The graceful-restart interval command sets the GR T3 timer.
The undo graceful-restart interval command restores the default T3 timer.
By default, the GR T3 timer is 300 seconds.
| Parameter | Description | Value |
|---|---|---|
interval-value |
Specifies the GR T3 timer. |
The value is an integer that ranges from 30 to 1800, in seconds. Setting a value greater than that of the GR T2 timer specified using the graceful-restart t2-interval command is recommended. If the value is smaller than that of the GR T2 timer, the GR may fail. |
Usage Scenario
IS-IS GR can be classified into restarting GR and starting GR based on the restart type. The restarting GR is triggered by a master/slave main control board switchover or an IS-IS process restart, while the starting GR is triggered by a restart of the IS-IS-enabled router.
During a restarting GR, the restarter restarts the protocol and starts the T1, T2, and T3 timers at the same time. The value of the T1 timer indicates the longest time during which the GR restarter waits for the LSP from the GR helper. The value of the T2 timer indicates the longest time during which the system waits for the LSDB synchronization. The value of the T3 timer indicates the longest time that a GR lasts. A router disables the T3 timer after the LSDB synchronization ends in all areas. If LSDBs are not synchronized yet when the T3 timer expires, the GR fails.
You can run the graceful-restart interval command to adjust the value of the T3 timer so that the LSDB synchronization can end before the T3 timer expires, which prevents the GR failure.
Prerequisites
The GR of the IS-IS process has been enabled using the graceful-restart command.
Configuration Impact
If the graceful-restart interval command is run on an IS-IS-enabled router, interval-value is used as the holdtime of its neighbor during the GR.
Precautions
The graceful-restart interval command is applicable only to restarting GRs.