Controlling SPF calculation interval

Based on the LSDB, an IS-IS router uses the SPF algorithm to calculate the shortest path tree with itself being the root, and uses the shortest path tree to determine the next hop to a destination network. By adjusting the SPF calculation interval, you can prevent bandwidth and router resources from being over consumed due to frequent topology changes.

When network changes are not frequent, the minimum-interval is adopted. If network changes become frequent, the SPF calculation interval is incremented by incremental-interval × 2^n-² (n is the number of calculation times) each time a calculation occurs until the maximum-interval is reached.

To control SPF calculation interval:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter IS-IS view.	isis [ process-id ] [ vpn-instance vpn-instance-name ]	N/A
3. Configure the SPF calculation interval.	timer spf maximum-interval [ minimum-interval [ incremental-interval ] ]	By default: The maximum interval is 5 seconds. The minimum interval is 50 milliseconds. The incremental interval is 200 milliseconds.

Step

Command

Remarks

1. Enter system view.

system-view

N/A

2. Enter IS-IS view.

isis [ process-id ] [ vpn-instance vpn-instance-name ]

N/A

3. Configure the SPF calculation interval.

timer spf maximum-interval [ minimum-interval [ incremental-interval ] ]

By default:

The maximum interval is 5 seconds.
The minimum interval is 50 milliseconds.
The incremental interval is 200 milliseconds.

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