I've been monitoring the SPF counters on some routers in the network and wanted to understand if the router performs different parts of the SPF algorithm depending on what information is currently in the database and what new information is received via some LSA.
Consider the following two different scenarios: 1) Suppose I have a transit router that's part of an OSPF network and has an interface which is ethernet. While this router is a transit router, there are no other routers on this enet interface so this interface would be a stub network. Suppose this interface went from the "up" to the "down" state. The router would flood an LSA indicating this network is no longer reachable. WHile this is a transit router, the only change was related to the stub network interface and so there doesn't seem to be a need for all other routers to run the complete SPF as each router's current SPF tree would not change. Does only the "second phase" (terminology from 16.1 in RFC 2328), and not the complete SPF process, get performed for this situation? 2) Same toplogy as above-- router is transit with an ethernet network which has no other routers on. One adds a secondary to the ethernet interface. An LSA gets flooded, but the only change would be the addition of a new network (as opposed to a link changing state). Would only the "second phase" of OSPF be performed? One can see how many SPFs have been performed by a router-- I'm trying to determine if the complete process is performed for any type of LSA change or if only parts of the SPF are performed. If the later, is it possible to see how many complete SPFs where performed and how many of the "just second phase" where performed. Thanks Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=49953&t=49953 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
