[c-nsp] Moving a BGP session to different interface

[Nick Hilliard]

On 25/09/2014 18:19, Randy wrote:
> I'm tasked with moving a BGP session on a 6500 from a 1GE to a 10GE
> interface (live environment).   BGP session details are staying the same. 
> The BGP peer IPs (both v4 and v6) are assigned directly to the existing 1GE
> interface (no SVI, ect).
> 
> Is it as simple/possible as configure the new interface with the same IP's
> but in a shutdown state, move the x-connect, shut the old interface and
> unshut the new interface?   Or will IOS block me from doing this (two
> interfaces with the same IP) -- in other words, the IPs will need to be
> removed from the old interface first?

yes, they will need to removed.

> Thanks for any advise or tips on keeping downtime / CLI work to a minimum :)

if BGP uses the address defined on an interface that you need to migrate,
you will have downtime on that bgp session.  Standard best practice is to
block all inbound and outbound prefixes on the session, then gracefully
shut down the session, then migrate the interfaces, then bring bgp back up
again.  If this is an ebgp session, you will briefly lose connectivity due
to your upstreams' non-zero MRAIs, so you will need to do this in a
scheduled maintenance window.

Nick