[c-nsp] BGP path preference

[Gunjan GANDHI (BR/EPA)]

Do you receive any MED values from your upstream providers?
Also as-prepend on the Cox circuit would do the trick as well.

Cheers 

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Justin Shore
Sent: Wednesday, 29 August 2007 2:24 PM
To: 'Cisco-nsp'
Subject: [c-nsp] BGP path preference

I have a situation with one of our upstreams that I'm trying to fix.  We
peer with Level3 (3356), specifically we peer with 19094 which is the
old Telcove (Adelphia) infrastructure that L3 bought and is slowing
migrating to 3356.  I'm having trouble pushing traffic to that circuit. 
  The preferred route is generally the shorter Cox (22773) path.  I'm
matching about 100 L3 prefixes to raise the weight and local pref, just
like I am for our Cox circuit and our AT&T circuit but I'm still seeing
plenty of Cox paths chosen over the L3 path.  This is primarily because
a typical prefix advertised over L3 arrives at my border with "19094
3356 " and other ASNs whereas Cox may still have the same number of
backend ASNs but only 22773 once it enters the Cox AS.

Does anyone have any suggestions on how to work around this?  L3 will
eventually fix it when they eliminate 19094 but who knows when that will
be.  I thought about trying to use a regex to match "19094 3356" to
raise local pref even higher.  I also see plenty of routes that from
3356 directly to 22773 (L3 peering w/ Cox wo/ Telcove in the middle).  I
could try to match routes that originate on 3356 and 19094 and raise the
local pref of those prefixes.  Do I need to raise it on one AND lower it
on the other border router or would doing it on one suffice and be
manageable?  Would this regex matching be a good best (better?) practice
for all circuits over matching an ACL or prefix-list of prefixes?  If so
would one match on origin or simply if the ASN was in the path?

I have L3 and AT&T on one border and Cox on another.  There's an iBGP
mesh between both borders and both cores.

Thanks for any suggestions,
  Justin

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