Subject: Re: Sending new LSA

From: "Naidu, Venkata" <[email-masked]>
Date: Tue, 4 Jun 2002 16:16:49 -0400

Attila,

-> - When the LSA is replaced in the LSA database, does the
-> router run an SPF calculation (because the LSA database has changed)?

  Yes, as per OSPF standard, schedule SPF computation
  (partial/whole) when database changes.

  There was some good amount of work done in reducing
  the Routing Table Computation Cost in OSPF using WARs.
  (this work is never published in IETF - because
  figuring out WARs is very difficult and complicated
  task with many limitations)
http://www.isoc.org/isoc/conferences/inet/99/proceedings/4g/4g_2.htm

-> - If the router runs an SPF calculation, which happens
-> sooner? The sending  of the LSA to the neighbours or the
-> SPF calculation?

  This is implementation dependent. Option of local
  convergence w.r.t global one (in the vicinity if
  few negligible seconds). If you delay flooding little
  bit, remember the global convergence will affect
  (based on queuing theory - including propagation
  and processing delays in each and every router).
  My choice - flood first.

--
Venkata.