Cisco IOS CMTS Cable Software Configuration Guide, Release 12.2SC - Transparent LAN Service over Cable [Cisco uBR10000 Series Universal Broadband Routers]

Table Of Contents

Transparent LAN Service over Cable

Contents

Prerequisites for Transparent LAN Service over Cable

Restrictions for Transparent LAN Service over Cable

Information About Transparent LAN Service over Cable

Feature Overview

Transparent LAN Service and Layer 2 Virtual Private Networks

ATM PVC Mapping

Overview

Details of ATM PVC Mapping

IEEE 802.1Q Mapping

Overview

Details of IEEE 802.1Q Mapping

Benefits

How to Configure the Transparent LAN Service over Cable Feature

Configuring Layer 2 Tunneling for ATM PVC Mapping

Enabling and Configuring Layer 2 Tunneling and ATM PVC Mapping

Creating the ATM Virtual Connections and Bridge Group

Restrictions

Configuring IEEE 802.1Q VLAN Mapping

Enabling and Configuring Layer 2 Tunneling for IEEE 802.1Q Mapping

Creating the IEEE 802.1Q VLAN Bridge Group

Configuration Examples for Transparent LAN Service over Cable

CMTS ATM PVC Mapping Configuration Example

ATM Bridge Aggregator Configuration Example

CMTS IEEE 802.1Q VLAN Mapping Configuration Example

IEEE 802.1Q Bridge Aggregator Configuration Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Transparent LAN Service over Cable

This document describes the Transparent LAN Service over Cable feature, which enhances existing Wide Area Network (WAN) support to provide more flexible Managed Access for multiple Internet service provider (ISP) support over a hybrid fiber-coaxial (HFC) cable network. This feature allows service providers to create a Layer 2 tunnel by mapping an upstream service identifier (SID) to an ATM permanent virtual connection (PVC) or to an IEEE 802.1Q Virtual Local Area Network (VLAN).

Feature Specifications for Transparent LAN Service over Cable

Feature History

Release

Modification

Release 12.2(11)BC3

This feature was introduced for Cisco uBR7100 series and Cisco uBR7246VXR universal broadband routers to support Layer 2 encapsulation over ATM networks.

Release 12.2(15)BC2

Support was added for IEEE 802.1Q Virtual Local Area Network (VLAN) tagging on the Cisco uBR7246VXR universal broadband router. Support was also added for identifying mappings with a customer name.

Release 12.3(9a)BC

Support was added for Transparent LAN Services (TLS) for the following Cisco CMTS platforms:

•IEEE 802.1Q on the Cisco uBR10012 router with Cisco uBR10012 PRE2 performance routing engine modules

•ATM on the Cisco uBR7246VXR router

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

This document includes the following major sections:

•Prerequisites for Transparent LAN Service over Cable, page 2

•Restrictions for Transparent LAN Service over Cable, page 2

•Information About Transparent LAN Service over Cable, page 3

•How to Configure the Transparent LAN Service over Cable Feature, page 7

•Configuration Examples for Transparent LAN Service over Cable, page 14

•Additional References, page 17

•Command Reference, page 19

Prerequisites for Transparent LAN Service over Cable

The Transparent LAN Service over Cable feature has the following prerequisites:

•Cisco uBR7100 series and Cisco uBR7246VXR routers must be running Cisco IOS Release 12.2(11)BC3 or later to support ATM PVC mapping. The routers must be running Cisco IOS Release 12.2(15)BC2 or later to support IEEE 802.1Q VLAN mapping.

•You must know the hardware (MAC) addresses of the cable modems that are to be mapped to ATM PVCs or IEEE 802.1Q VLANs.

•You must create a bridge group for each separate customer on the Layer 2 bridge aggregator, so that traffic from all of the Customer Premises Equipment (CPE) devices for the customer is grouped together into the same ATM or 802.1Q tunnel.

Restrictions for Transparent LAN Service over Cable

The Transparent LAN Service over Cable feature has the following restrictions and limitations:

•Configuring ATM L2VPN or 802.1q for a particular cable modem removes any previous cable modem configuration on the Cisco uBR7246VXR router. For example, if TLS with 802.1q is configured on the router for a particular cable modem, and then you configure ATM L2VPN for the same cable modem, the Cisco uBR7246VXR router supports the latter and removes the former with no additional warning or system messages.

•Cisco strongly recommends that TLS over Cable only be used when Baseline Privacy Interface (BPI) is enabled in the environment. If BPI is not enabled when using the TLS feature, traffic can flow between multiple virtual private networks (VPNs), and become vulnerable to denial-of-service attacks or snooping. Cisco also recommends that remote networks be isolated with a gateway or firewall router when BPI is not enabled.

Commencing in Cisco IOS release 12.3(13a)BC, and later releases, when the TLS feature is used with Layer 2 VPNs, the participating cable modems must have the Baseline Privacy Interface security feature (BPI) enabled. Otherwise, the Cisco CMTS drops such Layer 2 traffic in the upstream or downstream.

•The Transparent LAN Service over Cable is not supported on the Cisco uBR10012 universal broadband router when using the PRE-1 module.

•You cannot mix IEEE 802.1Q and ATM PVC mapping in the same bridge group. To use both types of mappings on the same Cisco CMTS, you must use separate bridge groups.

•Packets are mapped to their Layer 2 tunnel only on the basis of Layer 2 information (the cable modem's MAC address and primary SID). Layer 3 services, such as access lists, IP address source-verify, and IP QoS, are not supported as packets are sent through the tunnel.

•All traffic from a cable modem is mapped to the same Layer 2 tunnel. It is not possible to differentiate traffic from different customer premises equipment (CPE) devices behind the cable modem.

•CPE learning is not available when using the Transparent LAN Service over Cable feature. When a cable modem is mapped to a Layer 2 tunnel, the show interface cable modem command shows that the IP addresses for its CPE devices are "unavailable."

•DOCSIS QoS is supported across the Layer 2 tunnel only on the primary SID. Traffic using secondary services uses the same Layer 2 tunnel as the primary SID.

•The Spanning Tree Protocol (STP) cannot be used with devices (cable modems, their CPE devices, and the endpoint CPE devices) that are using this feature. In particular, Spanning Tree Protocol cannot be used between the VLAN bridge aggregator and the endpoint customer devices.

•The following restrictions apply to Layer 2 tunnels over an ATM interface:

–The virtual connections (VC) on the ATM interface must be configured to use ATM Adaptation Layer 5 (AAL5) IEEE 802.1a Subnetwork Access Point (SNAP) encapsulation. On Cisco routers, this means that each PVC endpoint must be configured for the proper encapsulation using the encapsulation aal5snap command.

–If a cable modem is being mapped to an ATM PVC, all of its CPE traffic is sent through the ATM tunnel through the ATM cloud, even if the ultimate destination is another cable modem on the same CMTS.

–Cable modems must have a one-to-one mapping with ATM PVCs, with each cable modem being mapped to its own ATM PVC. Cable modems cannot share a single PVC. Multiple PVCs from the same customer are aggregated at the ATM bridge aggregator into the same bridge group.

•The following restrictions apply to Layer 2 tunnels over an Ethernet IEEE 802.1Q VLAN interface:

–IEEE 802.1Q tunnels are supported only on Ethernet, Fast Ethernet, and Gigabit Ethernet interfaces.

–The Cisco CMTS router supports a maximum of 4095 VLAN IDs, but the switches acting as the bridge aggregator might support a lower number of VLAN IDs. If this is the case, the Cisco CMTS should be configured only for the maximum number of VLANs that are supported by the bridge aggregator switches.

Information About Transparent LAN Service over Cable

This section describes the following variations of the Transparent LAN Service over Cable feature:

•Feature Overview, page 4

•ATM PVC Mapping, page 4

•IEEE 802.1Q Mapping, page 5

•Benefits, page 7

Feature Overview

The Transparent LAN Service over Cable feature enables service providers to provide Layer 2 tunnels for traffic to and from cable modems. This allows customers to create their own virtual local area network (VLAN) using any number of cable modems in multiple sites.

On the Cisco CMTS, you map each cable modem (on the basis of its MAC address) to the appropriate VLAN. The CMTS then creates an internal database of this one-to-one mapping of cable modems to VLANs, and uses it to encapsulate packets for the appropriate VLAN.

The CMTS encapsulates the CPE traffic from mapped cable modems using one of the following methods:

•ATM PVC Mapping—The cable modem's MAC address is mapped to a PVC on a specific ATM interface, so that all traffic from the cable modem is sent over that particular PVC.

•IEEE 802.1Q Mapping—The cable modem's MAC address is mapped to an IEEE 802.1Q VLAN on a specific Ethernet interface, so that all traffic from the cable modem is tagged with the specified VLAN ID.

Traffic to and from this group of cable modems is bridged into a single logical network (the VLAN) by the bridge aggregator, creating a secure Virtual Private Network (VPN) for that particular group of cable modems. Traffic in one VLAN cannot be sent into another VLAN, unless specifically done so by an external router.

The switch acting as the Layer 2 Bridge Aggregator uses the ATM PVC or the VLAN tagging to forward the traffic to the appropriate destination. This frees up service providers from needing to know the addressing, routing, and topological details of the customer's network.

Transparent LAN Service and Layer 2 Virtual Private Networks

In addition, service providers can provide a Layer 2 VPN with only minimal configuration changes on the provider's routers. The service subscriber does not need to make any changes to their private network or cable modems, nor does the service provider have to provide any special DOCSIS configuration files to enable this feature.

Cisco IOS Release 12.3(13a)BC introduces the following changes or requirements for the TLS feature with Layer 2 VPNs:

•When the TLS feature is used with Layer 2 VPNs, the participating cable modems must have the Baseline Privacy Interface security feature (BPI) enabled. Otherwise, the Cisco CMTS drops such Layer 2 traffic in the upstream or downstream.

•Information about Customer Premises Equipment (CPE) does not display in the output of the show cable modem command.

ATM PVC Mapping

This section describes the mapping of cable modems to an ATM PVC, as it is available in the Transparent LAN Service over Cable feature:

•Overview, page 5

•Details of ATM PVC Mapping, page 5

Overview

The Transparent LAN Service over Cable feature enables service providers to provide Layer 2 tunnels over an existing ATM network. This allows customers to create their own virtual network using any number of cable modems that are located at multiple sites.

On the Cisco CMTS, you map each cable modem (on the basis of its MAC address) to a separate PVC on an ATM interface. The CMTS then creates an internal database of this one-to-one mapping of cable modems to PVCs, and uses it to determine which packets should be forwarded to the ATM network.

The CMTS encapsulates the CPE traffic from mapped cable modems using AAL5 SNAP encapsulation, as defined in RFC 1483, Multiprotocol Encapsulation over ATM Adaptation Layer 5. It then forwards those packets to the appropriate ATM interface and PVC.

Traffic to and from this group of cable modems is routed to a group of PVCs that are bridged into a single ATM network by the ATM bridge aggregator, creating a secure Virtual Private Network (VPN) for that particular group of cable modems.

Details of ATM PVC Mapping

To implement the Transparent LAN Service over Cable feature for ATM networks, a service provider must perform the following configuration steps:

1. Identify the cable modems and their MAC addresses that should be mapped to ATM PVCs.

2. Define one PVC (using AAL5 SNAP encapsulation) for each cable modem to be mapped. This must be done on both endpoints (the CMTS router and the ATM bridge aggregator).

3. Create a bridge group for each customer on the ATM bridge aggregator, and assign all of a customer's PVCs to the same bridge group, so that all of the mapped traffic for that customer is bridged into the same MAC domain on the ATM bridge aggregator.

4. Enable Layer 2 mapping on the CMTS, and then map each cable modem on that CMTS to the appropriate PVC.

After the Transparent LAN Service over Cable feature has been enabled and configured, the CMTS immediately begins mapping traffic between the associated cable modems and PVCs. For efficient mapping between the DOCSIS and ATM networks, the CMTS maintains an internal database that links SIDs to the PVCs. This ensures that all service flows from the cable modem are routed properly.

When the CMTS receives a packet on an upstream, it looks up the SID to see if it is mapped to a PVC. If so, and if the packet's source MAC address is not the cable modem's MAC address, the CMTS encapsulates the packet using an AAL5 SNAP header and forwards it to the appropriate PVC on the ATM interface. If the packet is not being mapped, or if the packet originated from the cable modem, the CMTS routes the packet as normal.

When the CMTS receives a packet from a PVC on the ATM interface, it looks up the PVC/PVI information to see if it is mapped to a SID. If so, the CMTS strips off the AAL5 SNAP header, adds a proper DOCSIS header, and transmits the packet on the appropriate downstream interface. If the packet's PVC is not being mapped, the CMTS continues processing the packet on the ATM network.

IEEE 802.1Q Mapping

This section describes the mapping of cable modems to an IEEE 802.1Q VLAN, as it is available in the Transparent LAN Service over Cable feature:

•Overview, page 6

•Details of IEEE 802.1Q Mapping, page 6

Overview

The Transparent LAN Service over Cable feature enables service providers to provide Layer 2 tunnels over an Ethernet network, using IEEE 802.1Q standard tags. This allows customers to create their own virtual network using any number of cable modems in different sites.

On the Cisco CMTS, you map each cable modem (on the basis of its MAC address) to the appropriate VLAN. The CMTS then creates an internal database of this one-to-one mapping of cable modems to VLANs, and uses it to encapsulate packets for the appropriate VLAN.

The CMTS encapsulates the CPE traffic from mapped cable modems using VLAN tags, as defined in IEEE 802.1Q-1993, IEEE Standards for Local and Metropolitan Area Networks: Virtual Bridged Local Area Networks. The switch acting as the Layer 2 Bridge Aggregator uses the VLAN tagging to forward the packets to the appropriate destination.

Traffic to and from this group of cable modems is bridged into a single logical network by the bridge aggregator, creating a secure Virtual Private Network (VPN) for that particular group of cable modems. Traffic in one VLAN cannot be sent into another VLAN, unless specifically done so by an external router.

Details of IEEE 802.1Q Mapping

To implement the Transparent LAN Service over Cable feature using IEEE 802.1Q VLANs, a service provider must perform the following configuration steps:

1. Identify the cable modems and their MAC addresses that should be mapped to the IEEE 802.1Q VLANs.

2. Create the required VLANs on the router that is acting as the bridge aggregator.

3. Enable Layer 2 mapping on the CMTS, and then map each cable modem on that CMTS to the appropriate VLAN.

After the Transparent LAN Service over Cable feature has been enabled and configured to use IEEE 802.1Q mappings, the CMTS immediately begins mapping traffic between the associated cable modems and VLANs. For efficient mapping, the CMTS maintains an internal database that links each cable modem's primary service flow ID (SFID) and service ID (SID) to the appropriate VLAN and Ethernet interface. This ensures that all service flows from the cable modem are routed properly.

When the CMTS receives a packet on an upstream, it looks up its SID to see if it is mapped to a VLAN. If so, and if the packet's source MAC address is not the cable modem's MAC address, the CMTS inserts the appropriate IEEE 802.1Q VLAN tag into the packet's header and forwards the packet to the appropriate Ethernet interface. If the packet is not being mapped, or if the packet originated from the cable modem, the CMTS routes the packet using the normal Layer 3 processes.

When the CMTS receives a packet from a WAN interface that is encapsulated with an IEEE 802.1Q VLAN tag, it looks up the packet's SID to see if it belongs to a cable modem being mapped. If so, the CMTS strips off the VLAN tag, adds the proper DOCSIS header, and transmits the packet on the appropriate downstream interface. If the packet is not being mapped, the CMTS continues with the normal Layer 3 processing.

Benefits

The Transparent LAN Service over Cable feature provides the following benefits to cable service providers and their partners and customers:

•Provides Layer 2 level mapping, which is transparent to Layer 3 protocols and services. This means that service providers do not need to know the details of their customers' network topologies, routing protocols, or IP addressing.

•Allows service providers to maximize the use of their existing ATM or Ethernet WAN networks. Multiple customers can be combined on the same outgoing interface, while still ensuring that each customer's network is kept private while it is transmitted over the tunnel.

•Provides a highly flexible and scalable solution for multiple customers. The service provider needs to create only one bridge group for each VPN, and then only one ATM PVC or VLAN mapping for each cable modem that should participate in that VPN tunnel.

•Customers retain full control over their private networks, while service providers retain full control over cable modems and the rest of the cable and ATM networks. Only the CPE traffic from the cable modems is mapped into the ATM tunnel, while traffic originating at the cable modem continues to be processed as normal by the service provider's network.

•Allows service providers to mix tunneled and nontunneled cable modems on the same DOCSIS cable network.

•Allows customers to create a single, secure virtual network with Ethernet Layer 2 connectivity for multiple sites.

•Allows multiple tunnels from different customers and endpoints to be aggregated into a single bridge, so as to maximize the use of bandwidth and other network resources.

•Supports the tunneling of multiple Layer 3, non-IP protocols, and not just IP Layer 3 services, as is the case with Layer 3 solutions, such as Multiprotocol Label Switching (MPLS) VPNs.

•All DOCSIS services, including BPI+ encryption and authentication, continue to be supported for all cable modems.

How to Configure the Transparent LAN Service over Cable Feature

This section describes the following tasks that are required to implement the Transparent LAN Service over Cable feature:

•Configuring Layer 2 Tunneling for ATM PVC Mapping, page 7

•Configuring IEEE 802.1Q VLAN Mapping, page 11

Configuring Layer 2 Tunneling for ATM PVC Mapping

This section describes how to enable Layer 2 mapping on the Cisco CMTS, and then to map particular cable modems to an ATM PVC.

•Enabling and Configuring Layer 2 Tunneling and ATM PVC Mapping, page 8

•Creating the ATM Virtual Connections and Bridge Group, page 9

Enabling and Configuring Layer 2 Tunneling and ATM PVC Mapping

This section describes how to enable Layer 2 mapping on the Cisco CMTS, and then to map particular cable modems to PVCs on an ATM interface.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable l2-vpn-service atm-vc

4. cable vc-map mac-address atm-interface vpi/vci [cust-name]

5. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable
Router#

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal
Router(config)#

Enters global configuration mode.

Step 3

cable l2-vpn-service atm-vc
Example:

Router(config)# cable l2-vpn-service atm-vc
Router(config)#

Enables Layer 2 tunneling for the Transparent LAN Service over Cable feature.

Step 4

cable vc-map mac-address atm-interface vpi/vci [cust-name]
Example:

Router(config)# cable vc-map 0000.0C04.0506 A3/0/0 1/1
Router(config)#

Maps the specified MAC address of a cable modem to the indicated PVC and ATM interface.

Note Repeat this command for each cable modem that is to be mapped to an ATM PVC.

Step 5

end
Example:

Router(config)# end
Router#

Exits global configuration mode and returns to privileged EXEC mode.

Creating the ATM Virtual Connections and Bridge Group

This section describes the minimum configuration needed to configure a Cisco router, which is acting as an ATM bridge aggregator, so that it can terminate the PVCs being used with the Transparent LAN Service over Cable feature.

Restrictions

Each bridge group used for the Transparent LAN Service over Cable feature must disable Spanning Tree Protocol. Each PVC used for this feature must be configured for AAL5 SNAP encapsulation.

SUMMARY STEPS

1. enable

2. configure terminal

3. bridge 2 protocol ieee

4. interface ATM x/0.y point-to-point

5. bridge group number

6. bridge group number spanning-disabled

7. pvc vpi/vci

8. encapsulation aal5snap

9. exit

10. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable
Router#

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal
Router(config)#

Enters global configuration mode.

Step 3

bridge number protocol ieee
Example:

Router(config)# bridge 2 protocol ieee
Router(config)#

Specifies that the bridge being used should use the IEEE bridge protocol.

Step 4

interface ATM x/0.y point-to-point
Example:

Router(config)# interface ATM 4.0/1 point-to-point
Router(config-if)#

Enters interface configuration mode for the ATM subinterface that will be used for this PVC.

Step 5

bridge-group number
Example:

Router(config-if)# bridge-group 2
Router(config-if)#

Assigns this subinterface to the bridge group that will be used for this particular customer.

Note You cannot mix IEEE 802.1Q and ATM PVC mapping in the same bridge group. To use both types of mappings on the same Cisco CMTS, you must use separate bridge groups.

Step 6

bridge-group number spanning-disabled
Example:

Router(config-if)# bridge-group 2 spanning-disabled
Router(config-if)#

Disables the use of Spanning Tree Protocol on this bridge group.

Step 7

pvc vpi/vci
Example:

Router(config-if)# pvc 1/1
Router(config-if-atm-vc)#

Creates an ATM PVC with the given virtual path identifier (VPI) and virtual channel identifier (VCI), and enters interface-ATM-VC configuration mode.

Step 8

encapsulation aal5snap
Example:

Router(config-if-atm-vc)# encapsulation aal5snap
Router(config-if-atm-vc)#

Configures the PVC for AAL5 SNAP encapsulation.

Step 9

exit
Example:

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

Exits interface-ATM-VC configuration mode.

Note Repeat Step 4 through Step 9 for each PVC to be created.

Step 10

end
Example:

Router(config-if)# end
Router#

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring IEEE 802.1Q VLAN Mapping

This section describes how to enable Layer 2 mapping on the Cisco CMTS, and then to map particular cable modems to an IEEE 802.1Q VLAN.

•Enabling and Configuring Layer 2 Tunneling for IEEE 802.1Q Mapping, page 11

•Creating the IEEE 802.1Q VLAN Bridge Group, page 12

Enabling and Configuring Layer 2 Tunneling for IEEE 802.1Q Mapping

This section describes how to enable Layer 2 mapping on the Cisco CMTS, and then to map particular cable modems to IEEE 802.1Q VLANs on an Ethernet, Fast Ethernet, or Gigabit Ethernet interface.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable l2-vpn-service dot1q

4. encapsulation dot1q vlan-id

5. cable dot1q-vc-map mac-address ethernet-interface vlan-id [cust-name]

6. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable
Router#

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal
Router(config)#

Enters global configuration mode.

Step 3

cable l2-vpn-service dot1q
Example:

Router(config)# cable l2-vpn-service dot1q
Router(config)#

Enables Layer 2 tunneling for IEEE 802.1Q VLAN mapping.

Note It is not required to configure VLAN trunking on the Cisco CMTS. Though VLAN trunking is supported, be aware of additional impact of VLAN trunking on the Cisco CMTS.

Step 4

encapsulation dot1q vlan-id
Example:

Router(config-if)# encapsulation dot1q 10
Router(config-if)#

Enters configuration of the dot1q subinterface and specifies that traffic on the Ethernet link should use IEEE 802.1Q tagging, using the specified vlan-id. The vlan-id can range from 1 to 4095, with no default.

Note This step to perform dot1q encapsulation is not essential for dot1q tagging of frames but it is recommended.

Step 5

cable dot1q-vc-map mac-address ethernet-interface vlan-id [cust-name]
Example:

Router(config)# cable dot1q-vc-map 0000.0C04.0506 FastEthernet0/0 10
Router(config)#

Maps the specified MAC address of a cable modem to the indicated VLAN and Ethernet, Fast Ethernet, or Gigabit Ethernet interface.

Note Repeat this command for each cable modem that is to be mapped to an IEEE 802.1Q VLAN.

Step 6

end
Example:

Router(config)# end
Router#

Exits global configuration mode and returns to privileged EXEC mode.

Creating the IEEE 802.1Q VLAN Bridge Group

This section describes the minimum configuration needed to configure a Cisco router, which is acting as an IEEE 802.1Q VLAN bridge aggregator, so that it can terminate the VLANs being used with the Transparent LAN Service over Cable feature.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface [Ethernet | FastEthernet | GigabitEthernet] x/0

4. ip address ip-address mask

5. interface [Ethernet | FastEthernet | GigabitEthernet] x/0.vlan-id

6. bridge group number

7. end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable
Router#

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal
Router(config)#

Enters global configuration mode.

Step 3

interface [Ethernet | FastEthernet | GigabitEthernet] x/0
Example:

Router(config)# interface fastethernet 1/0
Router(config-if)#

Enters interface configuration mode for the Ethernet interface that is in slot x.

Step 4

ip address ip-address mask
Example:

Router(config-if)# ip address 10.10.10.85 255.255.255.0
Router(config-if)#

Configures the interface with the specified IP address and subnet mask.

Step 5

interface [Ethernet | FastEthernet | GigabitEthernet] x/0.y
Example:

Router(config)# interface fastethernet 1/0.10
Router(config-if)#

Creates a subinterface on the Ethernet interface that is in slot x. The valid range for y is 1 to 4294967293, with no default.

Note Note 1: To simplify network management, set the subinterface number to the same value as the VLAN ID that will use this subinterface (which in this case is 10). The valid range for the subinterface number is 1 to 4095. Note 2: The steps to create a subinterface is not essential for dot1q tagging of frames but it is recommended.

Step 6

bridge group number
Example:

Router(config-if)# bridge group 20
Router(config-if)#

Configures this subinterface to belong to the specified bridge group. The valid range for number is 1 to 255, with no default.

Note You cannot mix IEEE 802.1Q and ATM PVC mapping in the same bridge group. To use both types of mappings on the same Cisco CMTS, you must use separate bridge groups.

Note Repeat steps Step 5 through Step 7 for each subinterface to be created and bridged.

Step 7

end
Example:

Router(config-if)# end
Router#

Exits interface configuration mode and returns to privileged EXEC mode.

Configuration Examples for Transparent LAN Service over Cable

This section lists sample configurations for the Transparent LAN Service over Cable feature on a CMTS router and on a Cisco router acting as an ATM bridge aggregator:

•CMTS ATM PVC Mapping Configuration Example, page 14

•ATM Bridge Aggregator Configuration Example, page 14

•CMTS IEEE 802.1Q VLAN Mapping Configuration Example, page 15

•IEEE 802.1Q Bridge Aggregator Configuration Example, page 15

CMTS ATM PVC Mapping Configuration Example

The following partial configuration for a Cisco uBR7246VXR router shows a typical configuration that creates two ATM PVCs and maps them to two cable modems.
!
hostname "ubr7246vxr"
!
cable l2-vpn-service atm-vc
cable vc-map 0010.7bed.9c95 ATM2/0 1/2
cable vc-map 0007.0e03.69f9 ATM2/0 1/1
!
! 
interface ATM2/0
 no ip address
 no ip route-cache
 no ip mroute-cache
 no atm ilmi-keepalive
!
interface ATM2/0.1 point-to-point
 no ip route-cache
 no ip mroute-cache
 pvc 1/1 
  encapsulation aal5snap
 !
!
interface ATM2/0.2 point-to-point
 no ip route-cache
 no ip mroute-cache
 pvc 1/2 
  encapsulation aal5snap
 !
!
ATM Bridge Aggregator Configuration Example

The following partial configuration for a Cisco 7200 or similar router shows a typical configuration that creates two ATM PVCs and configures them as part of the same ATM bridge group.
hostname IRB-Router
!
bridge irb
bridge 2 protocol ieee 
! 
! 
interface ATM4/0
 no ip address
 no ip directed-broadcast
 no atm enable-ilmi-trap
 no atm ilmi-keepalive
! 
interface ATM4/0.1 point-to-point
 pvc 1/1 
  encapsulation aal5snap
 ! 
 bridge-group 2
 bridge-group 2 spanning-disabled
! 
interface ATM4/0.2 point-to-point
 pvc 1/2 
  encapsulation aal5snap
 ! 
 bridge-group 2
 bridge-group 2 spanning-disabled
CMTS IEEE 802.1Q VLAN Mapping Configuration Example

The following partial configuration for a Cisco uBR7246VXR router shows a typical configuration that shows a number of cable modems being mapped to two different IEEE 802.1Q VLANs.
cable l2-vpn-service dot1q 
! Customer 1 
cable dot1q-vc-map 000C.0e03.69f9 GigabitEthernet 1/0 10 Customer1
cable dot1q-vc-map 0010.7bea.9c95 GigabitEthernet 1/0 11 Customer1
cable dot1q-vc-map 0010.7bed.81c2 GigabitEthernet 1/0 12 Customer1
cable dot1q-vc-map 0010.7bed.9b1a GigabitEthernet 1/0 13 Customer1
! Customer 2 
cable dot1q-vc-map 0002.fdfa.137d GigabitEthernet 1/0 20 Customer2
cable dot1q-vc-map 0006.28f9.9d19 GigabitEthernet 1/0 21 Customer2
cable dot1q-vc-map 000C.7b6b.58c1 GigabitEthernet 1/0 22 Customer2
cable dot1q-vc-map 000C.7bed.9dbb GigabitEthernet 1/0 23 Customer2
cable dot1q-vc-map 000C.7b43.aa7f GigabitEthernet 1/0 24 Customer2
cable dot1q-vc-map 0050.7302.3d83 GigabitEthernet 1/0 25 Customer2
...
IEEE 802.1Q Bridge Aggregator Configuration Example

The following example shows a router being used as a bridge aggregator to transmit VLANs across the same Fast Ethernet interface, using IEEE 802.1Q tagging.
! 
interface GigabitEthernet0/1
 ip address 10.10.10.31 255.255.255.0 
 duplex full 
 speed auto 
!
interface GigabitEthernet0/1.10
 description Customer1-site10 
 encapsulation dot1Q 10 
 bridge-group 200 
interface GigabitEthernet0/1.11
 description Customer1-site11
 encapsulation dot1Q 11
 bridge-group 200 
interface GigabitEthernet0/1.12 
 description Customer1-site12
 encapsulation dot1Q 12
 bridge-group 200 
interface GigabitEthernet0/1.13 
 description Customer1-site13
 encapsulation dot1Q 13 
 bridge-group 200 
!------------------------------------
interface GigabitEthernet0/1.20 
 description Customer2-site20
 encapsulation dot1Q 20
 bridge-group 201 
interface GigabitEthernet0/1.21 
 description Customer2-site21
 encapsulation dot1Q 21
 bridge-group 201 
interface GigabitEthernet0/1.22 
 description Customer2-site22
 encapsulation dot1Q 22
 bridge-group 201 
interface GigabitEthernet0/1.23 
 description Customer2-site23
 encapsulation dot1Q 23
 bridge-group 201 
interface GigabitEthernet0/1.24 
 description Customer2-site24
 encapsulation dot1Q 24
 bridge-group 201 
interface GigabitEthernet0/1.25 
 description Customer2-site25
 encapsulation dot1Q 25
 bridge-group 201 
!
bridge 200 protocol ieee
bridge 201 protocol ieee
...
Additional References

For additional information related to Transparent LAN Service over Cable, refer to the following references:

Related Documents

Related Topic

Document Title

ATM Interface Configuration

Configuring ATM in the Cisco IOS Wide-Area Networking Configuration Guide, Release 12.2, at the following URL:

http://www.cisco.com/en/US/docs/ios/12_2/wan/configuration/guide/wcfatm.html

ATM Interface Command Reference

ATM Commands in the Cisco IOS Wide-Area Networking Command Reference, Release 12.2, at the following URL:

http://www.cisco.com/en/US/docs/ios/12_2/wan/command/reference/fwan_r.html

CMTS Command Reference

Cisco IOS CMTS Cable Command Reference Guide, at the following URL:

http://www.cisco.com/en/US/docs/ios/cable/command/reference/cbl_book.html

Virtual LAN Configuration

Virtual LANS in the Cisco IOS Switching Services Configuration Guide, Release 12.2, at the following URL:

http://www.cisco.com/en/US/docs/ios/12_2/switch/configuration/guide/fswtch_c.html

Virtual LAN Command Reference

Cisco IOS Switching Services Command Reference, Release 12.2, at the following URL:

http://www.cisco.com/en/US/docs/ios/12_2/switch/command/reference/fswtch_r.html

Cisco IOS Release 12.2 Command Reference

Cisco IOS Release 12.2 Configuration Guides and Command References, at the following URL:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_installation_and_configuration_guides_list.html

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/prod_command_reference_list.html

Standards

Standards¹

Title

SP-RFIv1.1-I08-020301

Data-over-Cable Service Interface Specifications Radio Frequency Interface Specification

IEEE 802.1Q, 1998 Edition

IEEE Standards for Local and Metropolitan Area Networks: Virtual Bridged Local Area Networks

¹Not all supported standards are listed.

MIBs

MIBs¹

MIBs Link

No new or modified MIB objects are supported by the Transparent LAN Service over Cable feature.

To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

¹Not all supported MIBs are listed.

RFCs

RFCs¹

Title

RFC 1163

A Border Gateway Protocol

RFC 1164

Application of the Border Gateway Protocol in the Internet

RFC 1483

Multiprotocol Encapsulation over ATM Adaptation Layer 5 (AAL5)

RFC 2233

DOCSIS OSSI Objects Support

RFC 2283

Multiprotocol Extensions for BGP-4

RFC 2665

DOCSIS Ethernet MIB Objects Support

RFC 2669

Cable Device MIB

¹Not all supported RFCs are listed.

Technical Assistance

Description

Link

Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/public/support/tac/home.shtml

Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS CMTS Cable Command Reference at http://www.cisco.com/en/US/docs/ios/cable/command/reference/cbl_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.

•cable dot1q-vc-map

•cable l2-vpn-service atm-vc

•cable l2-vpn-service dot1q

•cable vc-map

•debug cable l2-vpn

•show cable l2-vpn dot1q-vc-map

•show cable l2-vpn vc-map

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