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•
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.
NOTE:
An active/standby switchover cannot trigger GR on the VSR1000 router.
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 two T2 timers: 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.
To configure GR on the GR restarter:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable IS-IS and
enter IS-IS view.
isis
[
process-id
] [
vpn-instance
vpn-instance-name
]
N/A
3.
Enable IS-IS GR.
graceful-restart
By default, the GR capability for IS-IS is
disabled.
4.
(Optional.) Suppress
the SA bit during
restart.
graceful-restart suppress-sa
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.
5.
(Optional.) Configure
the T1 timer.
graceful-restart t1
seconds
count
count
By default, the T1 timer is 3 seconds and can
expire 10 times.
6.
(Optional.) Configure
the T2 timer.
graceful-restart t2
seconds
By default, the T2 timer is 60 seconds.
7.
(Optional.) Configure
the T3 timer.
graceful-restart t3
seconds
By default, the T2 timer is 300 seconds.
Configuring BFD for IS-IS
BFD provides a single mechanism to quickly detect and monitor the connectivity of links between OSPF
neighbors, reducing network convergence time. For more information about BFD, see
High Availability
Configuration Guide
.
To configure BFD for IS-IS: