Setting the SPF Calculation Interval
To improve the fault location efficiency on an IS-IS network and prevent SPF calculation from consuming excessive system resources, set the SPF calculation interval to a proper value.
Context
A network change always triggers IS-IS to perform SPF calculation. Frequent SPF calculation will consume excessive CPU resources, affecting services.
To solve this problem, configure an intelligent timer to control the interval for SPF calculation. For example, to speed up IS-IS route convergence, set the interval for SPF calculation to a small value, and set the interval to a large value after the IS-IS network becomes stable.
Procedure
- Access the system view.
- Access the IS-IS process view.
isis [ process-id ]
- Set an SPF intelligent timer.
timer spf max-interval [ init-interval [ incr-interval ] ]
During the first SPF calculation, the required delay time is init-interval. During the second SPF calculation, the required delay time is incr-interval. Subsequently, for each change, the required delay time is twice that of the former change until the max-interval. The required delay time keeps stable at the max-interval for three changes or the IS-IS process is restarted, the interval returns to the init-interval.
If the incr-interval is not adopted, the init-interval is adopted as the delay time for the first SPF calculation. Then, the max-interval is adopted as the delay time. The required delay time keeps stable at the max-interval for three changes or the IS-IS process is restarted, the interval returns to the init-interval.
If only the max-interval is adopted, the intelligent timer turns into a common one-time triggering timer.
- (Optional) Set the maximum duration for SPF calculation.
spf-slice-size duration-time