Cisco IOS High Availability Configuration Guide, Release 12.2SR
NSF/SSO—Any Transport over MPLS and AToM Graceful Restart
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Table Of Contents

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

Contents

Prerequisites for AToM NSF

Supported Hardware

Supported Port Adapters

Supported RSPs

Supported VIPs

Neighbor Routers in the MPLS HA Environment

Stateful Switchover

Nonstop Forwarding for Routing Protocols

Restrictions for AToM NSF

Information About AToM NSF

How AToM NSF Works

Checkpointing AToM Information

Checkpointing Troubleshooting Tips

How to Configure AToM NSF

Configuring AToM

Configuring SSO on the Route Processors

Configuring Nonstop Forwarding on the Routers

Configuring MPLS LDP Graceful Restart

Verifying the Configuration

Configuration Examples for AToM NSF

Ethernet to VLAN Interworking with AToM NSF: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Feature Information for AToM NSF


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

First Published: August 11, 2004
Last Updated: February 23, 2006

Cisco nonstop forwarding (NSF) with stateful switchover (SSO) is effective at increasing availability of network services. Cisco NSF with SSO provides continuous packet forwarding, even during a network processor hardware or software failure. In a redundant system, the secondary processor recovers control plane service during a critical failure in the primary processor. SSO synchronizes the network state information between the primary and the secondary processor.

Any Transport over MPLS (AToM) uses NSF, SSO, and Graceful Restart to allow a Route Processor (RP) to recover from a disruption in control plane service without losing its MPLS forwarding state.

Note In this document, the NSF/SSO—Any Transport over MPLS and AToM Graceful Restart feature is referred to as AToM NSF for brevity.

Finding Feature Information in This Module

Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for AToM NSF" section.

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

•Prerequisites for AToM NSF

•Restrictions for AToM NSF

•Information About AToM NSF

•How to Configure AToM NSF

•Configuration Examples for AToM NSF

•Additional References

•Command Reference

•Feature Information for AToM NSF

Prerequisites for AToM NSF

This section lists the following prerequisites:

•Supported Hardware

•Neighbor Routers in the MPLS HA Environment

•Stateful Switchover

•Nonstop Forwarding for Routing Protocols

Supported Hardware

The AToM NSF feature is supported on the Cisco 7500 series routers, with the port adapters, versatile interface processors (VIPs), and route switch processors (RSPs) listed in the following sections.

Supported Port Adapters

•GEIP+

•PA-2FE-TX, PA-2FE-FX

•PA-2H, PA-H

•PA-4E, PA-8E

•PA-4T+ and/or PA-8T-232, PA-8T-V35, PA-8T-X21

•PA-A3-OC3-MM, PA-A3-OC3-SMI, PA-A3-OC3-SML

•PA-FE-TX, PA-FE-FX

•PA-MC_8E1/120, MC-4E1, MC-2E1, MC-8T1, MC-4T1, MC-2T1

•PA-MC-8E1IMA

•PA-MC-8TE1+

•PA-MC-E3

•PA-MC-STM1-MM, PA-MC-STM1-SMI

•PA-MC-T3, PA-MC-2T3+

•PA-POS-OC3-MM, PA-POS-OC3-SMI, PA-POS-OC3-SML

Supported RSPs

•RSP4

•RSP4+

•RSP8

•RSP16

Supported VIPs

•VIP2-50

•VIP4-50

•VIP4-80

•VIP6-80

Neighbor Routers in the MPLS HA Environment

AToM NSF requires that neighbor networking devices be able to perform AToM GR. The Cisco 7200 and Cisco 7500 routers are capable of supporting AToM GR and can be used as neighbor networking devices.

Stateful Switchover

To perform AToM NSF, Route Processors must be configured for SSO and Graceful Restart. See the Stateful Switchover feature module for more information.

Nonstop Forwarding for Routing Protocols

You must enable NSF on the routing protocols running between the provider (P) routers, provider edge (PE) routers, and customer edge (CE) routers. The routing protocols are the following:

•Border Gateway Protocol (BGP)

•Open Shortest Path First (OSPF)

•Intermediate System-to-Intermediate System (IS-IS)

See the Cisco Nonstop Forwarding feature module for more information.

Restrictions for AToM NSF

AToM NSF includes the following restrictions:

•Tag Distribution Protocol (TDP) sessions are not supported. Only Label Distribution Protocol (LDP) sessions are supported.

•AToM NSF cannot be configured on label-controlled ATM (LC-ATM) interfaces.

•AToM NSF supports AToM L2VPN Interworking. However, Layer 2 Tunnel Protocol Version 3 (L2TPv3) Interworking is not supported.

•AToM NSF interoperates with Layer 2 Local Switching. However, AToM NSF has no effect on interfaces configured for local switching.

•Disable fair queueing on serial interfaces or distributed Cisco Express Forwarding will not work on the interfaces.

•On the Cisco 7500 series routers, distributed Cisco Express Forwarding is needed to support AToM NSF.

Information About AToM NSF

To configure AToM NSF, you should understand the following concepts:

•How AToM NSF Works

•Checkpointing AToM Information

How AToM NSF Works

AToM NSF improves the availability of a service provider's network that uses AToM to provide Layer 2 VPN services to its customers. HA provides the ability to detect failures and handle them with minimal disruption to the service being provided. AToM NSF is achieved by SSO and NSF mechanisms. A standby RP provides control-plane redundancy. The control plane state and data plane provisioning information for the attachment circuits (ACs) and AToM pseudowires (PWs) are checkpointed to the standby RP to provide NSF for AToM L2VPNs.

Checkpointing AToM Information

Checkpointing is a function that copies state information from the active RP to the backup RP, thereby ensuring that the backup RP has the latest information. If the active RP fails, the backup RP can take over.

For the AToM NSF feature, the checkpointing function copies the active RP's information bindings to the backup RP. The active RP sends updates to the backup RP when information is modified.

To display checkpointing data, issue the show acircuit checkpoint command on the active and backup RPs. The active and backup RPs have identical copies of the information.

Checkpointing Troubleshooting Tips

To help troubleshoot checkpointing errors, use the following commands:

•Use the debug acircuit checkpoint command to enable checkpointing debug messages for ACs.

•Use the debug mpls l2transport checkpoint command to enable checkpointing debug messages for AToM.

•Use the show acircuit checkpoint command to display the AC checkpoint information.

•Use the show mpls l2transport checkpoint command to display whether checkpointing is allowed, how many AToM VCs were bulk-synced (on the active RP), and how many AToM VCs have checkpoint data (on the standby RP).

•Use the show mpls l2transport vc detail command to display details of VC checkpointed information.

How to Configure AToM NSF

To configure AToM NSF, perform the following tasks:

•Configuring AToM (required)

•Configuring SSO on the Route Processors (required)

•Configuring Nonstop Forwarding on the Routers (required)

•Configuring MPLS LDP Graceful Restart (required)

•Verifying the Configuration (optional)

Configuring AToM

AToM virtual circuits (VCs) must be configured on the router. See the Any Transport over MPLS feature module for information on configuring AToM. For configuring L2VPN Interworking, see the L2VPN Interworking feature module.

Configuring SSO on the Route Processors

Route processors must be configured for SSO. See the Stateful Switchover feature module for configuration information.

Configuring Nonstop Forwarding on the Routers

You must enable Nonstop Forwarding on the routing protocols running between the P routers, PE routers, and CE routers. The routing protocols include OSPF, IS-IS, and BGP. See the Cisco Nonstop Forwarding feature module for configuration information.

Configuring MPLS LDP Graceful Restart

MPLS LDP Graceful Restart (GR) is enabled globally. When you enable LDP GR, it has no effect on existing LDP sessions. LDP GR is enabled for new sessions that are established after the feature has been globally enabled.

Perform this task to configure MPLS LDP GR.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip cef [distributed]

4. mpls ldp graceful-restart

5. interface type slot/port

6. mpls ip

7. mpls label protocol {ldp | tdp | both}

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 

ip cef [distributed]

Example:

Router(config)# ip cef distributed

Enables Cisco Express Forwarding.

Step 4  

mpls ldp graceful-restart
Example: 
Router (config)# mpls ldp graceful-restart

Enables the router to protect the LDP bindings and MPLS forwarding state during a disruption in service.

Step 5  

interface type slot/port
Example: 
Router(config)# interface pos 3/0

Specifies an interface and enters interface configuration mode.

Step 6 

mpls ip

Example:

Router(config-if)# mpls ip

Configures MPLS hop-by-hop forwarding for an interface.

Step 7 

mpls label protocol {ldp | tdp | both}

Example:

Router(config-if)# mpls label protocol ldp

Configures the use of LDP for an interface.

•You must use LDP, because TDP sessions are not supported.

You can also issue the mpls label protocol ldp command in global configuration mode, which enables LDP on all interfaces configured for MPLS.


Verifying the Configuration

The following commands help verify that AToM NSF has been configured correctly:

show mpls ldp neighbor with the graceful-restart keyword

Displays the Graceful Restart information for LDP sessions.

show mpls ldp graceful-restart

Displays Graceful Restart sessions and session parameters.


Configuration Examples for AToM NSF

This section provides the following configuration example:

•Ethernet to VLAN Interworking with AToM NSF: Example

Ethernet to VLAN Interworking with AToM NSF: Example

The following example shows how to configure AToM NSF on two PE routers.

PE1
PE2 
ip cef distributed

!

redundancy

mode sso

!

hw-module slot 2 image slot1:rsp-pv-mz

hw-module slot 3 image slot1:rsp-pv-mz

!

mpls ldp graceful-restart

mpls ip

mpls label protocol ldp

mpls ldp router-id Loopback0 force

mpls ldp advertise-tags

!

pseudowire-class atom-eth

 encapsulation mpls

 interworking ethernet

!

interface Loopback0

 ip address 10.8.8.8 255.255.255.255

!

interface FastEthernet1/1/0

 xconnect 10.9.9.9 123 encap mpls pw-class atom_eth


interface POS6/1/0

 ip address 10.1.1.1 255.255.255.0

 mpls ip

 mpls label protocol ldp

 clock source internal

 crc 32

!

interface Loopback0

 ip address 10.8.8.8 255.255.255.255

 no shutdown

!

router ospf 10

 nsf

 network 10.8.8.8 0.0.0.0 area 0

 network 19.1.1.1 0.0.0.0 area 0


ip cef distributed

!

redundancy

mode sso

!

hw-module slot 2 image slot1:rsp-pv-mz

hw-module slot 3 image slot1:rsp-pv-mz


mpls ldp graceful-restart

mpls ip

mpls label protocol ldp

mpls ldp router-id Loopback0 force

mpls ldp advertise-tags

!

pseudowire-class atom-eth

 encapsulation mpls

 interworking eth

!

interface Loopback0

 ip address 10.9.9.9 255.255.255.255

!

interface FastEthernet3/0/0

 ip route-cache cef

!

interface FastEthernet3/0/0.3

 encapsulation dot1Q 10

 xconnect 10.8.8.8 123 encap mpls pw-class atom_eth


interface POS1/0/0

 ip address 10.1.1.2 255.255.255.0

 mpls ip

 mpls label protocol ldp

 clock source internal

 crc 32

!

interface Loopback0

 ip address 10.9.9.9 255.255.255.255

!

router ospf 10

 nsf

 network 10.9.9.9 0.0.0.0 area 0

 network 10.1.1.2 0.0.0.0 area 0

Additional References

The following sections provide references related to AToM NSF.

Related Documents

Related Topic
Document Title

Stateful switchover

Stateful Switchover

MPLS Label Distribution Protocol

MPLS Label Distribution Protocol (LDP)

Cisco nonstop forwarding

Cisco Nonstop Forwarding

Any Transport over MPLS

Any Transport over MPLS

L2VPN Interworking configuration

L2VPN Interworking


Standards

Standards
Title

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

—


MIBs

MIBs
MIBs Link

MPLS Label Distribution Protocol MIB Version 8 Upgrade

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

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


RFCs

RFCs
Title

RFC 3036

LDP Specification

RFC 3478

Graceful Restart Mechanism for Label Distribution


Technical Assistance

Description
Link

The Cisco Technical Support & Documentation website contains thousands of 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/techsupport


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 High Availability Command Reference at http://www.cisco.com/en/US/docs/ios/ha/command/reference/ha_ 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.

•debug acircuit checkpoint

•debug mpls l2transport checkpoint

•show acircuit checkpoint

•show mpls l2transport checkpoint

•show mpls l2transport vc

Feature Information for AToM NSF

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. 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.

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

Table 1 Feature Information for AToM NSF 

Feature Name
Releases
Feature Information

AToM NSF

12.2(25)S
12.2(28)SB

This feature uses NSF, SSO, and Graceful Restart to allow a route processor to recover from a disruption in control plane service without losing its MPLS forwarding state.

In 12.2(25)S, this feature was introduced on the Cisco 7500 series router.

In 12.2(28)SB, this feature was integrated into the release.

The following sections provide information about this feature:

•Information About AToM NSF

•How to Configure AToM NSF



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

© 2007 Cisco Systems, Inc. All rights reserved.