Setting the Interval for Updating LSAs
Context
In OSPF, the interval for updating LSAs is defined as 5s. This aims to prevent network connections or frequent route flapping from consuming excessive network bandwidth or device resources.
On a stable network where routes need to fast converge, you can cancel the interval for updating LSAs by setting the interval to 0s. In this manner, changes of the topology or the routes can be immediately advertised on the network through LSAs, thereby speeding up route convergence on the network.
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 } * }
The interval for updating LSAs is set.
- The parameter intelligent-timer indicates that an intelligent timer is used to update OSPF Type-1 LSA (Router LSA), Type-2 LSA (Network LSA), Type-5 LSA (AS-external-LSA), and Type-7 LSA (NSSA LSA).
- 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 specifies the interval for updating OSPF Type-3 LSAs (Network-summary-LSAs), Type-4 LSAs (ASBR-summary-LSAs), and Type-10 LSAs (Opaque LSAs).
By default, the intelligent timer is enabled; the maximum interval for updating LSAs is 5000 ms, the initial interval is 500 ms, and the Holdtime interval is 1000 ms.
After an intelligent timer is enabled, the interval for updating LSAs is as follows:- The initial interval for the SPF calculation is specified in start-interval.
- The interval for the SPF calculation for the nth (n≥2) time is equal to hold-interval × 2(n-2).
- When the interval specified in hold-interval × 2(n-2) reaches the maximum interval specified in max-interval, OSPF updates LSAs at the maximum interval for three consecutive times. Then, OSPF updates LSAs at the initial interval specified by start-interval.
- (Optional) Run lsa-originate-interval suppress-flapping suppress-interval [ threshold threshold ]
The maximum LSA suppression period is configured.
If frequent LSA flapping occurs, the larger value between lsa-originate-interval suppress-flapping and lsa-originate-interval is used as the value of the suppression timer.
By default, if a device receives an LSA, it delays route calculation for 10s in route flapping scenarios.
- Run commit
The configuration is committed.