EIGRP IPv6 NSFGR
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EIGRP IPv6 NSF/GR

Last Updated: July 26, 2012

The EIGRP IPv6 Nonstop Forwarding (NSF)/Graceful Restart (GR) feature allows an NSF-aware device that is running the Enhanced Interior Gateway Routing Protocol (EIGRP) to forward IPv6 packets while the EIGRP restarts after recovering from a failure.

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 EIGRP IPv6 NSF/GR

  • EIGRP IPv6 should be configured on the devices. You need not specify the network network-number command in EIGRP named mode. By default, EIGRP IPv6 enables EIGRP on all interfaces configured with an IPv6.
  • A Cisco software that supports NSF awareness or NSF capabilities must be installed.
  • Redundant facility must be configured to notify EIGRP during switchover and to notify whether the restart is due to switchover or a device reboot.
  • An NSF-aware device must be up and completely converged with the network before it can assist an NSF-capable device in an NSF restart operation.
  • All neighboring devices participating in EIGRP NSF must be NSF-capable or NSF-aware.

Restrictions for EIGRP IPv6 NSF/GR

  • NSF is supported on platforms that support High Availability (HA) systems.
  • An EIGRP NSF-aware network does not allow two neighbors to perform an NSF restart operation at the same time. However, the neighbors will reestablish peering sessions after the NSF restart operation is complete.
  • NSF for IPv6 is supported only in EIGRP named mode configurations.

Information About EIGRP IPv6 NSF/GR

EIGRP IPv6 NSF/GR

The EIGRP IPv6 NSF/GR feature allows an NSF-aware device that is running EIGRP to forward IPv6 packets along the routes that are known to a device that is performing the switchover operation or if the device is in a failure mode. EIGRP peers retain the adjacency and the route learned from the restarting peer, and the EIGRP peers continue to forward IPv6 packets to the restarting peer. The HA systems retain the forwarding table and continue to forward IPv6 packets until the control plane (EIGRP) has converged on the restarting device.

NSF allows forwarding of IPv6 packets while the control plane restarts after recovering from a failure. Graceful Restart (GR) allows topology databases to resynchronize while maintaining neighbor relationships and forwarding paths.


Note
NSF supports IPv4 in EIGRP classic mode and named mode configurations. NSF supports IPv6 in named mode. For more information about the EIGRP IPv4 NSF feature, see the "EIGRP Nonstop Forwarding Awareness" module in the IP Routing: EIGRP Configuration Guide.

EIGRP IPv6 NSF Timers

NSF/GR supports three types of timers: the signal timer, the converge timer, and the graceful-restart purge-time timer.

The signal timer can be configured to adjust the maximum time of the initial restart period, where the restarting device sends hello packets with the restart (RS) bit set. When the timer expires, if the restarting device has not learned about any neighbor or any NSF-aware neighbor or has not received all the updates from the neighbors, the routing information base (RIB) is notified for convergence. The default value for the signal timer is 20 seconds. The timers nsf signal command is used to configure the signal timer.

The converge timer can be configured to adjust the maximum time the restarting device waits for the end-of-table (EOT) indications from all neighbors. The default value for the converge timer is 120 seconds. The timers nsf converge command is used to configure the converge timer.

The graceful-restart purge-time timer can be configured to adjust the maximum waiting time to receive the convergent signal from the restarting device. The graceful-restart purge-time timer is used when the NSF-aware peer does not receive the EOT indication from the restarting neighbor. When the graceful-restart purge-time timer expires, the EIGRP peer scans the topology table for the stale routes from the restarting neighbor and changes the stale routes to active, thereby allowing EIGRP peers to find alternate routes instead of waiting during a long switchover operation. The default value for the graceful-restart purge-time timer is 240 seconds. The timers graceful-restart purge-time command is used to configure the graceful-restart purge-time timer.

How to Configure EIGRP IPv6 NSF/GR

Enabling EIGRP IPv6 NSF/GR

SUMMARY STEPS

1.    enable

2.   configure terminal

3.   router eigrp name

4.   address-family ipv6 autonomous-system number

5.   nsf

6.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 
 Enters global configuration mode.  
Step 3
router eigrp name


Example:

Device(config)# router eigrp e1

 
 Configures an EIGRP routing process and enters router configuration mode.  
Step 4
address-family ipv6 autonomous-system number


Example:

Device(config-router)# address-family ipv6 autonomous-system 1

 
 Enters address family configuration mode to configure an EIGRP IPv6 routing instance.  
Step 5
nsf


Example:

Device(config-router-af)# nsf

 
 Enables NSF for the specific address family on the device.  
Step 6
end


Example:

Device(config-router-af)# end

 
 Exits address family configuration mode and returns to privileged EXEC mode.  

Modifying EIGRP IPv6 NSF Timers

Perform this task to modify EIGRP IPv6 NSF timers. This task is optional.

SUMMARY STEPS

1.    enable

2.   configure terminal

3.   router eigrp name

4.   address-family ipv6 autonomous-system number

5.   timers nsf signal seconds

6.   timers nsf converge seconds

7.   timers graceful-restart purge-time seconds

8.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
router eigrp name


Example:

Device(config)# router eigrp e1

 

Configures an EIGRP routing process and enters router configuration mode.

 
Step 4
address-family ipv6 autonomous-system number


Example:

Device(config-router)# address-family ipv6 autonomous-system 1

 

Enters address family configuration mode to configure an EIGRP IPv6 routing instance.

 
Step 5
timers nsf signal seconds


Example:

Device(config-router-af)# timers nsf signal 15

 

Sets the initial restart period, in seconds, for the restarting device to send hello packets with the RS bit set. The default is 20.

 
Step 6
timers nsf converge seconds


Example:

Device(config-router-af)# timers nsf converge 60

 

Sets the maximum time, in seconds, that the restarting device must wait for end-of-table (EOT) indications from all neighbors. The default is 120.

 
Step 7
timers graceful-restart purge-time seconds


Example:

Device(config-router-af)# timers graceful-restart purge-time 150

 

Sets the graceful-restart purge-time timer to determine the period, in seconds, for which an NSF-aware device that is running EIGRP must hold routes for an inactive peer. The default is 240.

 
Step 8
end


Example:

Device(config-router-af)# end

 

Exits address family configuration mode and returns to privileged EXEC mode.

 

Verifying the EIGRP IPv6 NSF/GR Configuration

Perform this task to verify the configuration of EIGRP IPv6 NSF/GR on an NSF-aware device.

SUMMARY STEPS

1.    enable

2.   show ipv6 protocols


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
show ipv6 protocols


Example:

Device# show ipv6 protocols

 
 Displays the parameters and the current state of the active IPv6 routing protocol process. The output of this command can be used to verify the EIGRP IPv6 NSF/GR configuration.  

Monitoring EIGRP IPv6 NSF/GR Events

Perform this task to monitor EIGRP IPv6 NSF/GR debug events and notifications on an NSF-aware router.

SUMMARY STEPS

1.    enable

2.   debug eigrp nsf

3.   debug eigrp address-family ipv6 notifications


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
debug eigrp nsf


Example:

Device# debug eigrp nsf

 
 Displays debugging information about NSF events on the console of the router.  
Step 3
debug eigrp address-family ipv6 notifications


Example:

Device# debug eigrp address-family ipv6 notifications

 
 Displays debugging information about EIGRP address family IPv6 event notifications.  

Configuration Examples for EIGRP IPv6 NSF/GR

Example: Configuring an EIGRP NSF Converge Timer

The following example shows how to adjust the maximum time the restarting router waits for EOT indications from all neighbors: 

Device> enable
Device# configure terminal
Device(config)# router eigrp name
Device(config-router)# address-family ipv6 autonomous system 1
Device(config-router-af)# timers nsf converge 60
Device(config-router-af)# end

Example: Verifying the Configuration of EIGRP IPv6 NSF/GR on an NSF-Aware Device

The following is sample output from the show ipv6 protocols command, which shows that EIGRP NSF is enabled, the graceful-restart purge-time timer is set to 260 seconds, the signal timer is set to 15 seconds, and the converge timer is set to 65 seconds: 

Device> enable
Device# show ipv6 protocols

IPv6 Routing Protocol is "connected"
IPv6 Routing Protocol is "bgp 1"
  IGP synchronization is disabled
  Redistribution:
    None
IPv6 Routing Protocol is "bgp multicast"
IPv6 Routing Protocol is "ND"
IPv6 Routing Protocol is "eigrp 1"
EIGRP-IPv6 VR(name) Address-Family Protocol for AS(1)
  Metric weight K1=1, K2=0, K3=1, K4=0, K5=0 K6=0
  Metric rib-scale 128
  Metric version 64bit
  NSF-aware route hold timer is 260
  EIGRP NSF enabled
     NSF signal timer is 15s
     NSF converge timer is 65s
  Router-ID: 10.1.1.1
  Topology : 0 (base) 
    Active Timer: 3 min
    Distance: internal 90 external 170
    Maximum path: 16
    Maximum hopcount 100
    Maximum metric variance 1
    Total Prefix Count: 0
    Total Redist Count: 0

  Interfaces:
  Redistribution:
    None

Additional References

Related Documents

Related Topic Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Cisco Express Forwarding (formerly known as CEF) commands

IP Switching Command Reference

EIGRP commands

IP Routing: EIGRP Command Reference

Nonstop forwarding (NSF)

  • "Cisco Nonstop Forwarding" module in the Stateful Switchover Deployment Guide
  • "Cisco Nonstop Forwarding" module in the High Availability Configuration Guide
  • "EIGRP Nonstop Forwarding Awareness" module in the IP Routing: EIGRP Configuration Guide

Command Lookup Tool

http://tools.cisco.com/Support/CLILookup

Standards and RFCs

Standard/RFC Title

RFC 4724

Graceful Restart Mechanism for BGP

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.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for EIGRP IPv6 NSF/GR

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.

Table 1Feature Information for EIGRP IPv6 NSF/GR

Feature Name

Releases

Feature Information

EIGRP IPv6 NSF/GR

15.2(2)S

The EIGRP IPv6 NSF/GR feature allows an NSF-aware router that is running EIGRP to forward IPv6 packets while the control plane restarts after recovering from a failure.

The following commands were introduced or modified: debug eigrp nsf, nsf, show ipv6 protocols, timers graceful-restart purge-time, timers nsf converge, timers nsf signal.

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

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

© 2012 Cisco Systems, Inc. All rights reserved.