Configuring Is-Is Nsr - HP FlexFabric 12900E Series Configuration Manual

•
GR restarter—Graceful restarting router. It must have GR capability.
•
GR helper—A neighbor of the GR restarter. It assists the GR restarter to complete the GR
process. By default, the device acts as the GR helper.
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
enter IS-IS view.
3. Enable IS-IS GR.
4. (Optional.) Suppress
the SA bit during
restart.
5. (Optional.)
Configure
timer.
6. (Optional.)
Configure
timer.
7. (Optional.)
Configure
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.
Command
system-view
IS-IS and
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
graceful-restart
graceful-restart suppress-sa
graceful-restart
the T1
count count
the T2
graceful-restart t2 seconds
the T3
graceful-restart t3 seconds
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.
t1 seconds 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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