From: Albert Lu (albert_ccie@xxxxxxxxx)
Date: Tue Nov 27 2001 - 17:38:12 GMT-3
I agree with what you are saying, and if route-maps and distribute-list are
applied to prevent route feedback, you would need to know exactly what
networks are in the routing domain so that you can create the proper
access-list. Tagging could work, but then some routing protocols don't
support tagging.
>From my experience, it's best to use distribute-list for DV protocols and
route-maps for LS protocols. What about the distribute-list 10 out ospf 10
command, where you are applying the distribute-list to the routing protocol
being redistributed in, would that be the same as using a route-map?
Albert
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Hansang Bae
Sent: Tuesday, November 27, 2001 6:08 PM
To: ccielab@groupstudy.com
Subject: RE: flsm to vlsm
At 02:26 PM 11/27/2001 +1100, Albert Lu wrote:
>[snip]
>I'm pondering this question as well, as I see from examples in Doyle that
>redistribution between IGPs should be done carefully, so filtering via
>route-maps or distribute-list is required. That means you have to use
>route-maps and distribute-lists for all routers that are doing
>redistribution between two protocols. But Heck!!! I've seen examples that
>don't use filtering, and it still works!!
>My thoughts are that the filtering is there for precautionary measures,
just
>in case routes do feed back into the routing protocol it originated from.
>There's also the admin distance that has to be taken into account of.
>If anyone has any suggestions of the proper way of doing this, please let
me
>know
Folks,
While I understand that people are fretting about the smallest detail of
the lab (e.g. what's consider superfluous command...) there are some
definite engineering standards that should be used in the real world. One
of these is "if you redistribute, you need to route-map/distribute-list
what your redistributing." If you don't... sooner or later, you'll
experience rolling blackouts. Just about every book on IGP has examples
of route feedback causing temporary/rolling blackouts. This won't happen
every single time as it's a function of topology and routing protocols in
use. But sooner or later, you will be bitten by this.
So you should ALWAYS use route-maps (I prefer them to distribute-lists) to
control redistribution.
hsb
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