Table Of Contents
Prerequisites for L2VPN Pseudowire Redundancy
Restrictions for L2VPN Pseudowire Redundancy
Information About L2VPN Pseudowire Redundancy
Introduction to L2VPN Pseudowire Redundancy
How to Configure L2VPN Pseudowire Redundancy
Configuring L2VPN Pseudowire Redundancy
Forcing a Manual Switchover to the Backup Pseudowire VC
Verifying the L2VPN Pseudowire Redundancy Configuration
Configuration Examples for L2VPN Pseudowire Redundancy
L2VPN Pseudowire Redundancy and AToM (Like to Like): Examples
L2VPN Pseudowire Redundancy and L2VPN Interworking: Examples
L2VPN Pseudowire Redundancy with Layer 2 Local Switching: Examples
Feature Information for L2VPN Pseudowire Redundancy
L2VPN Pseudowire Redundancy
First Published: April 20, 2005Last Updated: February 27, 2009The L2VPN Pseudowire Redundancy feature lets you configure your network to detect a failure in the network and reroute the Layer 2 (L2) service to another endpoint that can continue to provide service. This feature provides the ability to recover from a failure either of the remote provider edge (PE) router or of the link between the PE and customer edge (CE) routers.
Finding Feature Information
Your software release may not support all the features documented in this module. 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 L2VPN Pseudowire Redundancy" 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
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Prerequisites for L2VPN Pseudowire Redundancy
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Prerequisites for L2VPN Pseudowire Redundancy
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Restrictions for L2VPN Pseudowire Redundancy
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Information About L2VPN Pseudowire Redundancy
Make sure that you understand the following concept before configuring the L2VPN Pseudowire Redundancy feature:
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Introduction to L2VPN Pseudowire Redundancy
L2VPNs can provide pseudowire resiliency through their routing protocols. When connectivity between end-to-end PE routers fails, an alternative path to the directed LDP session and the user data can take over. However, there are some parts of the network where this rerouting mechanism does not protect against interruptions in service. Figure 1 shows those parts of the network that are vulnerable to an interruption in service.
Figure 1 Points of Potential Failure in an L2VPN Network
The L2VPN Pseudowire Redundancy feature provides the ability to ensure that the CE2 router in Figure 1 can always maintain network connectivity, even if one or all the failures in the figure occur.
The L2VPN Pseudowire Redundancy feature enables you to set up backup pseudowires. You can configure the network with redundant pseudowires (PWs) and redundant network elements, which are shown in Figure 2, Figure 3, and Figure 4.
Figure 2 shows a network with redundant pseudowires and redundant attachment circuits.
Figure 2 L2VPN Network with Redundant PWs and Attachment Circuits
Figure 3 shows a network with redundant pseudowires, attachment circuits, and CE routers.
Figure 3 L2VPN Network with Redundant PWs, Attachment Circuits, and CE Routers
Figure 4 shows a network with redundant pseudowires, attachment circuits, CE routers, and PE routers.
Figure 4 L2VPN Network with Redundant PWs, Attachment Circuits, CE Routers,
and PE Routers
How to Configure L2VPN Pseudowire Redundancy
The L2VPN Pseudowire Redundancy feature enables you to configure a backup pseudowire in case the primary pseudowire fails. When the primary pseudowire fails, the PE router can switch to the backup pseudowire. You can have the primary pseudowire resume operation after it comes back up.
The following sections explain how to configure the L2VPN Pseudowire Redundancy feature:
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Configuring the Pseudowire
The successful transmission of the Layer 2 frames between PE routers is due to the configuration of the PE routers. You set up the connection, called a pseudowire, between the routers.
The pseudowire-class configuration group specifies the characteristics of the tunneling mechanism, which are:
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You must specify the encapsulation mpls command as part of the pseudowire class for the AToM VCs to work properly. If you omit the encapsulation mpls command as part of the xconnect command, you receive the following error:
% Incomplete command.Perform this task to configure a pseudowire class.
SUMMARY STEPS
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DETAILED STEPS
Configuring L2VPN Pseudowire Redundancy
Use the following steps to configure the L2VPN Pseudowire Redundancy feature.
Prerequisites
For each transport type, the xconnect command is configured slightly differently. The following configuration steps use Ethernet VLAN over MPLS, which is configured in subinterface configuration mode. See Any Transport over MPLS to determine how to configure the xconnect command for other transport types.
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Forcing a Manual Switchover to the Backup Pseudowire VC
To force the router switch over to the backup or primary pseudowire, you can enter the xconnect backup force switchover command in privileged EXEC mode. You can specify either the interface of the primary attachment circuit (AC) to switch to or the IP-address and VC ID of the peer router.
A manual switchover can be made only if the interface or peer specified in the command is actually available and the xconnect will move to the fully active state when the command is entered.
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Verifying the L2VPN Pseudowire Redundancy Configuration
Use the following commands to verify that the L2VPN Pseudowire Redundancy feature is correctly configured.
SUMMARY STEPS
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DETAILED STEPS
Step 1
In this example, the primary attachment circuit is up. The backup attachment circuit is available, but not currently selected. The show output displays as follows:
Router# show mpls l2transport vcLocal intf Local circuit Dest address VC ID Status------------- ----------------------- --------------- ---------- ----------Et0/0.1 Eth VLAN 101 10.0.0.2 101 UPEt0/0.1 Eth VLAN 101 10.0.0.3 201 DOWNRouter# show mpls l2transport vc detailLocal interface: Et0/0.1 up, line protocol up, Eth VLAN 101 upDestination address 10.0.0.2 VC ID: 101, VC status UP...Local interface: Et0/0.1 down, line protocol down, Eth VLAN 101 downDestination address 10.0.0.3 VC ID: 201, VC status down...Step 2
In this example, the topology is Attachment Circuit 1 to Pseudowire 1 with a Pseudowire 2 as a backup:
Router# show xconnect allLegend: XC ST=Xconnect State, S1=Segment1 State, S2=Segment2 StateUP=Up, DN=Down, AD=Admin Down, IA=Inactive, NH=No HardwareXC ST Segment 1 S1 Segment 2 S2------+---------------------------------+--+---------------------------------+--UP pri ac Et0/0(Ethernet) UP mpls 10.55.55.2:1000 UPIA sec ac Et0/0(Ethernet) UP mpls 10.55.55.3:1001 DNIn this example, the topology is Attachment Circuit 1 to Attachment Circuit 2 with a Pseudowire backup for Attachment Circuit 2:
Router# show xconnect allLegend: XC ST=Xconnect State, S1=Segment1 State, S2=Segment2 StateUP=Up, DN=Down, AD=Admin Down, IA=Inactive, NH=No HardwareXC ST Segment 1 S1 Segment 2 S2------+---------------------------------+--+---------------------------------+--UP pri ac Se6/0:150(FR DLCI) UP ac Se8/0:150(FR DLCI) UPIA sec ac Se6/0:150(FR DLCI) UP mpls 10.55.55.3:7151 DNStep 3
In addition to the show mpls l2transport vc command and the show xconnect command, you can use the xconnect logging redundancy command to track the status of the xconnect redundancy group:
Router(config)# xconnect logging redundancyWhen this command is configured, the following messages will be generated during switchover events:
Activating the primary member:
00:01:07: %XCONNECT-5-REDUNDANCY: Activating primary member 10.55.55.2:1000Activating the backup member:
00:01:05: %XCONNECT-5-REDUNDANCY: Activating secondary member 10.55.55.3:1001Configuration Examples for L2VPN Pseudowire Redundancy
The following sections show the L2VPN Pseudowire Redundancy feature examples. These configuration examples show how the L2VPN Pseudowire Redundancy feature can be configured with the AToM (like-to-like), L2VPN Interworking, and Layer 2 Local Switching features.
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Each of the configuration examples refers to one of the following pseudowire classes:
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pseudowire-class mplsencapsulation mpls•
pseudowire-class mpls-ipencapsulation mplsinterworking ipL2VPN Pseudowire Redundancy and AToM (Like to Like): Examples
The following example shows a High-Level Data Link Control (HDLC) attachment circuit xconnect with a backup pseudowire:
interface Serial4/0xconnect 10.55.55.2 4000 pw-class mplsbackup peer 10.55.55.3 4001 pw-class mplsThe following example shows a Frame Relay attachment circuit xconnect with a backup pseudowire:
connect fr-fr-pw Serial6/0 225 l2transportxconnect 10.55.55.2 5225 pw-class mplsbackup peer 10.55.55.3 5226 pw-class mplsL2VPN Pseudowire Redundancy and L2VPN Interworking: Examples
The following example shows an Ethernet attachment circuit xconnect with L2VPN IP interworking and a backup pseudowire:
interface Ethernet0/0xconnect 10.55.55.2 1000 pw-class mpls-ipbackup peer 10.55.55.3 1001 pw-class mpls-ipThe following example shows an Ethernet VLAN attachment circuit xconnect with L2VPN IP interworking and a backup pseudowire:
interface Ethernet1/0.1encapsulation dot1Q 200no ip directed-broadcastxconnect 10.55.55.2 5200 pw-class mpls-ipbackup peer 10.55.55.3 5201 pw-class mpls-ipThe following example shows a Frame Relay attachment circuit xconnect with L2VPN IP interworking and a backup pseudowire:
connect fr-ppp-pw Serial6/0 250 l2transportxconnect 10.55.55.2 8250 pw-class mpls-ipbackup peer 10.55.55.3 8251 pw-class mpls-ipThe following example shows a PPP attachment circuit xconnect with L2VPN IP interworking and a backup pseudowire:
interface Serial7/0encapsulation pppxconnect 10.55.55.2 2175 pw-class mpls-ipbackup peer 10.55.55.3 2176 pw-class mpls-ipL2VPN Pseudowire Redundancy with Layer 2 Local Switching: Examples
The following example shows an Ethernet VLAN-VLAN local switching xconnect with a pseudowire backup for Ethernet segment E2/0.2. If the subinterface associated with E2/0.2 goes down, the backup pseudowire is activated.
connect vlan-vlan Ethernet1/0.2 Ethernet2/0.2backup peer 10.55.55.3 1101 pw-class mplsThe following example shows a Frame Relay-to-Frame Relay local switching connect with a pseudowire backup for Frame Relay segment S8/0 150. If data-link connection identifier (DLCI) 150 on S8/0 goes down, the backup pseudowire is activated.
connect fr-fr-ls Serial6/0 150 Serial8/0 150backup peer 10.55.55.3 7151 pw-class mplsAdditional References
The following sections provide references related to the L2VPN Pseudowire Redundancy feature.
Related Documents
Cisco IOS XE Multiprotocol Label Switching configuration tasks
Cisco IOS XE Multiprotocol Label Switching Configuration Guide, Release 2
Cisco IOS XE Wide-Area Networking configuration tasks
Cisco IOS XE Wide-Area Networking Configuration Guide, Release 2
Wide-Area networking commands
Standards
MIBs
RFCs
Technical Assistance
Feature Information for L2VPN Pseudowire Redundancy
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 Feature Information for L2VPN Pseudowire Redundancy
L2VPN Pseudowire Redundancy
Cisco IOS XE Release 2.3
This feature enables you to set up your network to detect a failure in the network and reroute the Layer 2 service to another endpoint that can continue to provide service.
In Cisco IOS XE Release 2.3, this feature was integrated into the Cisco ASR 1000 series routers.
The following sections provide information about this feature:
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The following commands were introduced or modified: backup delay (L2VPN local switching), backup peer, show xconnect, xconnect backup force-switchover, xconnect logging redundancy.
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