nanog mailing list archives

Re: Policy-based routing is evil? Discuss.


From: Fred Reimer <freimer () freimer org>
Date: Fri, 11 Oct 2013 18:41:20 +0000

I think they are referring to something like Cisco PBR, where you
configure routing policy statically on each hop.  Yes, it can be
configured to fail over, etc, but inherently it is a management nightmare
if you are configuring PBR on each device in your network.  May as well
move back to static routing on everythingÅ 

Used sparingly, I'd agree that it does have its uses.  One use I can think
of is to use PBR to direct traffic for testing a new circuit or path while
not cutting everything over.  That is, until it is sufficiently tested,
and then everything would be cut over and the PBR removedÅ 


On 10/11/13 2:33 PM, "Jay Ashworth" <jra () baylink com> wrote:

----- Original Message -----
From: "joel jaeggli" <joelja () bogus com>
you take all the useful information that an IGP could be (or is)
providing you, and then you ignore it and do something else.

Well, I tell you what.

My perception of where this was a good idea is the use case a recent
client might have for it:

Two consumer-grade uplinks (FiOS 150 and RR 100, specifically); primary
application is callcenter, VoIP to a service provider Elsewhere.

I would set it up so that all the VoIP and callcenter web traffic went
over
FiOS *until it failed*, and everything else went Road Runner *unless it
failed*. 

This keeps the general traffic out of the hair of the latency/PPS
sensitive
traffic whenever possible.

Is that not policy-based routing?

Why is it bad?

Cheers,
-- jra
-- 
Jay R. Ashworth                  Baylink
jra () baylink com
Designer                     The Things I Think                       RFC
2100
Ashworth & Associates     http://baylink.pitas.com         2000 Land
Rover DII
St Petersburg FL USA               #natog                      +1 727 647
1274




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