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Understanding the SPF Algorithm Options for OSPF

OSPF uses the shortest-path-first (SPF) algorithm, also referred to as the Dijkstra algorithm, to determine the route to reach each destination. The SPF algorithm describes how OSPF determines the route to reach each destination, and the SPF options control the timers that dictate when the SPF algorithm runs. Depending on your network environment and requirements, you might want to modify the SPF options. For example, consider a large-scale environment with a large number of devices flooding link-state advertisements (LSAs) through out the area. In this environment, it is possible to receive a large number of LSAs to process, which can consume memory resources. By configuring the SPF options, you continue to adapt to the changing network topology, but you can minimize the amount of memory resources being used by the devices to run the SPF algorithm.

You can configure the following SPF options:

  • The delay in the time between the detection of a topology change and when the SPF algorithm actually runs.
  • The maximum number of times that the SPF algorithm can run in succession before the hold-down timer begins.
  • The time to hold down, or wait, before running another SPF calculation after the SPF algorithm has run in succession the configured number of times.
 

Related Documentation

 

Published: 2012-12-08

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