Access Node Control Protocol

First Published: June 25, 2009
Last Updated: June 25, 2009

The Access Node Control Protocol (ANCP) feature enhances communication between Digital Subscriber Line Access Multiplexers (DSLAMs) and a broadband remote access server (BRAS), enabling the exchange of events, actions, and information requests between the multiplexer end and the server end. As a result, either end can implement appropriate actions.

Finding Feature Information

For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Access Node Control Protocol" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for Access Node Control Protocol

•Restrictions for Access Node Control Protocol

•Information About Access Node Control Protocol

•How to Configure Access Node Control Protocol

•Configuration Examples for Access Node Control Protocol

•Additional References

•Feature Information for Access Node Control Protocol

Prerequisites for Access Node Control Protocol

To run ANCP over Transmission Control Protocol (TCP), IP must be enabled on broadband remote access servers (BRAS). Interactions from RADIUS to the BRAS are not required for ANCP and are dependent on the RADIUS server.

For information about release and platform support, see the "Feature Information for Access Node Control Protocol" section.

Restrictions for Access Node Control Protocol

Cisco IOS XE Release 2.4 supports interactions with the RADIUS server from the broadband remote access server (BRAS). Interactions from RADIUS to the BRAS are not required for ANCP and are dependent on the RADIUS server.

Information About Access Node Control Protocol

ANCP is used to aggregate traffic from multiple subscribers and deliver information for any application, while remaining independent from the application. ANCP is currently used in the application between DSLAMs and the broadband remote access server in a digital subscriber line (DSL) broadband environment.

The ANCP feature enables close communication between DSL aggregation multiplexers (DSLAMs) and network edge devices. Using ANCP between DSLAMs and a BRAS enables exchange of events, actions, and information requests so that the appropriate actions occur at the DSLAM and BRAS.

The ANCP architecture supports the following uses of ANCP:

•Rate Adaptive Mode

•Noninteractive Operation, Administration, and Maintenance

•Interactive OAM

•General Switch Management Protocol and ANCP

Rate Adaptive Mode

Rate adaptive mode helps to maximize the line bit rate for a given line, and the rate is dependent on the quality of the signal achieved on the line. Rate adaptive mode conveys DSL modem line rate from a DSLAM to a broadband remote access server.

A BRAS running ANCP listens for TCP requests from its ANCP neighbors (DSLAMs).

•After a TCP session is established—ANCP begins exchanging messages to establish adjacency between the BRAS and its neighbors.

•After adjacency is established—ANCP event messages can be sent from the DSLAM to the BRAS.

Rate adaptive DSL uses signal quality to adjust line speeds. A BRAS typically sets the subscriber interfaces to the maximum bandwidth agreed to in the service license agreement (SLA).

When customer premises equipment (CPE) is synchronized to a data rate that is lower than the line speed, cell or packet loss occurs on the DSLAM. To prevent this, the DSLAM can use ANCP to notify the BRAS of newly adjusted circuit rates.

When a customer-facing port:

•Activates — The DSLAM sends a Port Up message to the BRAS. The appropriate quality of service (QoS) takes effect in accordance with the ANCP-delivered information.

•Deactivates — The DSLAM sends a Port Down message to the BRAS. ANCP reports the DSL state sent by the DSLAM, which is typically Silent or Idle. If the broadband remote access server receives another Port Up message, the subscriber sessions either time out or are renewed with a new shaping rate. The shaping rate on the interface does not change until the router receives a new Port Up message.

RADIUS Interaction

Interactions between the broadband remote access server and the RADIUS server are from the router to RADIUS.

The BRAS sends the following attributes and attribute-value pairs (AVPs) to the RADIUS server:

ANCP Line Rates
Upstream Data Rate
Downstream Data Rate
Output Policy Name

VSA 39

Attribute 197, Ascend-Data-Rate

Attribute 255, Ascend-Xmit-Rate

Attribute 77, Connect-Speed-Info

Attribute Type 38, Rx Connect Speed AVP

Attribute Type 24, Tx Connect Speed AVP


The BRAS uses Point-to-Point Protocol (PPPoE) to interact with the authentication, authorization, and accounting (AAA) module. RADIUS processes the information and then takes appropriate action.

Port Mapping

Port mapping associates customer premises equipment (CPE) clients of a DSLAM with VLAN subinterfaces on the BRAS. The VLANs include 802.1Q or queue-in-queue (Q-in-Q) hierarchical VLANs. Port mapping is configured in global configuration mode on the BRAS by grouping CPE client IDs with a specific DSLAM neighbor.

There are two methods you can use to map ports: configure all VLAN subinterfaces first, and the ANCP neighbor mappings next. Or, you can configure the mappings directly under the interface.

For example, the following commands configure port mapping for Q-in-Q VLAN subinterfaces: 

ancp neighbor name dslam-name id dslam-id

dot1q outer-vlanid second-dot1q inner-vlanid [interface type number] client-id 
"client-id"

or 

ancp neighbor name dslam-name id dslam-id

dot1q outer-vlanid client-id "client-id"

The client-id is a unique access-loop-circuit-id that the DSLAM sends to the BRAS for each unique port. The DSLAM sends this ID in the ANCP Port Up event message. The access-loop-circuit-id uses a defined format consisting of an access node identifier and digital subscriber line (DSL) information as mentioned below:

ATM/DSL

"access-node-identifier atm slot/module/port.subinterface:vpi.vci"

Ethernet/DSL

"access-node-identifier ethernet slot/module/port.subinterface[:vlan-id]"

The BRAS sets the default state as Down, on all ports of the router, until the DSLAM sends a Port Up message.

Noninteractive Operation, Administration, and Maintenance

ANCP provides an out-of-band control channel for performing noninteractive operation, administration, and maintenance (OAM) operations from the broadband remote access server. This channel enables router operators to view the ANCP port state of specific DSLAM ports. ANCP port state information is stored in the ANCP dynamic database on the BRAS.

Interactive OAM

The Interactive OAM and Scaling Improvements feature adds on-demand ping capability to ANCP for operations and troubleshooting.

Note This feature is enabled by default and requires no configuration.

General Switch Management Protocol and ANCP

ANCP is an extension of the General Switch Management Protocol (GSMP). GSMP defines a master-slave neighbor relationship in which the master initiates a connection to a slave. In ANCP, this master-slave relationship is reversed—the BRAS (master) listens and accepts incoming ANCP connections from the DSLAM (slave). The DSLAM uses event messages to communicate asynchronous events to the BRAS, such as topology changes and Port Down or Port Up events.

GSMP connectivity between the BRAS and the DSLAM occurs over TCP/IP (RFC 3293). The DSLAM initiates the connection to the router and the router accepts the connection if the appropriate interface is ANCP enabled.

The GSMP Adjacency Protocol establishes GSMP neighbor relationships.

1. During the adjacency-building:

a. The DSLAM and router negotiate their capabilities and determine the synchronization state between the two ends.

b. GSMP detects whether the router and the DSLAM have retained a local information database state in case of a transport failure, or whether both devices require a state update.

c. If GSMP determines that it must resynchronize the adjacency, it restarts the adjacency synchronization process, which includes the capability negotiation defined in the ANCP extension draft available at:

http://tools.ietf.org/id/draft-wadhwa-gsmp-l2control-configuration-02.txt

2. In an ANCP, if a neighbor (neighbor1) contains capabilities that its neighbor (neighbor2) does not support, neighbor1 turns off the capabilities and recommunicates the packets to neighbor2 with the same set of capabilities as neighbor2.

3. After both the neighbors agree to the same set of capabilities, adjacency is established.

How to Configure Access Node Control Protocol

To configure ANCP, perform the following global or interface configuration tasks:

•Enabling ANCP on an Ethernet Interface

•Enabling ANCP on an ATM Interface

•Mapping DSLAM Ports to VLAN Interfaces on Broadband Remote Access Servers

•Mapping DSLAM Ports to PVC Interfaces on Broadband Remote Access Servers

Enabling ANCP on an Ethernet Interface

Use the following procedure to enable ANCP on an Ethernet interface.

SUMMARY STEPS

1. enable

2. configure terminal

3. ancp adjacency timer interval

4. interface type number

5. ip address address mask

6. ancp enable

7. interface type number.subinterface

8. encapsulation dot1q vlanid [second-dot1q second-vlanid]

9. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ancp adjacency timer interval

Example:

Router(config)# ancp adjacency timer 100

Sets the ANCP adjacency timer interval, which specifies the amount of time to wait before sending an ANCP hello packet to the DSLAM.

Step 4 

interface type number

Example:

Router(config)# interface FastEthernet1/0/0

Enters interface configuration mode to define an interface.

Step 5 

ip address address mask

Example:

Router(config-if)# ip address 10.16.1.2 255.255.0.0

Assigns an IP address and subnet mask to the interface.

Step 6 

ancp enable

Example:

Router(config-if)# ancp enable

Enables ANCP on the interface where IP is configured.

Step 7 

interface type number.subinterface

Example:

Router(config-if)# interface FastEthernet1/0/0.1

Enters subinterface configuration mode to define a subinterface.

Step 8 

encapsulation dot1q vlanid [second-dot1q second-vlanid]

Example:

Router(config-subif)# encapsulation dot1q 100 second-dot1q 200

Enables dot1q VLAN encapsulation on the subinterface for a single-queue 802.1Q VLAN or for Q-in-Q hierarchical VLANs.

Step 9 

exit

Example:

Router(config-subif)# exit

Exits subinterface configuration mode.

Enabling ANCP on an ATM Interface

The ancp enable command should be configured only for the control VCs on which the ANCP message is sent from the DSLAM. Use the following procedure to enable ANCP on ATM interfaces.

SUMMARY STEPS

1. enable

2. configure terminal

3. ancp adjacency timer interval

4. interface atm slot/subslot/port.subinterface

5. ip address ip-address mask

6. pvc vpi/vci

7. ancp enable

8. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ancp adjacency timer interval

Example:

Router(config)# ancp adjacency timer 100

Sets the ANCP adjacency timer interval, which specifies the amount of time to wait before sending an ANCP hello packet to the DSLAM.

Step 4 

interface atm slot/subslot/port.subinterface

Example:

Router(config)# interface atm 2/0/1.1

Enters subinterface configuration mode to define a subinterface.

Step 5 

ip address ip-address mask

Example:

Router(config-subif)# ip address 10.16.1.2 255.255.0.0

Assigns an IP address and subnet mask to the subinterface.

Step 6 

pvc vpi/vci

Example:

Router(config-subif)# pvc 2/100

Enters ATM virtual circuit configuration mode to enable an ANCP connection over ATM PVC.

Step 7 

ancp enable

Example:

Router(config-if-atm-vc)# ancp enable

Enables ANCP on the interface where IP is configured.

Step 8 

exit

Example:

Router(config-if-atm-vc)# exit

Exits ATM virtual circuit configuration mode.

Mapping DSLAM Ports to VLAN Interfaces on Broadband Remote Access Servers

Use the following procedure to map DSLAM ports to VLAN interfaces on the BRAS.

SUMMARY STEPS

1. enable

2. configure terminal

3. ancp atm shaper percent-factor factor

4. interface type number.subinterface

5. encapsulation dot1q vlan-id

6. ancp neighbor name dslam-name [id dslam-id] client-id client-id

7. exit

DETAILED STEPS
 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ancp atm shaper percent-factor factor

Example:

Router(config)# ancp shaper percent-factor 95

Enables ANCP cell tax accounting for ATM U-interface connections

Step 4 

interface type number.subinterface

Example:

Router(config)# interface FastEthernet0/0.1

Enters interface configuration mode for the specified subinterface.

Step 5 

encapsulation dot1q vlan-id

Example:

Router(config-subif)# encapsulation dot1q 411

Enables IEEE 802.1Q encapsulation of traffic on a specified VLAN.

Step 6 

ancp neighbor name dslam-name [id dslam-id] client-id client-id

Example:

Router(config-subif)# ancp neighbor name dslam1 id 1.2.3.4 client-id "1.2.3.4. eth 0/0.1"

Specifies the ANCP access DSLAM to which VLAN subinterfaces are mapped.

Step 7 

exit

Example:

Router(config-subif)# exit

Exits subinterface configuration mode.

Mapping DSLAM Ports to PVC Interfaces on Broadband Remote Access Servers

The ancp neighbor name command is available under pvc and pvc-in-range command modes. This command creates a one-to-one mapping between a PVC and a DSLAM port. Use the following procedure to map DSLAM ports to PVC interfaces on the BRAS.

SUMMARY STEPS

1. enable

2. configure terminal

3. ancp atm shaper percent-factor factor

4. interface atm slot/subslot/port.subinterface

5. pvc vpi/vci
or
range pvc start-vpi/start-vci end-vpi/end-vci

6. pvc-in-range vpi/vci

7. ancp neighbor name dslam-name [id dslam-id] client-id client-id

8. end

DETAILED STEPS
 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ancp atm shaper percent-factor factor

Example:

Router(config)# ancp shaper percent-factor 95

Enables ANCP cell tax accounting for ATM U-interface connections.

Step 4 

interface atm slot/subslot/port.subinterface

Example:

Router(config)# interface atm 2/0/1.1

Enters interface configuration mode for the specified ATM subinterface.

Step 5 

pvc vpi/vci

or

range pvc start-vpi/start-vci end-vpi/end-vci

Example:

Router(config-subif)# pvc 1/101

or

Example:

Router(config-subif)# range pvc 9/100 9/102

Creates a one-to-one mapping between a PVC and DSLAM port and enters ATM virtual circuit configuration mode.

or

Defines a range of ATM PVCs and enters PVC range configuration mode.

•If a range of ATM PVCs are defined, use the pvc-in-range command to configure an individual PVC.

Step 6 

pvc-in-range vpi/vci

Example:

Router(config-if-atm-range-pvc)# pvc-in-range 9/100

(Optional) Configures an individual PVC within a range in PVC range configuration mode.

Step 7 

ancp neighbor name dslam-name [id dslam-id] client-id client-id

Example:

Router(config-if-atm-range-pvc)# ancp neighbor name dslam1 id 1.2.3.4 client-id "1.2.3.4. atm0/0.1"

Specifies the ANCP access DSLAM to which PVC subinterfaces are mapped.

•This command is available under PVC range and ATM virtual circuit configuration modes.

Step 8 

end

Example:

Router(config-if-atm-range-pvc)# end

Exits PVC range configuration mode.

Configuration Examples for Access Node Control Protocol

This section provides the following configuration examples:

•Enabling Access Node Control Protocol on Ethernet Interfaces: Example

•Enabling Access Node Control Protocol on ATM Interfaces: Example

•Mapping DSLAM Ports to VLAN Interfaces on the BRAS: Example

•Mapping DSLAM Ports to PVC Interfaces on the BRAS: Example

Enabling Access Node Control Protocol on Ethernet Interfaces: Example

The following example shows how to enable ANCP on Ethernet subinterface 2/0/1. 

interface GigabitEthernet 2/0/1

 ip address 192.168.64.16 255.255.255.0

 ancp enable

!

interface GigabitEthernet 2/0/1.1

 encapsulation dot1q 100 second-dot1q 200

!

ancp adjacency timer 100

Enabling Access Node Control Protocol on ATM Interfaces: Example

The following example shows how to enable ANCP on ATM subinterface 2/0/1.1. 

interface ATM2/0/0.1 point-to-point

 description ANCP Link to one DSLAM

 no ip mroute-cache

 ip address 192.168.0.2 255.255.255.252

 pvc 254/32

   protocol ip 192.168.0.1

   ancp enable

   no snmp trap link-status

Mapping DSLAM Ports to VLAN Interfaces on the BRAS: Example

The following example shows how to map the CPE client ports of a DSLAM to Q-in-Q VLAN subinterfaces on the BRAS. In the example, the DSLAM neighbor named dslam1 with an IP address of 192.68.10.5 has a CPE client port mapped to Q-in-Q VLANs 100 and 200 configured on Ethernet interface 1/0/0.2. Another CPE client port is mapped to Q-in-Q VLANs 100 and 100 configured on Ethernet interface 1/0/0.1. 

interface GigabitEthernet1/0/0.1

 encapsulation dot1q 100 second-dot1q 100 

 ancp neighbor name dslam1 id 192.168.10.5 client-id "192.168.10.5 ethernet1/0/0.2"

!

interface GigabitEthernet1/0/0.2

 encapsulation dot1q 100 second-dot1q 200

 ancp neighbor name dslam1 id 192.168.10.5 client-id "192.168.10.5 ethernet1/0/0.1"

!

ancp atm shaper percent-factor 95

!

The example shown above maps the ports directly at the subinterface level. You can also configure all VLAN subinterfaces first, and perform the mappings under ANCP neighbor next, as shown in the following example: 

interface GigabitEthernet1/0/0.1

 encapsulation dot1q 100 second-dot1q 100

!

interface GigabitEthernet1/0/0.2

 encapsulation dot1q 100 second-dot1q 200

!

ancp atm shaper percent-factor 95

!

ancp neighbor name dslam1 id 192.168.10.5

 dot1q 100 second-dot1q 100 interface GigabitEthernet1/0/0.1 client-id "192.168.10.5  
ethernet1/0/0.2"

!

ancp neighbor name dslam1 id 192.168.10.5

 dot1q 100 second-dot1q 200 interface GigabitEthernet1/0/0.2 client-id "192.168.10.5 
ethernet1/0/0.2"

Mapping DSLAM Ports to PVC Interfaces on the BRAS: Example

The ancp neighbor name command maps the CPE client ports of a DSLAM to PVC interfaces on the BRAS. This command can be configured either globally or under PVC/PVC-in-Range mode.

In PVC or PVC-in-Range Configuration Mode

In this example, the router interfaces with one DSLAM which has two ports or clients. 

interface ATM2/0/0.1 point-to-point

  description ANCP Link to one DSLAM

  no ip mroute-cache

  ip address 192.168.0.2 255.255.255.252      

  pvc 254/32

     protocol ip 192.168.0.1 255.255.255.252

     ancp neighbor name dslam1 id 192.168.10.5 client-id "dslam-port-x-identifier"

        no snmp trap link-status

      !

interface ATM1/0/0.1 multipoint

  description TDSL clients - default TDSL 1024

  class-int speed:ubr:1184:160:10

  range pvc 10/41 10/160

    service-policy input SET-PRECEDENCE-0

    service-policy output premium-plus:l2c:25088

    pvc-in-range 10/103

      description TDSL client 16 Mbps with ANCP

      class-vc speed:ubr:17696:1184:05

      ancp neighbor name dslam1 id 192.168.10.5 client-id "dslam-port-x-identifier"

       !

  range pvc 11/41 11/160

    service-policy input SET-PRECEDENCE-0

    service-policy output premium-plus:l2c:25088

    pvc-in-range 11/108

      description TDSL client 16 Mbps with ANCP

      class-vc speed:ubr:17696:1184:05

      ancp neighbor name dslam1 id 192.168.10.5 client-id "dslam-port-y-identifier"

        !

In Global Configuration Mode

When the ancp neighbor command is configured globally, the PVC information for the ATM interface must also be specified, as shown in the following example: 

interface ATM1/0/0.1 multipoint

 description TDSL clients - default TDSL 1024

 class-int speed:ubr:1184:160:10

 range pvc 10/41 10/160

   service-policy input SET-PRECEDENCE-0

   service-policy output premium-plus:l2c:25088

   pvc-in-range 10/103

     description TDSL client 16 Mbps with ANCP

     class-vc speed:ubr:17696:1184:05

!

 range pvc 11/41 11/160

   service-policy input SET-PRECEDENCE-0

   service-policy output premium-plus:l2c:25088

   pvc-in-range 11/108

     description TDSL client 16 Mbps with ANCP

     class-vc speed:ubr:17696:1184:05

!

ancp neighbor name dslam1 id 192.168.10.5

 atm 10/103 interface ATM1/0/0.1 client-id "dslam-port-x-identifier"

 atm 11/108 interface ATM1/0/0.1 client-id "dslam-port-y-identifier"

Additional References

The following sections provide references related to the Access Node Control Protocol feature.

Related Documents

Related Topic
Document Title

IEEE 802.1Q VLAN

Configuring Routing Between VLANs with IEEE 802.1Q Encapsulation

Queue-in-Queue VLAN Tags

IEEE 802.1Q-in-Q VLAN Tag Termination

ANCP Commands

Cisco IOS Access Node Control Protocol Command Reference


RFCs

RFC
Title

ANCP extension draft

GSMP Extensions for Access Node Control Mechanism, Internet draft

RFC 3292

General Switch Management Protocol (GSMP) V3

RFC 3293

General Switch Management Protocol (GSMP), Packet Encapsulations for Asynchronous Transfer Mode (ATM), Ethernet and Transmission Control Protocol (TCP)


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for Access Node Control Protocol

Table 1 lists the features in this module and provides links to specific configuration information.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.

Table 1 Feature Information for Access Node Control Protocol 

Feature Name
Releases
Feature Information

Access Node Control Protocol

Cisco IOS XE Release 2.4

In Cisco IOS XE Release 2.4, this feature was introduced on the Cisco ASR 1000.

The following sections provide information about this feature:

•Information About Access Node Control Protocol

•How to Configure Access Node Control Protocol

The following command was introduced: ancp vdsl ethernet shaper.

Interactive OAM and Scaling Improvements

Cisco IOS XE Release 2.4

The Interactive OAM and Scaling Improvements feature adds on demand ping capability to ANCP for operations and troubleshooting.

In Cisco IOS XE Release 2.4, this feature was introduced on the Cisco ASR 1000.

The following commands were introduced or modified: ping ancp, show ancp neighbor port, show ancp port, show ancp session, show ancp session adjacency, show ancp session event, and show ancp statistics.


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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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