RE: BGP Config

I have done the pre-pending already as a precaution but it doesn't have
any effect on AT&Ts side because they are aggregating the prefix. I was
thinking possibly something similar to BGP conditional advertisement?

Timothy Chin

CCIE #23866

________________________________

From: Shaughn Smith [mailto:maniac.smg_at_gmail.com]
Sent: Wednesday, January 05, 2011 2:54 AM
To: Timothy Chin
Cc: ccielab_at_groupstudy.com
Subject: Re: BGP Config

You could try AS Path pre-pending on the low bandwidth link, or you
could ask AT&T to not aggregate and advertise the correct prefix and ask
the other ISP to advertise the aggregate.

CCIE # 23962 (SP)

On Wed, Jan 5, 2011 at 9:48 AM, Timothy Chin <tim_at_1csol.com> wrote:

I've been working on a BGP configuration between one site multihomed to
2 ISPs. One ISP is basically a backup with a low bandwidth connection
and the other ISP is AT&T. AT&T assigned the Class C and I am
advertising the network. The problem is that AT&T is aggregating the
block and since I am advertising the specific class C all incoming
traffic is coming through the low bandwidth connection because of the
longest match. I hate to say my BGP is a little rusty but how would I be
able to conditionally advertise the longest match to the low bandwidth
ISP so that all traffic comes through AT&T via the aggregate?

Timothy Chin

CCIE #23866

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Received on Wed Jan 05 2011 - 03:12:39 ART