RE: BGP Failover Question

[Brian Johnson <bjohnson () drtel com>]

Chris,

The best way to resolve this issue is to not use a service provider who takes down your connectivity outside of 
maintenance windows, but I digress.

This is the nature of BGP. You send your providers routes about your network prefixes and they send you routes to say 
the DFZ. When you forward packets to them ,because they sent you routes saying they can get the destinations 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 would by sending you prefixes.

This is a trust relationship as you trust they will forward your packets because that is why you are paying them.

- Brian J.

-----Original Message-----
From: Chris Wallace [mailto:lists () iamchriswallace com] 
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 BGP 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 two edge 
routers.  Last week Provider A made a policy change "somewhere" in their 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 of 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 the 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