- Read Me First
- MPLS LDP Graceful Restart
- NSF SSO--MPLS LDP and LDP Graceful Restart
- ISSU MPLS Clients
- MPLS Traffic Engineering--RSVP Graceful Restart
- NSF SSO--MPLS TE and RSVP Graceful Restart
- AToM Graceful Restart
- NSF SSO--Any Transport over MPLS and AToM Graceful Restart
- Configuring NSF SSO--MPLS VPN
- SSO and ISSU--MPLS VPN 6VPE and 6PE Support
- SSO Support for MPLS TE Autotunnel and Automesh
- MPLS Traffic Engineering Nonstop Routing Support
- NSR LDP Support
- Finding Feature Information
- Prerequisites for AToM Graceful Restart
- Restrictions for AToM Graceful Restart
- Information About AToM Graceful Restart
- How to Configure AToM Graceful Restart
- Configuration Examples for AToM Graceful Restart
- Additional References
- Feature Information for AToM Graceful Restart
AToM Graceful Restart
The AToM Graceful Restart feature assists neighboring devices that have nonstop forwarding (NSF), stateful switchover (SSO), and graceful restart (GR) for Any Transport over Multiprotocol Label Switching (AToM) to recover gracefully from an interruption in service. AToM GR functions strictly in helper mode, which means it helps other devices that are enabled with the NSF/SSO—Any Transport over MPLS and AToM Graceful Restart feature to recover. If the device with AToM GR fails, its peers cannot help it recover. AToM GR is based on the MPLS Label Distribution Protocol (LDP) Graceful Restart feature.
Keep the following points in mind when reading this document:
- Finding Feature Information
- Prerequisites for AToM Graceful Restart
- Restrictions for AToM Graceful Restart
- Information About AToM Graceful Restart
- How to Configure AToM Graceful Restart
- Configuration Examples for AToM Graceful Restart
- Additional References
- Feature Information for AToM Graceful Restart
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 at the end of this module.
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.
Prerequisites for AToM Graceful Restart
Any Transport over Multiprotocol Label Switching (AToM) must be configured.
Restrictions for AToM Graceful Restart
Any Transport over Multiprotocol Label Switching (AToM) graceful restart (GR) is supported in strict helper mode.
MPLS Label Distribution Protocol (LDP) GR cannot be configured on label-controlled ATM (LC-ATM) interfaces.
On some hardware platforms, Tag Distribution Protocol (TDP) sessions are not supported. Only LDP sessions are supported.
Information About AToM Graceful Restart
How AToM Graceful Restart Works
Any Transport over Multiprotocol Label Switching Graceful Restart (AToM GR) works in strict helper mode, which means it helps a neighboring Route Processor (RP) that has AToM nonstop forwarding (NSF) and stateful switchover (SSO) to recover from a disruption in service without losing its MPLS forwarding state. The disruption in service could result from a TCP or User Datagram Protocol (UDP) event or the SSO of an RP. AToM GR is based on the MPLS Label Distribution Protocol (LDP) Graceful Restart feature, which preserves forwarding information for AToM circuits during an LDP session interruption. When the neighboring device establishes a new session, the LDP bindings and MPLS forwarding state are recovered.
How to Configure AToM Graceful Restart
Configuring AToM Graceful Restart
There is no Any Transport over Multiprotocol Label Switching (AToM)-specific configuration for AToM Graceful Restart (GR). You enable the Label Distribution Protocol (LDP) GR to assist a neighboring device configured with AToM nonstop forwarding (NSF) and stateful switchover (SSO) to maintain its forwarding state while the LDP session is disrupted.
1.
enable
2.
configure terminal
3.
ip cef distributed
4.
mpls ldp graceful-restart
5.
exit
6.
show mpls l2transport vc detail
DETAILED STEPS
Configuration Examples for AToM Graceful Restart
- Example: Configuring AToM Graceful Restart
- Examples: Verifying AToM Graceful Restart Recovery from an LDP Session Disruption
Example: Configuring AToM Graceful Restart
The following example shows a Fast Ethernet VLAN over Multiprotocol Label Switching (MPLS) configuration. PE1 is configured with Any Transport over MPLS Graceful Restart (AToM GR). PE2 is configured with AToM nonstop forwarding (NSF) and stateful switchover (SSO). The commands for configuring AToM GR and NSF/SSO are shown in bold.
PE1 with AToM GR |
PE2 with AToM NSF/SSO |
---|---|
ip cef distributed ! mpls label protocol ldp mpls ldp graceful-restart mpls ldp router-id Loopback0 ! pseudowire-class atom encapsulation mpls ! interface Loopback0 ip address 10.1.1.2 255.255.255.255 ! interface FastEthernet2/1/1 no ip address ! interface FastEthernet2/1/1.2 description “xconnect to PE2” encapsulation dot1Q 2 native xconnect 10.2.2.2 1002 pw-class mpls ! ! IGP for MPLS router ospf 10 log-adjacency-changes auto-cost reference-bandwidth 1000 network 10.1.1.2 10.0.0.0 area 0 network 10.1.1.0 10.0.0.255 area 0 |
redundancy mode sso ip cef distributed ! mpls label protocol ldp mpls ldp graceful-restart mpls ldp router-id Loopback0 ! pseudowire-class atom encapsulation mpls ! interface Loopback0 ip address 10.2.2.2 255.255.255.255 ! interface FastEthernet0/3/2 no ip address ! interface FastEthernet0/3/2.2 description “xconnect to PE1” encapsulation dot1Q 2 xconnect 10.1.1.2 1002 pw-class mpls ! ! IGP for MPLS router ospf 10 log-adjacency-changes nsf cisco enforce global auto-cost reference-bandwidth 1000 network 10.2.2.2 10.0.0.0 area 0 network 10.1.1.0 10.0.0.255 area 0 |
Examples: Verifying AToM Graceful Restart Recovery from an LDP Session Disruption
The following examples show the output of the show mpls l2transport vc command during normal operation and when a Label Distribution Protocol (LDP) session is recovering from a disruption.
The following example shows the status of the virtual circuit (VC) on PE1 with Any Transport over Multiprotocol Label Switching Graceful Restart (AToM GR) during normal operation:
Device# show mpls l2transport vc Local intf Local circuit Dest address VC ID Status ------------- -------------------- --------------- ---------- ---------- Fa2/1/1.2 Eth VLAN 2 10.2.2.2 1002 UP
The following example shows the status of the VC on PE1 with AToM GR while the VC is recovering from an LDP session disruption. The forwarding state for the circuit remains as it was before the disruption.
Device# show mpls l2transport vc Local intf Local circuit Dest address VC ID Status ------------- -------------------- --------------- ---------- ---------- Fa2/1/1.2 Eth VLAN 2 10.2.2.2 1002 RECOVERING
The following example shows the status of the VC on PE1 with AToM GR after the LDP session disruption was cleared. The AToM label bindings were advertised within the allotted time and the status returned to UP.
Device# show mpls l2transport vc Local intf Local circuit Dest address VC ID Status ------------- -------------------- --------------- ---------- ---------- Fa2/1/1.2 Eth VLAN 2 10.2.2.2 1002 UP
The following example shows the detailed status of the VC on PE1 with AToM GR during normal operation:
Device# show mpls l2transport vc detail Local interface: Fa2/1/1.2 up, line protocol up, Eth VLAN 2 up Destination address: 10.2.2.2, VC ID: 1002, VC status: up Preferred path: not configured Default path: active Tunnel label: imp-null, next hop point2point Output interface: Se2/0/2, imposed label stack {16} Create time: 1d00h, last status change time: 1d00h Signaling protocol: LDP, peer 10.2.2.2:0 up MPLS VC labels: local 21, remote 16 Group ID: local 0, remote 0 MTU: local 1500, remote 1500 Remote interface description: "xconnect to PE2" Sequencing: receive disabled, send disabled VC statistics: packet totals: receive 3466, send 12286 byte totals: receive 4322368, send 5040220 packet drops: receive 0, send 0
The following example shows the detailed status of the VC on PE1 with AToM GR while the VC is recovering.
Device# show mpls l2transport vc detail Local interface: Fa2/1/1.2 up, line protocol up, Eth VLAN 2 up Destination address: 10.2.2.2, VC ID: 1002, VC status: recovering Preferred path: not configured Default path: active Tunnel label: imp-null, next hop point2point Output interface: Se2/0/2, imposed label stack {16} Create time: 1d00h, last status change time: 00:00:03 Signaling protocol: LDP, peer 10.2.2.2:0 down MPLS VC labels: local 21, remote 16 Group ID: local 0, remote 0 MTU: local 1500, remote 1500 Remote interface description: "xconnect to PE2" Sequencing: receive disabled, send disabled VC statistics: packet totals: receive 20040, send 28879 byte totals: receive 25073016, send 25992388 packet drops: receive 0, send 0
Additional References
Related Documents
Related Topic |
Document Title |
---|---|
Cisco IOS commands |
|
MPLS AToM and LDP commands |
|
MPLS LDP graceful restart |
“MPLS LDP Graceful Restart” module in the MPLS: High Availability Configuration Guide (part of the Multiprotocol Label Switching Configuration Guide Library) |
Configuring AToM |
“Any Transport over MPLS” module in the MPLS: Layer 2 VPNs Configuration Guide (part of the Multiprotocol Label Switching Configuration Guide Library) |
Nonstop forwarding and stateful switchover for AToM |
“NSF SSO Any Transport over MPLS and AToM Graceful Restart” module in the MPLS: High Availability Configuration Guide (part of the Multiprotocol Label Switching Configuration Guide Library) |
High availability commands |
Cisco IOS High Availability Command Reference |
MIBs
MIBs |
MIBs Link |
---|---|
MPLS Label Distribution Protocol MIB Version 8 Upgrade |
To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
RFCs |
Title |
---|---|
RFC 3036 |
LDP Specification |
RFC 3478 |
Graceful Restart Mechanism for Label Distribution |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for AToM Graceful Restart
The following table provides release information about the feature or features described in this module. This table 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.
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.Feature Name |
Releases |
Feature Information |
---|---|---|
AToM Graceful Restart |
12.0(29)S 12.2(33)SRA 12.2(33)SXH 12.4(11)T Cisco IOS XE Release 2.3 |
The AToM Graceful Restart feature assists neighboring devices that have nonstop forwarding (NSF), stateful switchover (SSO), and graceful restart (GR) for Any Transport over Multiprotocol Label Switching (AToM) to recover gracefully from an interruption in service. AToM GR functions strictly in helper mode, which means it helps other devices that are enabled with the NSF/SSO—Any Transport over MPLS and AToM Graceful Restart feature to recover. If the device with AToM GR fails, its peers cannot help it recover. AToM GR is based on the MPLS Label Distribution Protocol (LDP) Graceful Restart feature. In Cisco IOS Release 12.0(29)S, this feature was introduced. In Cisco IOS Release 12.2(33)SRA, support was added for the Cisco 7600 series routers. In Cisco IOS Release 12.2(33)SXH, this feature was integrated into the release. In Cisco IOS Release 12.4(11)T, this feature was integrated into the release. In Cisco IOS Release XE 2.3, this feature was implemented on the Cisco ASR 1000 Series Aggregation Services Routers. This feature uses no new or modified commands. |