-
- MPLS Traffic Engineering - LSP Attributes
- MPLS Traffic Engineering (TE) - Autotunnel Primary and Backup
- MPLS Traffic Engineering - AutoTunnel Mesh Groups
- MPLS Traffic Engineering - Verbatim Path Support
- MPLS Traffic Engineering - RSVP Hello State Timer
- MPLS Traffic Engineering Forwarding Adjacency
- MPLS Traffic Engineering (TE) - Class-based Tunnel Selection
- MPLS Traffic Engineering - Interarea Tunnels
- MPLS TE - Bundled Interface Support
- MPLS Traffic Engineering�Automatic Bandwidth Adjustment for TE Tunnels
- MPLS Point-to-Multipoint Traffic Engineering
- MPLS Traffic Engineering�Tunnel Source
-
- MPLS Traffic Engineering - Inter-AS TE
- MPLS Traffic Engineering - Shared Risk Link Groups
- MPLS Traffic Engineering (TE) - Autotunnel Primary and Backup
- MPLS Traffic Engineering (TE) - Path Protection
- MPLS Traffic Engineering (TE) - Fast Reroute (FRR) Link and Node Protection
- MPLS TE: Link and Node Protection, with RSVP Hellos Support (with Fast Tunnel Interface Down Detection)
- MPLS Traffic Engineering: BFD-triggered Fast Reroute (FRR)
-
- MPLS MTU Command Changes
- AToM Static Pseudowire Provisioning
- MPLS Pseudowire Status Signaling
- L2VPN Interworking
- L2VPN Pseudowire Redundancy
- L2VPN Pseudowire Switching
- VPLS Autodiscovery: BGP Based
- H-VPLS N-PE Redundancy for QinQ and MPLS Access
- L2VPN Multisegment Pseudowires
- QOS Policy Support on L2VPN ATM PVPs
- L2VPN: Pseudowire Preferential Forwarding
-
- Configuring MPLS Layer 3 VPNs
- MPLS VPN Half-Duplex VRF
- MPLS VPN�Show Running VRF
- MPLS VPN�VRF CLI for IPv4 and IPv6 VPNs
- MPLS VPN--BGP Local Convergence
- MPLS VPN�Route Target Rewrite
- MPLS VPN�Per VRF Label
- MPLS VPN 6VPE per VRF Label
- MPLS Multi-VRF (VRF Lite) Support
- BGP Best External
- BGP PIC Edge for IP and MPLS-VPN
- MPLS VPN - L3VPN over GRE
- Dynamic Layer-3 VPNs with Multipoint GRE Tunnels
- MPLS VPN over mGRE
-
- MPLS LSP Ping/Traceroute for LDP/TE, and LSP Ping for VCCV
- MPLS EM�MPLS LSP Multipath Tree Trace
- Pseudowire Emulation Edge-to-Edge MIBs for Ethernet, Frame Relay, and ATM Services
- MPLS Enhancements to Interfaces MIB
- MPLS Label Distribution Protocol MIB Version 8 Upgrade
- MPLS EM�MPLS LDP MIB - RFC 3815
- MPLS Label Switching Router MIB
- MPLS EM�MPLS LSR MIB - RFC 3813
- MPLS Traffic Engineering MIB
- MPLS Traffic Engineering - Fast Reroute MIB
- MPLS EM - TE MIB RFC 3812
- MPLS VPN�MIB Support
- MPLS EM - MPLS VPN MIB RFC4382 Upgrade
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- MPLS High Availability: Overview
- MPLS High Availability: Command Changes
- MPLS LDP Graceful Restart
- NSF/SSO - MPLS LDP and LDP Graceful Restart
- NSF/SSO: MPLS VPN
- AToM Graceful Restart
- NSF/SSO�Any Transport over MPLS and AToM Graceful Restart
- NSF/SSO - MPLS TE and RSVP Graceful Restart
- ISSU MPLS Clients
- NSF/SSO/ISSU Support for VPLS
- NSF/SSO and ISSU - MPLS VPN 6VPE and 6PE
NSF/SSO—Any Transport over MPLS and AToM Graceful Restart
The NSF/SSO—Any Transport over MPLS and AToM Graceful Restart feature allows Any Transport over MPLS (AToM) to use Cisco nonstop forwarding (NSF), stateful switchover (SSO), and Graceful Restart (GR) to facilitate a Route Processor (RP) to recover from a disruption in control plane service without losing its Multiprotocol Label Switching (MPLS) forwarding state.
NSF with SSO is effective at increasing the 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 the control plane service during a critical failure in the primary processor. SSO synchronizes the network state information between the primary and the secondary processor.

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
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 AToM NSF" section.
Use Cisco Feature Navigator to find information about platform support and Cisco 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
•Configuration Examples for AToM NSF
•Feature Information for AToM NSF
Prerequisites for AToM NSF
Before you configure AToM NSF, ensure the following tasks are completed:
•AToM virtual circuits (VCs) are configured on the router. For information on configuring AToM, see the Any Transport over MPLS feature module. For configuring L2VPN Interworking, see the L2VPN Interworking feature module.
•SSO is configured on the Route Processors. For configuration information, see the Stateful Switchover feature module.
•Nonstop forwarding is configured on the routers. You must enable nonstop forwarding on the routing protocols running between the provider edge (PE) and customer edge (CE) routers. The routing protocols are Open Shortest Path First (OSPF), Intermediate System-to-Intermediate System (IS-IS), and Border Gateway Protocol (BGP). For configuring nonstop forwarding, see the
Cisco Nonstop Forwarding feature module.
•The routers must be configured to detect and interact with the neighbor routers in the MPLS high availibility (HA) environment. AToM NSF requires that neighbor networking devices be able to perform AToM GR. In Cisco IOS Releases 12.2(25)S and 12.2(28)SB, the Cisco 7200 and Cisco 7500 routers support AToM GR and can be used as neighbor networking devices. In Cisco IOS Release 12.2(33)SRC, the Cisco 7600 routers support AToM high availability HA and MPLS Label Distribution Protocol (LDP) GR.
•The Route Processors for SSO and GR are configured. For more information, see the Stateful Switchover feature module.
•NSF on the routing protocols running between the PE, and CE routers must be enabled. The routing protocols are as follows:
–BGP
–IS-IS
–OSPF
For more information, see the Cisco Nonstop Forwarding feature module.
Supported Hardware
For hardware requirements for this feature, see the following documents:
•For Cisco IOS Release 12.2(25)S, see the "Supported Hardware" section of the Cross-Platform Release Notes for Cisco IOS Release 12.2S.
•For Cisco IOS Release 12.2(28)SB, see the "Supported Hardware" section of the Cross-Platform Release Notes for Cisco IOS Release 12.2SB.
•For Cisco IOS Release 12.2(33)SRC, see the "Supported Hardware" section of the Release Notes for Cisco IOS Release 12.2SR for the Cisco 7600 Series Routers.
Restrictions for AToM NSF
•Tag Distribution Protocol (TDP) sessions are not supported. Only LDP sessions are supported.
•AToM NSF cannot be configured on label-controlled ATM (LC-ATM) interfaces.
•AToM NSF does not support Layer 2 Tunnel Protocol Version 3 (L2TPv3) Interworking; only AToM Layer 2 Virtual Private Network (L2VPN) Interworking is supported.
•AToM NSF interoperates with Layer 2 local switching. However, AToM NSF has no effect on interfaces configured for local switching.
•You must disable fair queueing on serial interfaces to allow distributed Cisco Express Forwarding to work on the interfaces.
•On Cisco 7500 series routers, distributed Cisco Express Forwarding is needed to support AToM NSF.
•The Cisco 7500 router does not support AToM Ethernet-VLAN interworking IP; however, AToM Ethernet-VLAN interworking Ethernet is supported.
Information About AToM NSF
•AToM Information Checkpointing
How AToM NSF Works
AToM NSF improves the availability of the network of the service provider that uses AToM to provide Layer 2 VPN services. 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.
AToM Information Checkpointing
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 the copying of state information.
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, use 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 debug vfi checkpoint command to debug virtual forwarding instance (VFI) checkpointing events and errors.
•Use the show acircuit checkpoint command to display AC checkpoint information.
•Use the show mpls l2transport checkpoint command to display whether checkpointing is allowed, how many AToM VCs were bulk-synchronized (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.
•Use the show vfi checkpoint command to display checkpointing information on a VFI.
ISSU Support
Beginning with Cisco IOS Release 12.2(33)SRC, AToM NSF supports the In Service Software Upgrade (ISSU) capability. Virtual Private LAN Services (VPLS) NSF/SSO and HA with ISSU work together to enable upgrades or downgrades of a Cisco IOS image without control and data plane outages. With ISSU, all message data structures that are used for checkpointing and exchanges between the active RP and standby RP are versioned.
The maximum transmission length (MTU) of checkpoint messages can be negotiated. The VPLS ISSU client transforms checkpoint messages by converting Source Specific Multicast (SSM) IDs and VFI IDs of an individual VFI to AC and PW, respectively.
Configuring MPLS LDP Graceful Restart
Before you configure AToM NSF, you need to configure MPLS LDP Graceful Restart.
MPLS LDP 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}
8. exit
DETAILED STEPS
Configuration Examples for AToM NSF
•Example: Ethernet to VLAN Interworking with AToM NSF
Example: Ethernet to VLAN Interworking with AToM NSF
The following example shows how to configure AToM NSF on two PE routers:
Additional References
Related Documents
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Cisco IOS commands |
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Cisco IOS Multiprotocol Label Switching Command Reference |
Cisco IOS Multiprotocol Label Switching Command Reference |
Stateful switchover |
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MPLS Label Distribution Protocol |
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Cisco nonstop forwarding |
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Any Transport over MPLS |
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L2VPN Interworking configuration |
Standards
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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MIBs
RFCs
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RFC 3036 |
LDP Specification |
RFC 3478 |
Graceful Restart Mechanism for Label Distribution |
Technical Assistance
Feature Information for AToM NSF
Table 1 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.