From: Steve McNutt (lpd@xxxxxxxxxxxxxxxx)
Date: Mon Oct 30 2000 - 22:37:53 GMT-3
I am struggling with route redistribution, finding it a difficult topic to
master. although I'm sure there are many folks on the list who have a much
better grasp of the subject than I, I'll share with you some of what I have
learned thus far. Since the trail is still 'fresh' in my mind I might be
able to point out things other people have already internalized.
1. Read the route redistribution chapters from the Doyle and Caslow books.
read them again. if you're at all spotty on any of the major routing
protocols, brush up, you will need good recall of how each one works.
Here's the bad news. Neither of these two excellent books cover the topic
in depth. They really just give you enough to get started.
2. loops caused by redistributing connected networks are easy to create and
difficult to diagnose. everything might be fine until you add a third
routing protocol or DDR into the mix and then all hell breaks loose. for
example If you are redistributing RIP or IGRP into OSPF without filtering,
you are probably redistributing your connected networks into OSPF. This
could become a problem in certain situations.
3. If you are redistributing between OSPF and IGRP it's easy to get burned
because IGRP has a lower administraive cost than OSPF.
4. Distribute lists will only get you so far. sometimes distribute-lists
aren't precise or flexible enough. That's when route maps and detailed
knowledge of routing protocol interaction come into play.
5. route redistrbution is chocked full of landmines. route maps and
distribute lists allow you to assert the control you need to solve almost
any redistribution problem. For the more complex issues these tools will do
you no good if you don't understand *exactly* what needs to be done in a
given situation. This is where I have problems.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
tom cheung
Sent: Monday, October 30, 2000 4:53 PM
To: ccielab@groupstudy.com
Subject: route redistribution
Will someone please clear my confusion as to when to use ditribution list
when redistribute from one routing protocol to another? For example, RA is
running ospf and rip and is doing mutual redistributioin. When I inject rip
routes into ospf domain, these routes will show up as ospf E1 or E2 routes.
Correct me if I am wrong, when RA redistribute ospf back to rip, the
original igrp routes will be installed in RA's routing table as ospf routes
rather than rip routes because of ospf's better admin distance. Does it
mean that distribution list should always be used when doing mutual
redistribution to prevent route feedback?
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