Routers already do this, it's generally called fast external fallover. If an interface on the router goes down it immediately takes down whatever BGP peer was coming across that link.
Sorry for the deleted comment - after circulating this article internally, I learned Arista already has better solutions for this particular problem than writing handlers to interface statuses. Decided to retract my comment (while you were replying, incidentally) as there are a number of solutions you can implement on a switch involving BGP knobs, fast-server failover, ECMP and consistent hashing.
mprovost|11 years ago
mrmaddog|11 years ago