BGP Failover Question

[Chris Wallace <lists () iamchriswallace com>]

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