Controlling SPF calculation interval
Based on the LSDB, an ISIS 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 minimuminterval is adopted. If network changes become frequent, the SPF calculation interval is incremented by incrementalinterval × 2^{n}^{2} (n is the number of calculation times) each time a calculation occurs until the maximuminterval is reached.
To control SPF calculation interval:
Step  Command  Remarks 

1. Enter system view.  systemview  N/A 
2. Enter ISIS view.  isis [ processid ] [ vpninstance vpninstancename ]  N/A 
3. Configure the SPF calculation interval.  timer spf maximuminterval [ minimuminterval [ incrementalinterval ] ]  By default:
