From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Sun May 16 2004 - 21:49:12 GMT-3
At 7:59 AM +1000 5/17/04, Fernando, Emil wrote:
>Hi Group,)
>
>In OSPF there are two interface commands ( ip ospf database-filter and ip
>ospf flood-reduction ) that we can use to improve bandwidth usage.
>Can someone help me to understand when I should use these commands and which
>command is more effective than the other one. What OSPF does when these
>commands ara enabled ? Can I use these commands on a tail site to improve
>the routing performance of the tail site ?
>
Before trying to use these features, first, how have you determined
there is a bandwidth problem that needs to be fixed, or how would you
approach it? Second, if there is a bandwidth problem, there may be
better ways to fix it than tuning OSPF at the protocol level.
Still within OSPF, one reason you may have a bandwidth problem is
that your areas are too large, or have too many inter-area/external
routes injected into them. Due to such sizing, there may be too many
LSAs to transfer, and they may not, in any case, be useful to tail
routers.
Flooding reduction is intented for large, stable networks, as often
found in ISPs or some well-run enterprise networks. You can think of
it as a means of applying the logic in the demand circuit extension
to general OSPF, which stops reflooding LSAs simply because they have
aged out, and only refloods when a significant topological event
occurs. The desire to minimize updates in large, stable networks is
one reason many ISPs use ISIS as their IGPs, because ISIS has always
had good facilities for minimizing updates in what can be single
areas of over 1000 routers. See
http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guide09186a008008011e.html
-- =============================================================================== "What Problem are you trying to solve?" ***send Cisco questions to the list, so all can benefit -- not directly to me*** ******************************************************************************** Howard C. Berkowitz presentation downloads by anonymous ftp from www.netcases.net.
This archive was generated by hypermail 2.1.4 : Wed Jun 02 2004 - 11:12:12 GMT-3