The timer spf command sets the delay in SPF calculation.
The undo timer spf command restores the default setting.
By default, the maximum delay in SPF calculation is 5 seconds.
| Parameter | Description | Value |
|---|---|---|
max-interval |
Specifies the maximum delay in SPF calculation. |
The value is an integer that ranges from 1 to 120, in seconds. The default value is 5s. |
init-interval |
Specifies the initial delay in SPF calculation. If the init-interval parameter is not specified, the intelligent timer functions as an ordinary one-time triggering timer. |
The value is an integer that ranges from 1 to 60000, in milliseconds. By default, it is 50 milliseconds. |
incr-interval |
Specifies the incremental delay in two SPF calculations. If the incr-interval parameter is not specified, the delay in SPF calculation for the first time is determined by init-interval. From the second time on, the delay in SPF calculation is determined by max-interval. |
The value is an integer that ranges from 1 to 60000, in milliseconds. The default value is 200 milliseconds. |
Usage Scenario
In IS-IS, route calculation is required when an LSDB changes. Frequent route calculations, however, consume lots of system resources and decrease system performance. Delaying SPF calculation can improve route calculation efficiency. However, a long delay in SPF calculation slows down route convergence.
To speed up route convergence without affecting the efficiency of switches, configure an intelligent timer for SPF calculation. This timer automatically adjusts the delay in SPF calculation based on the LSDB change frequency.
When SPF calculation is performed for the first time, the interval is init-interval. Each time a route changes, the interval is added by incr-interval until the interval reaches max-interval. After max-interval expires without flapping or the IS-IS process is restarted, the delay decreases to init-interval.
When only max-interval is used, the intelligent timer becomes a one-short triggered timer.