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Configure IS-IS GR on the GR restarter.
GR restarter uses the following timers:
•
T1 timer—Specifies the times that GR restarter can send a Restart TLV with the RR bit set.
When rebooted, the GR restarter sends a Restart TLV with the RR bit set to its neighbor. If the
GR restarter receives a Restart TLV with the RA set from its neighbor before the T1 timer
expires, the GR process starts. Otherwise, the GR process fails.
•
T2 timer—Specifies the LSDB synchronization interval. Each LSDB has a T2 timer. The
Level-1-2 router has a Level-1 timer and a Level-2 timer. If the LSDBs have not synchronized
before the two timers expire, the GR process fails.
•
T3 timer—Specifies the GR interval. The GR interval is set as the holdtime in hello PDUs.
Within the interval, the neighbors maintain their adjacency with the GR restarter. If the GR
process has not completed within the holdtime, the neighbors tear down the neighbor
relationship and the GR process fails.
IMPORTANT:
IS-IS GR and IS-IS NSR are mutually exclusive. Do not configure them at the same time.
To configure GR on the GR restarter:
Step
1.
Enter system view.
2.
Enable IS-IS and enter IS-IS
view.
3.
Enable IS-IS GR.
4.
(Optional.) Suppress the SA
bit during restart.
5.
(Optional.) Configure the T1
timer.
6.
(Optional.) Configure the T2
timer.
7.
(Optional.) Configure the T3
timer.
Configuring IS-IS NSR
After an active/standby switchover, the GR restarter obtains routing information from its neighbors,
and the IS-IS process must learn all the routes. If the network topology changes during the
switchover, removed routes cannot be updated to the device, which can result in blackhole routes.
NSR solves the problem by backing up IS-IS link state information from the active process to the
standby process. After an active/standby switchover, NSR can complete link state recovery and
route regeneration without requiring the cooperation of other devices.
Command
system-view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
graceful-restart
graceful-restart suppress-sa
graceful-restart t1 seconds count
count
graceful-restart t2 seconds
graceful-restart t3 seconds
164
Remarks
N/A
N/A
By default, the GR capability for
IS-IS is disabled.
By default, the SA bit is not
suppressed.
By enabling the GR restarter to
suppress the
Suppress-Advertisement (SA)
bit in the hello PDUs, the
neighbors will still advertise their
adjacency with the GR restarter.
By default, the T1 timer is 3
seconds and can expire 10
times.
By default, the T2 timer is 60
seconds.
By default, the T2 timer is 300
seconds.
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Troubleshooting
