The EIGRP IPv6 NSF/GR feature allows a Nonstop Forwarding (NSF)-aware device that is running Enhanced Interior Gateway Routing Protocol (EIGRP) to forward IPv6 packets while EIGRP restarts after recovering from a failure.
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Prerequisites for EIGRP IPv6 NSF/GR
EIGRP (Enhanced Interior Gateway Routing Protocol) IPv6 must be configured on devices. You need not specify the
networknetwork-number command in EIGRP named mode. By default, EIGRP IPv6 enables EIGRP on all interfaces configured with an IPv6 address.
Cisco software that supports Nonstop Forwarding (NSF) awareness or NSF capabilities must be installed.
A redundant facility must be configured to notify EIGRP during a switchover and to notify whether the restart is due to a 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
Nonstop Forwarding (NSF) is supported on platforms that support high-availability systems.
An Enhanced Interior Gateway Routing Protocol (EIGRP) NSF-aware network does not allow two neighbors to perform an NSF restart operation at the same time. However, neighbors can re-establish 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 a Nonstop Forwarding (NSF)-aware device that is running Enhanced Interior Gateway Routing Protocol (EIGRP) to forward IPv6 packets along routes that are known to a device that is performing a switchover operation. EIGRP peers retain adjacencies and routes learned from a restarting peer (the device that is undergoing a switchover), and the EIGRP peers continue to forward IPv6 packets to the restarting peer. The high-availability systems on the device 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 device restarts after a failure. Graceful Restart (GR) allows topology databases to resynchronize while maintaining neighbor relationships and forwarding paths.
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
The EIGRP IPv6 NSF/GR feature supports three types of timers: the signal timer, the converge timer, and the graceful-restart purge-time timer.
Configure the signal timer to adjust the maximum time of the initial restart period. The restarting device sends hello packets with the restart-signal (RS) bit set. If the restarting device has not learned about any neighbor or any Nonstop Forwarding (NSF)-aware neighbor or has not received all updates from neighbors when the timer expires, the Routing Information Base (RIB) is notified for convergence. The default value for the signal timer is 20 seconds. The
timersnsfsignal command is used to configure the signal timer.
Configure the converge timer to adjust the maximum time that a restarting device waits for the end-of-table (EOT) indications from all neighbors. The default value for the converge timer is 120 seconds. The
timersnsfconverge command is used to configure the converge timer.
Configure the graceful-restart purge-time timer to adjust the maximum waiting time to receive the convergent signal from a 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 Enhanced Interior Gateway Routing Protocol (EIGRP) peer scans the topology table for stale routes from the restarting neighbor and changes the stale routes to active. This process allows 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
timersgraceful-restartpurge-time command is used to configure the graceful-restart purge-time timer.
How to Configure EIGRP IPv6 NSF/GR
Enabling EIGRP IPv6 NSF/GR
Command or Action
Enables privileged EXEC mode.
Enter your password if prompted.
Device# configure terminal
Enters global configuration mode.
Device(config)# router eigrp e1
Configures an Enhanced Interior Gateway Routing Protocol (EIGRP) routing process and enters router configuration mode.
Displays debugging information about Enhanced Interior Gateway Routing Protocol (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 that the restarting router waits for end-of-table (EOT) indications from all neighbors:
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
Example: Verifying the Configuration of EIGRP IPv6 NSF/GR on an NSF-Aware Device
The following is a sample output from the
showipv6protocols 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# show ipv6 protocols
IPv6 Routing Protocol is "connected"
IPv6 Routing Protocol is "bgp 1"
IGP synchronization is disabled
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
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
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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.
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Table 1 Feature Information for EIGRP
Cisco IOS XE Release 3.6S
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.
commands were introduced or modified: