IP Routing: OSPF Configuration Guide, Cisco IOS Release 12.4T
OSPF Link-State Advertisement Throttling
OSPF Link-State Advertisement Throttling
Last Updated: October 27, 2011
The OSPF Link-State Advertisement (LSA) Throttling feature provides a dynamic mechanism to slow down link-state advertisement (LSA) updates in OSPF during times of network instability. It also allows faster Open Shortest Path First (OSPF) convergence by providing LSA rate limiting in milliseconds.
History for the OSPF LSA Throttling Feature
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Information About OSPF LSA Throttling
Benefits of OSPF LSA Throttling
Prior to the OSPF LSA Throttling feature, LSA generation was rate-limited for 5 seconds. That meant that changes in an LSA could not be propagated in milliseconds, so the OSPF network could not achieve millisecond convergence.
The OSPF LSA Throttling feature is enabled by default and allows faster OSPF convergence (in milliseconds). This feature can be customized. One command controls the generation (sending) of LSAs and another command controls the receiving interval. This feature also provides a dynamic mechanism to slow down the frequency of LSA updates in OSPF during times of network instability.
How OSPF LSA Throttling Works
The timers throttle lsa all command controls the generation (sending) of LSAs. The first LSA is always generated immediately upon an OSPF topology change, and the next LSA generated is controlled by the minimum start interval. The subsequent LSAs generated for the same LSA are rate-limited until the maximum interval is reached. The "same LSA" is defined as an LSA instance that contains the same LSA ID number, LSA type, and advertising router ID.
The timers lsa arrival command controls the minimum interval for accepting the same LSA. If an instance of the same LSA arrives sooner than the interval that is set, the LSA is dropped. It is recommended that the arrival interval be less than or equal to the hold-time interval of the timers throttle lsa all command.
How to Customize OSPF LSA Throttling
Customizing OSPF LSA Throttling
2. configure terminal
3. router ospf process-id
4. timers throttle lsa all start-interval hold-interval max-interval
5. timers lsa arrival milliseconds
7. show ip ospf timers rate-limit
8. show ip ospf
Configuration Examples for OSPF LSA Throttling
Example OSPF LSA Throttling
This example customizes OSPF LSA throttling so that the start interval is 200 milliseconds, the hold interval is 10,000 milliseconds, and the maximum interval is 45,000 milliseconds. The minimum interval between instances of receiving the same LSA is 2000 milliseconds.
router ospf 1 log-adjacency-changes timers throttle lsa all 200 10000 45000 timers lsa arrival 2000 network 10.10.4.0 0.0.0.255 area 24 network 10.10.24.0 0.0.0.255 area 24
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