From: Peter Van Oene (vantech@xxxxxxxxxxxx)
Date: Mon Sep 13 1999 - 14:35:01 GMT-3
Can anyone clarify if my understanding of route-maps is correct?
I see them used in two places:
1: Directing routed packets
By using policy routing, packets flowing through the router can
be policy routed via the route map statements. Specifics like
next hop or interface to be forwarded on make these modifications.
In essence, packets matching the match criteria are pulled out of the
normal routing process and are policy routed. Packets not matching
a match criteria are forwarded to the normal routing process.
2: Influencing IGP redistribution
At an point of IGP or IGP to EGP redistrbution, route-maps enable
an administrator to modify route parameters like metrics, metric types,
and specific BGP paramaters. Packets not matching a match criteria
are not redistributed. Hence it is useful to add a default match
criteria
if your intent is only to modify some routes but continue to redist the
rest
The key point is that Route-maps are not used within a single IGP to
modify IGP paramenters - For example, if I config an ip local policy
route-map to modify OSPF metric types, it simply isn't going to do
anything.
Am I correct in my statements or I am missing something?
(sometimes when prepping for the lab I find you distance yourself
from practicality and try to achieve the unnecesary ::)
Peter Van Oene
Senior Systems Engineer
UNIS LUMIN Inc.
www.unislumin.com
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