[nsp] Graceful shutdown

[sam_ml at spacething.org]

Hi,

I've been thinking about some expect scripts that would shut a router down
gracefully (ie. without packet loss), by giving backup routers time to
takeover traffic forwarding before the power cycle.

The existing configuraion would be saved, and then an expect script would
modify it to effectively make _it_ the backup router, then reboot it some
time later - say 120 seconds - without saving the modifications.

For HRSP/VRSP you could lower the priority of each of the groups to below
that of a pre-empting backup router. For BGP sessions configuring
"prefix-list none in"/"prefix list none out"  for every peer should give
BGP time to converge before the router reboots.

It might also be possible to do this with some Layer2 ethernet devices by
raising the spanning-tree cost of every port in an attempt to deflect
traffic away from it.

Does this seem reasonable? Does something like this already exist, or 
should I get out my expect hat?

Sam