From: Jonathan Hays (nomad@gfoyle.org)
Date: Sat Jan 31 2004 - 10:10:13 GMT-3
you wrote:
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
>Behalf Of alsontra@hotmail.com
>Sent: Saturday, January 31, 2004 3:40 AM
>To: ccielab@groupstudy.com
>Subject: Redistribution using distance - alone
>
>
>Hi Group,
> I am sure that many of you have read the posts
>on GS concern
>redistribution using -just- admin distances. My personal
>conclusions are that
>this type of redistribution can cause temporary routing loops
>and route feed
>back. In one case, I have seen distance based redistribution
>cause a loop
>lasting 240 seconds.(RIP Flush time) I've observed that it is
>possible to make
>this type redistribution work, but it's far from bullet proof. My new
>philosophy is to block feed back using whatever method is a
>available, e.g.
>route-maps, distribution list, etc. If anyone is interested
>in the scenarios
>that brought me to this conclusions, please email me and I'll
>explain in
>detail.
>
>In any event, I'm interested to know if anyone has come to
>similar conclusions
>or even what the current best practices are regarding redistribution.
>
>Thanks,
>Alsontra
= = =
I have no argument with your conclusion. However, consider this:
One tradeoff to keep in mind between the "Administrative Distance (AD)
method" versus the "ACL Blocking method" is that the former allows
dynamic recovery from the condition of losing a specific, more desirable
route. In other words, for a given duplicate route, the AD method allows
the router to put the less desirable route into the table if the more
desirable route stops being advertised for some reason (e.g., link
failure). The ACL Blocking method just blocks the less desirable route
statically and if the more desirable route goes away you have *no* route
to the destination.
Depending on your requirement, it might be worth a short, temporary
routing loop to use the AD method.
Something to consider . . .
-Jonathan
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