This documentation has been moved
L2VPN: Pseudowire Preferential Forwarding
Downloads: This chapterpdf (PDF - 183.0KB) The complete bookPDF (PDF - 6.7MB) | Feedback

L2VPN: Pseudowire Preferential Forwarding

Table Of Contents

L2VPN: Pseudowire Preferential Forwarding

Finding Feature Information

Contents

Prerequisites for L2VPN: Pseudowire Preferential Forwarding

Restrictions for L2VPN: Pseudowire Preferential Forwarding

Information About L2VPN: Pseudowire Preferential Forwarding

Overview of L2VPN: Pseudowire Preferential Forwarding

How to Configure L2VPN: Pseudowire Preferential Forwarding

Configuring the Pseudowire Connection Between PE Routers

Prerequisites

Configuration Examples for L2VPN: Pseudowire Preferential Forwarding

L2VPN: Pseudowire Preferential Forwarding Configuration: Example

Displaying the Status of the Pseudowires: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for L2VPN: Pseudowire Preferential Forwarding


L2VPN: Pseudowire Preferential Forwarding


First Published: February 27, 2009
Last Updated: May 4, 2009

The L2VPN: Pseudowire Preferential Forwarding feature allows you to configure the pseudowires so that you can use ping and show commands to find status information of the pseudowires before, during, and after a switchover.

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 L2VPN: Pseudowire Preferential Forwarding" 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 L2VPN: Pseudowire Preferential Forwarding

Restrictions for L2VPN: Pseudowire Preferential Forwarding

Information About L2VPN: Pseudowire Preferential Forwarding

How to Configure L2VPN: Pseudowire Preferential Forwarding

Configuration Examples for L2VPN: Pseudowire Preferential Forwarding

Additional References

Feature Information for L2VPN: Pseudowire Preferential Forwarding

Prerequisites for L2VPN: Pseudowire Preferential Forwarding

Before configuring the L2VPN: Pseudowire Preferential Forwarding feature, you should understand the concepts in the following documents:

Preferential Forwarding Status Bit Definition (draft-ietf-pwe3-redundancy-bit-xx.txt)

MPLS Pseudowire Status Signaling

L2VPN Pseudowire Redundancy

NSF/SSO—Any Transport over MPLS and AToM Graceful Restart

MPLS LSP Ping/Traceroute for LDP/TE, and LSP Ping for VCCV

The PE routers must be configured with the following features:

L2VPN Pseudowire Redundancy

NSF/SSO—Any Transport over MPLS and AToM Graceful Restart

The L2VPN: Pseudowire Preferential Forwarding feature requires that the following mechanisms be in place to enable you to detect a failure in the network:

Label switched paths (LSP) Ping/Traceroute and Any Transport over MPLS Virtual Circuit Connection Verification (AToM VCCV)

Local Management Interface (LMI)

Operation, Administration, and Maintenance (OAM)

Restrictions for L2VPN: Pseudowire Preferential Forwarding

Only ATM attachment circuits are supported.

The following features are not supported:

Port mode cell relay

Any Transport over MPLS: AAL5 over MPLS

VC cell packing

OAM emulation

ILMI/PVC-D

Permanent virtual circuit (PVC) Range

L2TPv3 Pseudowire Redundancy

Local switching

Multiple backup pseudowires

Static pseudowires

Information About L2VPN: Pseudowire Preferential Forwarding

The following section provides information about the L2VPN: Pseudowire Preferential Forwarding feature:

Overview of L2VPN: Pseudowire Preferential Forwarding

Overview of L2VPN: Pseudowire Preferential Forwarding

The L2VPN: Pseudowire Preferential Forwarding feature allows you to configure pseudowires so that you can use ping, traceroute, and show commands to find status information before, during, and after a switchover. The implementation of this feature is based on Preferential Forwarding Status Bit Definition (draft-ietf-pwe3-redundancy-bit-xx.txt). The L2VPN: Pseudowire Preferential Forwarding feature provides these enhancements for displaying information about the pseudowires:

You can issue ping mpls commands on the backup pseudowires.

You can display status of the pseudowires before, during, and after a switchover, using the show xconnect and show mpls l2transport vc commands.


Note In a single-segment pseudowire, the PE routers at each end of the pseudowire serve as the termination points. In multisegment pseudowires, the terminating PE routers serve as the termination points.


How to Configure L2VPN: Pseudowire Preferential Forwarding

The following section explains how to configure the L2VPN: Pseudowire Preferential Forwarding feature:

Configuring the Pseudowire Connection Between PE Routers (required)

Configuring the Pseudowire Connection Between PE Routers

You set up a connection, called a pseudowire, between the routers to transmit Layer 2 frames between PE routers.

As part of the pseudowire configuration, issue the status redundancy master command to make it the master. This enables the L2VPN: Pseudowire Preferential Forwarding feature to display the status of the active and backup pseudowires. By default, the PE router is in slave mode.


Note One pseudowire must be the master and the other must be assigned the slave. You cannot configure both pseudowires as master or slave.



Note 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, you receive the following error:
% Incomplete command.


Prerequisites

The PE routers must be configured for the L2VPN Pseudowire Redundancy and NSF/SSO—Any Transport over MPLS and AToM Graceful Restart features. See the following documents for configuration instructions.

L2VPN Pseudowire Redundancy

NSF/SSO—Any Transport over MPLS and AToM Graceful Restart

SUMMARY STEPS

1. enable

2. configure terminal

3. pseudowire-class name

4. encapsulation mpls

5. status redundancy {master | slave}

6. interworking {ethernet | ip}

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 

pseudowire-class name

Example:

Router(config)# pseudowire-class atom

Establishes a pseudowire class with a name that you specify, and enters pseudowire class configuration mode.

Step 4 

encapsulation mpls

Example:

Router(config-pw)# encapsulation mpls

Specifies the tunneling encapsulation.

For AToM, the encapsulation type is mpls.

Step 5 

status redundancy {master | slave}

Example:

Router(config-pw)# status redundancy master

Specifies the pseudowire as the master or slave. This enables the L2VPN: Pseudowire Preferential Forwarding feature to display the status of the active and backup pseudowires.

By default, the PE router is in slave mode.

Note One pseudowire must be the master and the other must be assigned the slave. You cannot configure both pseudowires as master or slave.

Step 6 

interworking {ethernet | ip}

Example:

Router(config-pw)# interworking ip

(Optional) Enables the translation between the different Layer 2 encapsulations.

Configuration Examples for L2VPN: Pseudowire Preferential Forwarding

This section contains the following examples:

L2VPN: Pseudowire Preferential Forwarding Configuration: Example

Displaying the Status of the Pseudowires: Example

L2VPN: Pseudowire Preferential Forwarding Configuration: Example

The following commands configure a PE router with the L2VPN: Pseudowire Preferential Forwarding feature:

mpls ldp graceful-restart
mpls ip
mpls label protocol ldp
mpls ldp router-id Loopback0 force
mpls ldp advertise-labels
!
pseudowire-class mpls
 encapsulation mpls
 status redundancy master

interface ATM0/2/0.1 multipoint
 logging event subif-link-status
 atm pvp 50 l2transport
  xconnect 10.1.1.2 100 encap mpls 
   backup peer 10.1.1.3 100 encap mpls
end

Displaying the Status of the Pseudowires: Example

The following examples show the status of the active and backup pseudowires before, during, and after a switchover.

The show mpls l2transport vc command on the active PE router displays the status of the pseudowires:


Router# show mpls l2transport vc

Local intf     Local circuit              Dest address    VC ID      Status    
-------------  -------------------------- --------------- ---------- ----------
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.2         100        UP        
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.3         100        STANDBY   

The show mpls l2transport vc command on the backup PE router displays the status of the pseudowires. The active pseudowire on the backup PE router has the HOTSTANDBY status.


Router1-standby# show mpls l2transport vc
 
Local intf     Local circuit              Dest address    VC ID      Status    
-------------  -------------------------- --------------- ---------- ----------
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.2         100        HOTSTANDBY
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.3         100        DOWN      

During a switchover, the status of the active and backup pseudowires changes:

Router# show mpls l2transport vc

Local intf     Local circuit              Dest address    VC ID      Status    
-------------  -------------------------- --------------- ---------- ----------
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.2         100        RECOVERING
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.3         100        DOWN      

After the switchover is complete, the recovering pseudowire shows a status of UP:

Router# show mpls l2transport vc

Local intf     Local circuit              Dest address    VC ID      Status    
-------------  -------------------------- --------------- ---------- ----------
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.2         100        UP        
AT0/2/0/0.1    ATM VPC CELL 50            10.1.1.3         100        STANDBY   

The show xconnect command displays the standby (SB) state for the backup pseudowire, which is independent of the stateful switchover mode of the router:

Router# show xconnect all

Legend:    XC ST=Xconnect State  S1=Segment1 State  S2=Segment2 State
  UP=Up       DN=Down            AD=Admin Down      IA=Inactive
  SB=Standby  HS=Hot Standby     RV=Recovering      NH=No Hardware

XC ST        Segment 1                                  S1 Segment 2                                  
S2
------+---------------------------------+--+---------------------------------+---------
UP pri ac   AT1/1/0/0.1/1/1:220/220(ATM V  UP mpls 10.193.193.3:330            UP
IA sec ac   AT1/1/0/0.1/1/1:220/220(ATM V  UP mpls 10.193.193.3:331            SB

The ping mpls and traceroute mpls commands show that the dataplane is active on the backup pseudowire:

Router# ping mpls pseudowire 10.193.193.22 331

%Total number of MS-PW segments is less than segment number; Adjusting the segment number 
to 1
Sending 5, 100-byte MPLS Echos to 10.193.193.22,
     timeout is 2 seconds, send interval is 0 msec:

Codes: '!' - success, 'Q' - request not sent, '.' - timeout,
  'L' - labeled output interface, 'B' - unlabeled output interface,
  'D' - DS Map mismatch, 'F' - no FEC mapping, 'f' - FEC mismatch,
  'M' - malformed request, 'm' - unsupported tlvs, 'N' - no label entry,
  'P' - no rx intf label prot, 'p' - premature termination of LSP,
  'R' - transit router, 'I' - unknown upstream index,
  'X' - unknown return code, 'x' - return code 0

Type escape sequence to abort.
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
 
Router# traceroute mpls pseudowire 10.193.193.22 331 segment 1

Tracing MS-PW segments within range [1-1] peer address 10.193.193.22 and timeout 2 seconds

Codes: '!' - success, 'Q' - request not sent, '.' - timeout,
  'L' - labeled output interface, 'B' - unlabeled output interface,
  'D' - DS Map mismatch, 'F' - no FEC mapping, 'f' - FEC mismatch,
  'M' - malformed request, 'm' - unsupported tlvs, 'N' - no label entry,
  'P' - no rx intf label prot, 'p' - premature termination of LSP,
  'R' - transit router, 'I' - unknown upstream index,
  'X' - unknown return code, 'x' - return code 0

Type escape sequence to abort.
! 1 10.193.33.22 4 ms [Labels: 23 Exp: 0]
    local 10.193.193.3 remote 10.193.193.22 vc id 331

Additional References

The following sections provide references related to the L2VPN: Pseudowire Preferential Forwarding feature.

Related Documents

Related Topic
Document Title

Description of commands associated with MPLS and MPLS applications

Cisco IOS Multiprotocol Label Switching Command Reference

L2VPN Pseudowires

L2VPN Pseudowire Redundancy

MPLS Pseudowire Status Signaling

NSF/SSO for L2VPNs

NSF/SSO—Any Transport over MPLS and AToM Graceful Restart

Ping and Traceroute for L2VPNs

MPLS LSP Ping/Traceroute for LDP/TE, and LSP Ping for VCCV


Standards

Standard
Title

draft-ietf-pwe3-redundancy-bit-xx.txt

Preferential Forwarding Status Bit Definition


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported by this feature, and support for existing standards has not been modified by this feature.


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 L2VPN: Pseudowire Preferential Forwarding

Table 1 lists the release history for this feature 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 L2VPN: Pseudowire Preferential Forwarding 

Feature Name
Releases
Feature Information

L2VPN: Pseudowire Preferential Forwarding

Cisco IOS XE Release 2.3

This feature allows you to configure the pseudowires so that you can use ping and show commands to find status information of the pseudowires before, during, and after a switchover.

The following sections provide information about this feature:

Information About L2VPN: Pseudowire Preferential Forwarding

How to Configure L2VPN: Pseudowire Preferential Forwarding

The following commands were introduced or modified: show mpls l2transport vc, show xconnect, status redundancy.