From: Gregory Gombas (ggombas@gmail.com)
Date: Mon May 07 2007 - 11:57:29 ART
Hello Group,
I was wondering if someone can post some guidelines or suggest
recommended reading regarding route redistribution and preventing
route loops?
I understand there are two main techniques used to preventing route feedback:
1. Use route maps to deny tagged routes from being fed back into the
same routing domain.
2. Change the administrative distance on selected routes to prefer
routes learned from one source over another.
I'm not always sure which method to use for a given scenario.
For instance I was recently working on IE Lab 2 where you have the
same EIGRP AS connecting to an OSPF backbone like so:
EIGRP
| \
OSPF |
| /
EIGRP
Normally when I have more than one point of redistribution I
immediately configure route maps to tag and deny routes from being fed
back. In this scenario, however, tagging the EIGRP routes on one end
causes them to be denied on the other end (as is the case when the
link connecting the EIGRP networks goes down and its forced through
the OSPF backbone). I had to tweak the administrative distance on a
few routers to get this working.
So my questions is, is there a general rule of thumb regarding what
type of scenario requires AD tweaking versus route tagging?
Thanks,
Greg
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