM2-PVCTRAP-MIB. ATM PVC failure notifications are sent when a PVC on an ATM interface fails or leaves the UP operational state. Only one trap is generated per hardware interface, within the specified interval defined by the interval keyword (stored as the atmIntfPvcNotificationInterval in the MIB). If other PVCs on the same interface go DOWN during this interval, traps are generated and held until the fail-interval has elapsed. Once the interval has elapsed, the traps are sent if the PVCs are still DOWN. No notifications are generated when a PVC returns to the UP state after having been in the DOWN state. If you need to detect the recovery of PVCs, you must use the SNMP management application to regularly poll your router. •bgp—Enables Border Gateway Protocol (BGP) state change notifications. •config—Enables configuration notifications. •entity—Enables Entity MIB modification notifications. •envmon—Enables Cisco enterprise-specific environmental monitor notifications when an environmental threshold is exceeded. When the envmon keyword is used, you can specify a notification-option value. •frame-relay—Enables Frame Relay notifications. •hsrp—Enables Hot Standby Routing Protocol (HSRP) notifications. •isdn—Enables Integrated Services Digital Network (ISDN) notifications. When the isdn keyword is used, you can specify a notification-option value. •repeater—Enables Ethernet hub repeater notifications. When the repeater keyword is selected, you can specify a notification-option value. •rsvp—Enables Resource Reservation Protocol (RSVP) notifications. •rtr—Enables Service Assurance Agent / Response Time Reporter (RTR) notifications.
notification- type	•snmp [authentication]—Enables RFC 1157 SNMP notifications. Note that use of the authentication keyword produces the same effect as not using the authentication keyword. Both the snmp-server enable traps snmp and snmp-server enable traps snmp authentication forms of this command will globally enable (or, if using the no form, disable) the following SNMP traps: –authentication Failure –linkUp –linkDown –coldstart (This behavior is corrected in Cisco IOS Release 12.1(3)T and 12.0(20)S.) •syslog—Enables error message notifications (Cisco Syslog MIB). Specify the level of messages to be sent with the logging history level command.
notification- option	(Optional) •atm pvc [interval seconds] [fail-interval seconds]— The optional interval seconds keyword/argument combination specifies the minimum period between successive traps, in the range from 1 to 3600. Generation of PVC traps is dampened by the notification interval in order to prevent trap storms. No traps are sent until the interval lapses. The default interval is 30. —The optional fail-interval seconds keyword/argument combination specifies the minimum period for storing the failed time stamp, in the range from 0 to 3600. The default fail-interval is 0. •envmon [voltage \| shutdown \| supply \| fan \| temperature]—When the envmon keyword is used, you can enable a specific environmental notification type, or accept all notification types from the environmental monitor system. If no option is specified, all environmental notifications are enabled. The option can be one or more of the following keywords: voltage, shutdown, supply, fan, and temperature. •isdn [call-information \| isdn u-interface]—When the isdn keyword is used, you can specify the call-information keyword to enable an SNMP ISDN call information notification for the ISDN MIB subsystem, or you can specify the isdnu-interface keyword to enable an SNMP ISDN U interface notification for the ISDN U interface MIB subsystem. •repeater [health \| reset] —When the repeater keyword is used, you can specify the repeater option. If no option is specified, all repeater notifications are enabled. The option can be one or more of the following keywords: •health—Enables IETF Repeater Hub MIB (RFC 1516) health notification. •reset—Enables IETF Repeater Hub MIB (RFC 1516) reset notification.

Configuration Examples

The following example enables the router to send all traps to the host specified by the name "myhost.cisco.com", using the community string defined as "public":

snmp-server enable traps

snmp-server host myhost.cisco.com public

The following example enables the router to send Frame Relay and environmental monitor traps to the host "myhost.cisco.com" using the community string "public":

snmp-server enable traps frame-relay

snmp-server enable traps envmon temperature

snmp-server host myhost.cisco.com public

The following example will not send traps to any host. The BGP traps are enabled for all hosts, but the only traps enabled to be sent to a host are ISDN traps (which are not enabled in this example).

snmp-server enable traps bgp

snmp-server host bob public isdn

router(config)# [no] logging snmp-authfail

Note Using the logging snmp-authfail command enables all SNMP authentication failure logging messages. The no version of this command will disable the logging of authentication failure messages.

Note If you do not use the SNMP management tools of the router to monitor PPP sessions, you can prevent the virtual-access subinterfaces from being registered with the SNMP functionality of the router and using memory by using the no virtual-template snmp command. For example:
router(config)# [no] virtual-template snmp

SNMP Configuration Examples on the BWG

Logging

=========

logging snmp-authfail

logging queue-limit 100

logging buffered 1000000

enable password lab

Virtual Template

=============

no virtual-template snmp

SNMP Traps

==========

snmp-server community private RW

snmp-server trap-source GigabitEthernet0/2

snmp-server enable traps snmp authentication linkdown linkup coldstart warmstart

snmp-server enable traps vrrp

snmp-server enable traps ds1

snmp-server enable traps tty

snmp-server enable traps eigrp

snmp-server enable traps casa

snmp-server enable traps cnpd

snmp-server enable traps pw vc

snmp-server enable traps syslog

snmp-server enable traps isdn call-information

snmp-server enable traps isdn layer2

snmp-server enable traps isdn chan-not-avail

snmp-server enable traps isdn ietf

snmp-server enable traps ds3

snmp-server enable traps atm subif

snmp-server enable traps channel

snmp-server enable traps ima

snmp-server enable traps srp

snmp-server enable traps flash insertion removal

snmp-server enable traps hsrp

snmp-server enable traps config

snmp-server enable traps entity

snmp-server enable traps fru-ctrl

snmp-server enable traps cpu threshold

snmp-server enable traps config-copy

snmp-server enable traps envmon

snmp-server enable traps aaa_server

snmp-server enable traps agw

snmp-server enable traps bgp

snmp-server enable traps ospf state-change

snmp-server enable traps ospf errors

snmp-server enable traps ospf retransmit

snmp-server enable traps ospf lsa

snmp-server enable traps ospf cisco-specific state-change nssa-trans-change

snmp-server enable traps ospf cisco-specific state-change shamlink interface-old

snmp-server enable traps ospf cisco-specific state-change shamlink neighbor

snmp-server enable traps ospf cisco-specific errors

snmp-server enable traps ospf cisco-specific retransmit

snmp-server enable traps ospf cisco-specific lsa

snmp-server enable traps pim neighbor-change rp-mapping-change invalid-pim-message

snmp-server enable traps ipmulticast

snmp-server enable traps mvpn

snmp-server enable traps msdp

snmp-server enable traps rsvp

snmp-server enable traps frame-relay

snmp-server enable traps frame-relay subif

snmp-server enable traps ipsla

snmp-server enable traps stun

snmp-server enable traps dlsw

snmp-server enable traps bstun

snmp-server enable traps pppoe

snmp-server enable traps l2tun session

snmp-server enable traps l2tun pseudowire status

snmp-server enable traps ipmobile

snmp-server enable traps frame-relay multilink bundle-mismatch

snmp-server enable traps dsp card-status

snmp-server enable traps dsp oper-state

snmp-server enable traps event-manager

snmp-server enable traps alarms informational

snmp-server host 171.71.129.34 public

Mobile to Mobile Traffic Steering

In releases prior to BWG IOS Release 12.4(15)XL3, switching of peer-to-peer traffic only occured locally on the BWG. This feature enables the BWG to force all upstream traffic to the configured next hop address.

You can configure this feature through CLI as well as from AAA, and the name of the attribute is "uplink_nexthop" (a CISCO AVpair attribute). This is per-subscriber provisioning in AAA. Unlike many other AAA-based features, the BWG can dynamically make full use of the uplink_next hop from AAA during re-authentication as well. The "uplink_nexthop" attribute downloaded from AAA takes precedence over the configured "uplink nexthop" in the CLI.

Configuring Mobile to Mobile Traffic Steering

To configure the BWG to force all upstream traffic to the configured next hop address, perform the following tasks:


	Command	Purpose
Step 1	router(config)#wimax agw user group-list wimax router(config-gw-ugl)# user-group domain cisco.com router(config-gw-ug)#ip redirect ? traffic User group IP redirect traffic configuration commands router(config-gw-ug)#ip redirect traffic ? all Redirect all traffic router(config-gw-ug)#ip redirect traffic all ? A.B.C.D Redirect IP address router(config-gw-ug)#ip redirect traffic all 10.1.1.5	Enables the BWG to force all the upstream traffic to the configured next hop address .

Here is a sample configuration:

wimax agw user group-list wimax

 user-group domain cisco.com

  sla profile-name silver

  ip redirect traffic all 10.1.1.5

  ip static-allowed

CAR/AAA Configuration

CAR can be configured multiple ways to enable it to send attributes; one of the ways is to write an outgoing TCL script. This script is executed after basic authentication is performed. The CAR configuration is out of scope of this document, however a sample outgoing script is provided here for convenience.

Sample Outgoing Script on CAR

proc tAddBlaTS {request response environ} {

 if {[string compare [$environ get Response-Type] Access-Accept] == 0} {

    $response trace 5 "Tcl tAddAttrSLA entry point"

    $response put Class "class-wimax-changed"

    $response put WiMAX-AAA-Session-ID "A0123"

    $response put Termination-Action "RADIUS-Request"

    $response put Cisco-AVPair "user-realm=cisco.com"

    $response put Cisco-AVPair "sla-profile-name= platinum gold silver" APPEND

    $response put Cisco-AVPair "cpe-settings=7" APPEND

    $response put Cisco-AVPair "uplink_nexthop=10.10.10.24" APPEND'

    $response put Cisco-AVPair "vlan-id=12" APPEND

    $response put Cisco-AVPair "static-ip-allowed=1" APPEND

    $response put Framed-Route "5.5.0.0/16"

MIB Support

The BWG supports a Management Information Base (MIB) that describes objects that enable users and network management to remotely monitor the BWG using SNMP commands. The BWG supports two separate MIBs:

One contains global system information and parameters, base-station information, subscriber, flow, traffic and trap notification information.

The second contains information about the R6 signaling protocol information used between the base-station and the BWG. This includes overall gateway R6 information, and information per base-station.

The BWG MIB variables are not synchronized across a fail-over. Many MIB variables can be recreated on the standby from the synchronized state data. The NMS attempts to handle such a situation, and any inconsistencies in MIB data that result from this approach. The existing RF/CF MIB is also available.

Note The R6 MIB is not supported in the initial release of the BWG on the Cisco 7301 router platform.

Verifying MIB Support

To display various MIB parameters, perform the following tasks:


	Command	Purpose
Step 1	router# show wimax agw	Displays various system parameters, including BWG software version, number of base stations allowed, number of subscribers allowed, and others.
Step 2	router# show wimax agw stat internal	Displays BWG internal statistics.
Step 3	router# show wimax agw stat dhcp	Displays BWG DHCP statistics.
Step 4	router# show wimax agw stat	Displays BWG statistics.
Step 5	router# show wimax agw user-group	Displays BWG user group statistics.
Step 6	router# show wimax agw path	Displays BWG path statistics.

Configuration Examples

Here is sample output for the show wimax agw command:

router# show wimax agw

Access network gateway version 0.1, service is enabled

 AGW listening on UDP control port 2231

 Maximum Number of base station 500 allowed

 Maximum Number of subscriber 20000 allowed

  Number of signalling paths created 0

  Number of brearer paths created 0

  Number of subscribers connected 0

  Number of sessions created 0

  Number of flows created 0

  Traffic Sent 0 packets, 0 bytes

  Traffic Rcvd 0 packets, 0 bytes

  Number of framed routes

  Number of subscribers using the framed routes

  Current number of user auto-provisioned sessions

  The traffic is split for IP CS and ETH CS.

Here is sample output for the show wimax agw user-group command:

router# show wimax agw user-group

AGW User-Group-List

There are 3 user-groups configured in list wimax

User group domain name any

 User-Group overwritten Counter 0

 Service mode operational

 Sessions 0 associated

 IP-GRE Traffic Sent 0 packets, 0 bytes

 IP-GRE Traffic Received 0 packets, 0 bytes

 Eth-GRE Traffic Sent 0 packets, 0 bytes

 Eth-GRE Traffic Received 0 packets, 0 bytes

 Ingress Address filtering 0 packets, 0 bytes

 Traffic Received redirected 0 packets, 0 bytes

User group domain name cisco

 Service mode operational

 Sessions 0 associated

 Traffic Sent 0 packets, 0 bytes

 Traffic Received 0 packets, 0 bytes

 Ingress Address filtering 0 packets, 0 bytes

User group domain name unauthenticated

 Service mode operational

 Sessions 0 associated

 Traffic Sent 0 packets, 0 bytes

 Traffic Received 0 packets, 0 bytes

 Ingress Address filtering 0 packets, 0 bytes

router#show wimax agw user-group brief ?

Name            Sessions  Pkts-Tx   Bytes-Tx  Pkts-Rx   Bytes-Rx  VRF

any             0         0         0         0         0

cisco           0         0         0         0         0

unauthenticated 0         0         0         0         0

router#show wimax agw user-group any ?

  brief  Brief output

  |      Output modifiers

  <cr>

router#show wimax agw user-group any

User group domain name any

--------------------------------------

 Service mode operational

 Sessions 0 associated

 Traffic Sent 0 packets, 0 bytes

 Traffic Recevied 0 packets, 0 bytes

 Ingress Address filtering 0 packets, 0 bytes

router#show wimax agw user-group any brief

Name            Sessions  Pkts-Tx   Bytes-Tx  Pkts-Rx   Bytes-Rx  VRF

any             0         0         0         0         0

router#show wimax agw user-group name ?

  WORD  Enter User-group Name

router#show wimax agw user-group name cisco ?

  brief  Brief output

  |      Output modifiers

  <cr>

router#show wimax agw user-group name cisco

User group domain name cisco

--------------------------------------

 Service mode operational

 Sessions 0 associated

 Traffic Sent 0 packets, 0 bytes

 Traffic Recevied 0 packets, 0 bytes

 Ingress Address filtering 0 packets, 0 bytes

router#show wimax agw user-group name cisco brief ?

  |  Output modifiers

  <cr>

router#show wimax agw user-group name cisco brief

Name            Sessions  Pkts-Tx   Bytes-Tx  Pkts-Rx   Bytes-Rx  VRF

cisco 0         0         0         0         0

router#show wimax agw user-group unauthenticated ?

  brief  Brief output

  |      Output modifiers

  <cr>

router#show wimax agw user-group unauthenticated

User group domain name unauthenticated

--------------------------------------

 Service mode operational

 Sessions 0 associated

 Traffic Sent 0 packets, 0 bytes

 Traffic Recevied 0 packets, 0 bytes

 Ingress Address filtering 0 packets, 0 bytes

asn#sh wimax agw user-group unauthenticated b

asn#sh wimax agw user-group unauthenticated brief ?

  |  Output modifiers

  <cr>

router#show wimax agw user-group unauthenticated brief

Name            Sessions  Pkts-Tx   Bytes-Tx  Pkts-Rx   Bytes-Rx  VRF

unauthenticated    0         0         0         0           0

Here is sample output for the show wimax agw statistics command:

router# show wimax agw statistics

AGW Statistics

Message function type Undefined(0/0x0)

Message function type Data Path(3/0x3)

  Message type Deregistration Request(4/0x4)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Deregistration Response(5/0x5)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Deregistration Ack(6/0x6)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Registration Request(12/0xC)

   Number of messages sent 0

   Number of messages received 0

   Number of messages resent 0

  Message type Registration Response(13/0xD)

   Number of messages sent 0

   Number of messages received 0

...

Here is sample output for the show wimax agw statistics dhcp-relay command:

router# show wimax agw statistics dhcp-relay

AGW DHCP Statistics

   Tx to DHCP server Discover 0, Request 0

   Tx to DHCP server Release 0, Decline 0

   Tx to DHCP server Inform 0

   Rx from DHCP server Offer 0, Ack 0

   Rx from DHCP server Nak 0, Unknown 0

This output gives the statistics of DHCP messages that are relayed through the BWG. If the BWG happened to initiate any DHCP messages, these counters are not incremented.

Here is sample output for the show wimax agw statistics internal command:

Router# show wimax agw statistics internal

Last clearing of "show wimax agw statistics internal" counters 3d23h

 Signalling plane related statistics

  Signal packets processed messages 483

  Signal packets has pending messages 0

  Signal packets requeued messages 0

  Signal packets dropped too many pending messages 0

  Signal packets dropped service disabled 0

  Signal packets dropped service not ready 0

  Signal packets dropped no encapsulation interface 0

  Signal packets dropped CAC denied request 0

  Signal packets disposed by agw 0

 Data plane related statistics

  Data packets not ours encapsulation 0

  Data packets not ours encapsulation address 0

  Data packets not ours service disabled 0

  Data packets not ours invalid protocol type 0

  Data packets dropped invalid ip len 0

  Data packets dropped absent key data 0

  Data packets dropped flow not found 21

  Data packets dropped flow path not found 0

  Data packets dropped flow path invalid src address 0

  Data packets dropped session not found 0

  Data packets dropped subscriber not found 0

  Data packets dropped checksum error 0

  Data packets dropped ingress filtering 0

  Data packets dropped sequence number mismatch 0

  Data packets dropped invalid redirect address 0

  Data packets dropped throttling of punts from cef to process 0

  Data packets dropped gateway learning from upstream data packets 0

  Data packets dropped non-ARP and non-DHCP L2 multicast/broadcast data packets 0

  Data packets punted fragmented 0

  Data packets punted from cef path to process path 0

 Other related statistics

  Number of N/w behind MS in usrgrp enabled 0

  Total subscriber created  41

  Total subscriber deleted 45

  Total session created  41

  Total session deleted 45

  Total flow created  4

  Total flow deleted 7

  Total host created  0

  Total host deleted 0

  Total signalling path created  3

  Total signalling path deleted 3

  Total data path created  2

  Total data path deleted 2

  Number of hosts rejected 0

  Number of packets dropped due to Static IP Host not allowed 0

  Number of static hosts aged out 0

  Total sessions rejected due to unapproved BS 0

 Configuration related statistics

  Service flow profile not found 0

  QoS profile not found 0

  Classifier profile not found 0

  Sla profile not found 0

 Handoff related statistics

  Total handoffs succeeded 0

  Total handoff failed 0

  Total cmac key update succeeded 0

  Total cmac key update failed 0

  Total security key exchange succeeded 0

  Total security key exchange failed 0

 Miscellaneous statistics

  Maximum Subscriber exceeded 0

  Maximum BS exceeded 0

MIB Enhancements for BWG Release 1.1

The BWG Management Information Base (MIB) is updated to add Ethernet CS related counters of packets/bytes sent/received. The following MIB objects have been updated in BWG Release 1.1:

•Includes the new EthCS related pkt/bytes sent/receive variables.

•Includes a description of packets/bytes sent/receive counters that were modified.

For example, "The total number of Data Packets received" has been modified to "The total number of IP Data Packets received"

ASN GW Global Statistics

•The total number of IP Data Packets received

•The total number of IP Data Packets Sent

•The total number of IP Data bytes received

•The total number of IP Data bytes sent

•The total number of Ethernet CS Data Packets received

•The total number of Ethernet CS Data Packets Sent

•The total number of Ethernet CS Data bytes received

•The total number of Ethernet CS Data bytes sent

•Total number of hosts rejected

•Total number of static hosts aged out

The MIB also includes new objects for statistics related to ARP (total number of ARP requests received, total number of ARP replies sent, total number of ARP packets dropped), rejected host, and aged out static hosts.

GRE Keying

A GRE key is allocated per service flow in each direction. The GRE keys are exchanged using the RR-Request used to create the Data Path bearer. The GRE keys that correspond to the BWG are allocated by the BWG and sent to the BS during creation of the service flow using the RR-Request. Similarly, the GRE key values corresponding to the BS are allocated by the BS and sent to the BWG using the RR-Response message.

During Inter-BS mobility, new keys are allocated by the Base-station. The BWG keeps the same GRE keys.

The BWG allocates the GRE keys such that the values are not assigned immediately upon release.

VRF Support

A user-group can be configured with virtual route forwarding (VRF) support. This allows you to create an internal VRF entity to connect all traffic to/from the specific user-group.

QoS Support

QoS Support refers to both airlink QoS as well as mapping on the network. The ASNGW is responsible for sending down the qos parameters to the Base-station for creating appropriate service flows.

•Certain hosts can be given additional quality of service parameters

•A new R6 bearer (service flow) may be created corresponding to the hosts IP address. Multiple host can use this service flow

•The mapping of the host to the new R6 service flow is created, and communicated to the BS/MS via the RR-Request.

DSCP Marking Per Service Flow

Each service flow is mapped uniquely to a Diffserv Code Point (DSCP). This DSCP value is used to mark the outer IP header for downstream packets by the BWG, and by the BS for upstream packets.

The inner IP header for upstream and downstream packets is set by the BWG as per the mapping for the service flow, unless explicitly disabled by a CLI.

ACLs

ACLs are supported, and can be configured at a per-user group basis. This applies to all users that connect to the same user-group.

Source IP Address Validation

For all uplink packets, the allocated IP address for the corresponding MS or service flow is validated. If a mismatch is found, those packets are discarded.

To configure this feature, use the security subscriber address-filtering ingress command in gateway user group submode.

Support of Split Control and Data End Points for BS

The BS may have different end point IP addresses for the control and the data plane. Depending on the availability of the Data Path End Point ID TLV (sent in path registration response message from the BS for the flow), the BWG can create the GRE path taking the ipv4 from the available TLV.

If the specified TLV is not present, the control plane end point address is used as the remote data end point to create GRE path.

Bearer Accounting

Bearer volume counts are maintained for all service flows. These include the input and output packets and octet counts.

Restrictions

The following restriction apply in Cisco BWG Release 1.0 and above:

•To avoid issues with high CPU usage, we recommend the following configurations:

–To reduce the CPU usage during bootup, disable logging to the console terminal by configuring the no logging console global configuration command.

–To ensure that the HSRP interface does not declare itself active until it is ready to process a peers Hello packets, configure the delay period before the initialization of HSRP groups with the standby delay minimum 100 reload 100 interface configuration command under the HRSP interface.

–To minimize issues with high CPU usage for additional reasons, such as periods of high PPP PDP processing (creating and deleting), disable the notification of interface data link status changes on all virtual template interfaces of the BWG using the no logging event link-status interface configuration command.

interface Virtual-Template1

description ASNGW-VT

ip unnumbered Loopback0

encapsulation agw

no logging event link-status

access-point-list wimax

end

Features Not Supported

The following features are not supported in this release:

•Configuration synchronization: BWG relies on manual configurations to ensure identical feature configuration on the active and standby.

•In-Service-Software-Upgrade (ISSU): Upgrading from the immediate lower software version to a higher version is supported.

Bias-Free Language

Results

Chapter: Configuring the Cisco Broadband Wireless Gateway

Configuring the Cisco Broadband Wireless Gateway

Ethernet Convergence Sublayer (CS)

Ethernet Convergence Sublayer (CS)—R6 Control Only

Configuring R6 Control Only

Ethernet CS—Data and Control Both on R6

VLAN to VRF Mapping for L2-L3 Bridging

Packet Fragmentation Handling

DHCP Option 82 Enhancement

DSCP Calculation/Marking/Signaling

Ethernet Frame Support

Ethernet VLAN Support

Ethernet FCS (CRC)

Limitations

CPE Management

AAA Access for Unauthenticated Subscriber

New AAA Attributes

Configuring the SLA Profile

Multiple SLA Profile Support Per Subscriber

User Auto-Provisioning

Support for MS/Host with Statically Assigned IP

IP CS

Ethernet CS

ARP Request from Host

Uplink Packet from Host

Limitations

Other Enhancements

R6 Protocol Enhancement

R6 Attachment Request

R6 Attachment Response

R6 Data Path Registration Request

R6 Data Path Registration Response

Other R6 Changes

EAP Authentication

Network Admission of an Authenticated User

Support of Un-Authenticated User

Configuring AAA to Enable PAP Authentication on BWG

AAA Access for CPE Using PAP Authentication

Proxy Realm for CPE Using PAP Authentication

Auto-Provisioning for Unauthenticated CPE Using PAP Authentication

Configuring Authentication

Configuring AAA for Accounting Types

Configuring Authorization

Configuring Authentication

RADIUS Server

Configuring User Groups

Verifying the Configuration

Configuration Examples

Security Key Exchange

IP Address Allocation Using DHCP

Configuring IP Address Allocation

Multiple Host Support

Support of Multiple Hosts Behind a SS

DHCP Option 82

DHCP Option 82 Enhancement in Release 1.1

Service Flow Creation and Management

Service Flows

Multiple Service Flow Creation

Configuring BWG Service

Sample Configuration

Verifying the Configuration

Mapping of Service Flows to DiffServ Classes

Marking of Packets Corresponding to Service Flows

Configuring Service Flows on the BWG

Configuration Example

Configuring Service Flow Packet Classification

Configuration Example

QoS Support

Configuring QoS

Configuration Example

Verifying the Configuration

User Group Management

Sample Configuration

Idle Timer Support

Session Timer Support

Mobile Subscriber Station De-Registration

AAA Accounting Start-Stop-Interim