L2VPN Pseudowire Switching
Finding Feature Information
Restrictions for L2VPN Pseudowire Switching
Information About L2VPN Pseudowire Switching
- How L2VPN Pseudowire Switching Works
- How Packets Are Manipulated at the Aggregation Point
How to Configure L2VPN Pseudowire Switching
- Configuring
How to Configure L2VPN Pseudowire Switching using the commands associated with the L2VPN Protocol-Based CLIs feature
- Configuring
Configuration Examples for L2VPN Pseudowire Switching
- L2VPN Pseudowire Switching in an Inter-AS Configuration Example
Additional References
Feature Information for L2VPN Pseudowire Switching

L2VPN Pseudowire Switching

This feature module explains how to configure L2VPN Pseudowire Switching, which extends layer 2 virtual private network (L2VPN) pseudowires across an interautonomous system (inter-AS) boundary or across two separate multiprotocol label switching (MPLS) networks.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table.

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

Restrictions for L2VPN Pseudowire Switching

In Cisco IOS XE Release 2.4, Pseudowire Switching is supported on Ethernet over MPLS attachment circuits.
L2VPN Pseudowire Switching is supported with AToM.
Only static, on-box provisioning is supported.
Sequencing numbers in AToM packets are not processed by L2VPN Pseudowire Switching. The feature blindly passes the sequencing data through the xconnect packet paths, a process that is called transparent sequencing. The endpoint PE-CE connections enforce the sequencing.
You can ping the adjacent next-hop PE router. End-to-end LSP pings are not supported.
Do not configure IP or Ethernet interworking on a router where L2VPN Pseudowire Switching is enabled. Instead, configure interworking on the routers at the edge PEs of the network.
The control word negotiation results must match. If either segment does not negotiate the control word, the control word is disabled for both segments.
AToM Graceful Restart is negotiated independently on each pseudowire segment. If there is a transient loss of the LDP session between two AToM PE routers, packets continue to flow.
Per-pseudowire quality of service (QoS) is not supported. Traffic Engineering (TE) tunnel selection is supported.
Attachment circuit interworking is not supported.

Information About L2VPN Pseudowire Switching

How L2VPN Pseudowire Switching Works

L2VPN Pseudowire Switching allows the user to extend L2VPN pseudowires across an inter-AS boundary or across two separate MPLS networks, as shown in the figures below. L2VPN Pseudowire Switching connects two or more contiguous pseudowire segments to form an end-to-end multihop pseudowire. This end-to-end pseudowire functions as a single point-to-point pseudowire.

As shown in the second figure below, L2VPN Pseudowire Switching enables you to keep the IP addresses of the edge PE routers private across inter-AS boundaries. You can use the IP address of the autonomous system boundary routers (ASBRs) and treat them as pseudowire aggregation (PE-agg) routers. The ASBRs join the pseudowires of the two domains.

L2VPN Pseudowire Switching also enables you to keep different administrative or provisioning domains to manage the end-to-end service. At the boundaries of these networks, PE-agg routers delineate the management responsibilities.

Figure 1. L2VPN Pseudowire Switching in an Intra-AS Topology

Figure 2. L2VPN Pseudowire Switching in an Inter-AS Topology

How Packets Are Manipulated at the Aggregation Point

Switching AToM packets between two AToM pseudowires is the same as switching any MPLS packet. The MPLS switching data path switches AToM packets between two AToM pseudowires. The following list explains exceptions:

The outgoing virtual circuit (VC) label replaces the incoming VC label in the packet. New Internal Gateway Protocol (IGP) labels and Layer 2 encapsulation are added.
The incoming VC label time-to-live (TTL) field is decremented by one and copied to the outgoing VC label TTL field.
The incoming VC label EXP value is copied to the outgoing VC label EXP field.
The outgoing VC label ‘Bottom of Stack’ S bit in the outgoing VC label is set to1.
AToM control word processing is not performed at the L2VPN Pseudowire Switching aggregation point. Sequence numbers are not validated. Use the Router Alert label for LSP Ping; do not require control word inspection to determine an LSP Ping packet.

How to Configure L2VPN Pseudowire Switching

Configuring

Use the following procedure to configure L2VPN Pseudowire Switching on each of the PE-agg routers.

Before you begin

This procedure assumes that you have configured basic AToM L2VPNs. This procedure does not explain how to configure basic AToM L2VPNs that transport Layer 2 packets over an MPLS backbone. For information on the basic configuration, see Any Transport over MPLS.
For inter-Autonomous configurations, ASBRs require a labeled interface.

Note

In this configuration, you are limited to two neighbor commands after entering the l2 vfi command.

SUMMARY STEPS

enable
configure terminal
l2 vfi name point-to-point
neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name
exit
exit
show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max ]] [interface name [local-circuit-id ]] [destination ip-address | name ] [detail ]
show vfi [vfi-name ]
ping [protocol ] [tag ] {host-name | system-address }

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

l2 vfi name point-to-point

Example:


Router(config)# l2 vfi atomtunnel point-to-point

Creates a point-to-point Layer 2 virtual forwarding interface (VFI) and enters VFI configuration mode.

Step 4

neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name

Example:


Router(config-vfi)# neighbor 10.0.0.1 100 pw-class mpls

Sets up an emulated VC. Specify the IP address and the VC ID of the remote router. Also specify the pseudowire class to use for the emulated VC.

Note

Only two neighbor commands are allowed for each l2 vfi point-to-point command.

Step 5

exit

Example:


Router(config-vfi)# exit

Exits VFI configuration mode.

Step 6

exit

Example:


Router(config)# exit

Exits global configuration mode.

Step 7

show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max ]] [interface name [local-circuit-id ]] [destination ip-address | name ] [detail ]

Example:


Router# show mpls l2transport vc

Verifies that the L2VPN Pseudowire Switching session has been established.

Step 8

show vfi [vfi-name ]

Example:


Router# show  vfi  atomtunnel

Verifies that a point-to-point VFI has been established.

Step 9

ping [protocol ] [tag ] {host-name | system-address }

Example:


Router# ping 10.1.1.1

When issued from the CE routers, this command verifies end-to-end connectivity.

Examples

The following example displays the output of the show mpls l2transport vc command:


Router# show mpls l2transport vc
Local intf     Local circuit              Dest address    VC ID Status   
-------------  -------------------------- --------------- ----- ---- 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP

The following example displays the output of the show vfi command:


Router# show vfi
VFI name: test, type: point-to-point
 Neighbors connected via pseudowires:
   Router ID        Pseudowire ID
   10.0.1.1         100      
   10.0.1.1         100

How to Configure L2VPN Pseudowire Switching using the commands associated with the L2VPN Protocol-Based CLIs feature

Perform this task to configure L2VPN Pseudowire Switching on each of the PE-agg routers. In this configuration, you are limited to two neighbor commands after entering the l2vpn xconnect command.

Before you begin

This task assumes that you have configured basic AToM L2VPNs. This task does not explain how to configure basic AToM L2VPNs that transport Layer 2 packets over an MPLS backbone. For information on the basic configuration, see the “Any Transport over MPLS” section.
For interautonomous configurations, autonomous system boundary routers (ASBRs) require a labeled interface.

SUMMARY STEPS

enable
configure terminal
interface pseudowire number
encapsulation mpls
neighbor peer-address vcid-value
exit
interface pseudowire number
encapsulation mpls
neighbor peer-address vcid-value
exit
l2vpn xconnect context context-name
member pseudowire interface-number
member ip-address vcid encapsulation mpls
member pseudowire interface-number
member ip-address vcid encapsulation mpls
exit
exit
show l2vpn atom vc [vcid [vc-id | vc-id-min vc-id-max ]] [interface type number [local-circuit-id ]] [destination ip-address | name ] [detail ]
ping [protocol ] [tag ] {hostname | system-address }

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface pseudowire number

Example:


Router(config)# interface pseudowire 100

Specifies the pseudowire interface and enters interface configuration mode.

Step 4

encapsulation mpls

Example:


Router(config-if)# encapsulation mpls

Specifies that Multiprotocol Label Switching (MPLS) is used as the data encapsulation method.

Step 5

neighbor peer-address vcid-value

Example:


Router(config-if)# neighbor 10.0.0.1 123

Specifies the peer IP address and virtual circuit (VC) ID value of the Layer 2 VPN (L2VPN) pseudowire.

Step 6

exit

Example:


Router(config-if)# exit

Exits interface configuration mode.

Step 7

interface pseudowire number

Example:


Router(config)# interface pseudowire 200

Specifies the pseudowire interface and enters interface configuration mode.

Step 8

encapsulation mpls

Example:


Router(config-if)# encapsulation mpls

Specifies that Multiprotocol Label Switching (MPLS) is used as the data encapsulation method.

Step 9

neighbor peer-address vcid-value

Example:


Router(config-if)# neighbor 10.0.0.2 124

Specifies the peer IP address and virtual circuit (VC) ID value of the Layer 2 VPN (L2VPN) pseudowire.

Step 10

exit

Example:


Router(config-if)# exit

Exits interface configuration mode.

Step 11

l2vpn xconnect context context-name

Example:


Device(config)# l2vpn xconnect context con1

Creates a Layer 2 VPN (L2VPN) cross connect context and enters xconnect configuration mode.

Step 12

member pseudowire interface-number

Example:


Router(config-xconnect)# member pseudowire 100

Specifies a member pseudowire to form a Layer 2 VPN (L2VPN) cross connect.

Step 13

member ip-address vcid encapsulation mpls

Example:


Device(config-xconnect)# member 10.0.0.1 123 encapsulation mpls

Specifies the devices that form a point-to-point Layer 2 VPN (L2VPN) virtual forwarding interface (VFI) connection.

Note

Only two member commands are allowed for each l2vpn xconnect context command.

Step 14

member pseudowire interface-number

Example:


Router(config-xconnect)# member pseudowire 200

Specifies a member pseudowire to form a Layer 2 VPN (L2VPN) cross connect.

Step 15

member ip-address vcid encapsulation mpls

Example:


Device(config-xconnect)# member 10.0.0.2 124 encapsulation mpls

Specifies the devices that form a point-to-point Layer 2 VPN (L2VPN) virtual forwarding interface (VFI) connection.

Note

Only two member commands are allowed for each l2vpn xconnect context command.

Step 16

exit

Example:


Device(config-xconnect)# exit

Exits Xconnect configuration mode.

Step 17

exit

Example:


Device(config)# exit

Exits global configuration mode.

Step 18

show l2vpn atom vc [vcid [vc-id | vc-id-min vc-id-max ]] [interface type number [local-circuit-id ]] [destination ip-address | name ] [detail ]

Example:


Device# show l2vpn atom vc

Displays information about Any Transport over MPLS (AToM) virtual circuits (VCs) and static pseudowires that have been enabled to route Layer 2 packets on a device.

Step 19

ping [protocol ] [tag ] {hostname | system-address }

Example:


Device# ping 10.1.1.1

When issued from the CE routers, verifies end-to-end connectivity.

Configuring

Use the following procedure to configure L2VPN Pseudowire Switching on each of the PE-agg routers.

Before you begin

This procedure assumes that you have configured basic AToM L2VPNs. This procedure does not explain how to configure basic AToM L2VPNs that transport Layer 2 packets over an MPLS backbone. For information on the basic configuration, see Any Transport over MPLS.
For inter-Autonomous configurations, ASBRs require a labeled interface.

Note

In this configuration, you are limited to two neighbor commands after entering the l2 vfi command.

SUMMARY STEPS

enable
configure terminal
l2 vfi name point-to-point
neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name
exit
exit
show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max ]] [interface name [local-circuit-id ]] [destination ip-address | name ] [detail ]
show vfi [vfi-name ]
ping [protocol ] [tag ] {host-name | system-address }

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

l2 vfi name point-to-point

Example:


Router(config)# l2 vfi atomtunnel point-to-point

Creates a point-to-point Layer 2 virtual forwarding interface (VFI) and enters VFI configuration mode.

Step 4

neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name

Example:


Router(config-vfi)# neighbor 10.0.0.1 100 pw-class mpls

Sets up an emulated VC. Specify the IP address and the VC ID of the remote router. Also specify the pseudowire class to use for the emulated VC.

Note

Only two neighbor commands are allowed for each l2 vfi point-to-point command.

Step 5

exit

Example:


Router(config-vfi)# exit

Exits VFI configuration mode.

Step 6

exit

Example:


Router(config)# exit

Exits global configuration mode.

Step 7

show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max ]] [interface name [local-circuit-id ]] [destination ip-address | name ] [detail ]

Example:


Router# show mpls l2transport vc

Verifies that the L2VPN Pseudowire Switching session has been established.

Step 8

show vfi [vfi-name ]

Example:


Router# show  vfi  atomtunnel

Verifies that a point-to-point VFI has been established.

Step 9

ping [protocol ] [tag ] {host-name | system-address }

Example:


Router# ping 10.1.1.1

When issued from the CE routers, this command verifies end-to-end connectivity.

Examples

The following example displays the output of the show mpls l2transport vc command:


Router# show mpls l2transport vc
Local intf     Local circuit              Dest address    VC ID Status   
-------------  -------------------------- --------------- ----- ---- 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP

The following example displays the output of the show vfi command:


Router# show vfi
VFI name: test, type: point-to-point
 Neighbors connected via pseudowires:
   Router ID        Pseudowire ID
   10.0.1.1         100      
   10.0.1.1         100

Configuration Examples for L2VPN Pseudowire Switching