Improve OSPF Convergence Time
Background Information
- OSPF relies on a number of timers to control its convergence process.
- Sometimes, timers can make things more stable.
- Low dead-interval on an unstable link will result in flapping adjacencies, which will flood LSAs, and in turn, causes continuous SPF runs.
- Low lsa throttle timers and lsa arrival timers with flapping links in the network will cause floods of LSAs, which will in turn, cause continuous SPF runs.
- Low spf throttle timers with an unstable network will continuously run SPF if it continuously receives LSA updates.
- Other times, they can be the limiting factor that is slowing down convergence.
Summary
- Change hello-interval and dead-interval to improve dead neighbor detection.
- ip ospf dead-interval minimal hello-multiplier for sub-second detection.
- timers throttle lsa all controls the timing of sending LSAs after a change is detect.
- timers lsa arrival controls the timing of accepting LSAs that are received.
- timers throttle spf to change the timing of running SPF after a change has been detected in LSDB.
