[c-nsp] Graceful way to terminate BGP Session

[Pete Templin]

Voll, Scott wrote:

> We are going to terminate one of the former ISP BGP sessions.  Is there
> a way to do this gracefully without causing all sorts of routing issues?
> I'm thinking shutting down the Gig port is not my best option.  Do I
> just remove the BGP Neighbor?  Will that cause me issues also?

We normally keep "maintenance" route maps for each provider on the 
relevant routers, and apply them before maintenance events.  Inbound we 
apply a lower local preference, outbound we signal/request lower local 
preference and apply several prepends.  For providers where we have 
multiple links, we normally keep an additional set of route maps handy 
that increase MED, which allows us to reconverge our traffic within the 
provider's network but not change our provider/provider balance.

Of course, a simple no-routes route map is always available to use when 
we're definitely not going to use a connection.

pt