Setting an Interval for Updating LSAs

Context

OSPF stipulates that LSAs are updated at an interval of 5s to prevent network connections or frequent route flapping from consuming excessive network bandwidth or device resources.

On a stable network where routes need to converge fast, you can set the LSA update interval to 0s so that the topology or route changes can be immediately advertised over the network through LSAs, thereby speeding up route convergence.

Procedure

Run system-view

The system view is displayed.
Run ospf [ process-id ]

The OSPF process view is displayed.
Run lsa-originate-interval { 0 | { intelligent-timer max-interval start-interval hold-interval | other-type interval } ^* }

An interval for updating LSAs is set.
- The parameter intelligent-timer indicates that an intelligent timer is used to set the interval for updating Router-LSAs and Network-LSAs.
- The parameter max-interval specifies the maximum interval for updating LSAs, in milliseconds.
- The parameter start-interval specifies the initial interval for updating LSAs, in milliseconds.
- The parameter hold-interval specifies the hold interval for updating LSAs, in milliseconds.
- The parameter other-type interval indicates an interval for updating LSAs other than Router-LSAs and Network-LSAs.
By default, an intelligent timer is enabled. After an intelligent timer is enabled, the default maximum interval for updating LSAs is 5000 ms, the default initial interval is 500 ms, and the default hold interval is 1000 ms. The mechanism of the intelligent timer is as follows:
1. The initial interval for updating LSAs is specified by start-interval.
2. The interval for the nth (n ≥ 2) LSA update is equal to hold-interval x 2^(n-2).
3. When the interval specified by hold-interval x 2^(n-2) reaches the maximum interval specified by max-interval, the maximum interval is used for the subsequent three LSA updates. Then, OSPF goes back to step 3.a and updates LSAs at the initial interval specified by start-interval.