[137856] in North American Network Operators' Group
RE: BGP Failover Question
daemon@ATHENA.MIT.EDU (Brian Johnson)
Mon Feb 21 16:23:25 2011
From: Brian Johnson <bjohnson@drtel.com>
To: NANOG <nanog@nanog.org>
Date: Mon, 21 Feb 2011 21:21:45 +0000
In-Reply-To: <49274CE9-307A-4C36-B311-01B42DD0C735@iamchriswallace.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Chris,
The best way to resolve this issue is to not use a service provider who tak=
es down your connectivity outside of maintenance windows, but I digress.
This is the nature of BGP. You send your providers routes about your networ=
k prefixes and they send you routes to say the DFZ. When you forward packet=
s to them ,because they sent you routes saying they can get the destination=
s your packets have on them, it is now outside of anything you can do about=
it. It is now up to the peer to forward the packets as they said they woul=
d by sending you prefixes.
This is a trust relationship as you trust they will forward your packets be=
cause that is why you are paying them.
- Brian J.
-----Original Message-----
From: Chris Wallace [mailto:lists@iamchriswallace.com]=20
Sent: Monday, February 21, 2011 3:10 PM
To: NANOG
Subject: BGP Failover Question
I am looking for some help with an issue we recently had with one of our BG=
P peers recently. I currently have two DIA providers each terminated into =
their own edge router and I am doing iBGP to exchange routes between the tw=
o edge routers. Last week Provider A made a policy change "somewhere" in t=
heir network in the middle of the day causing traffic to stop routing. Of =
course this connection happens to be the preferred route for the majority o=
f our inbound and outbound traffic. I never saw our physical link go down =
and never saw our peer drop therefore BGP did not stop advertising routes, =
this caused most of our customers traffic to go nowhere. In order to fix t=
he issue I had to manually shutdown the peer till Provider A confirmed the =
change they made had been reverted. This isn't the first time we have seen=
this issue with our various providers, how can I prevent issues like this =
from happening in the future?
---Chris
