[c-nsp] ip migration

[Miquel van Smoorenburg]

On Wed, 2005-12-07 at 10:27 -0500, Kern, Tom wrote:
> We are currently moving all our servers to a different location with a different ip scheme.
>  
> Now aside from checking all apps that have ip's hardcoded in them or anticipating some fubars based
> on clients connecting to the old ip, what is typically the method with which this is done to
> minimize downtime and failure?
>  
> how do net admins do this in the "real" world?

If you can find a way to get the new IPs temporarily routed or tunneled
to the old location, or the old IPS temporarily to the new location, you
can just provision both IPs on all servers for a short time. You then
update DNS. Wait for the TTL to expire so changes have propogated
everywhere. Then turn off the old IPs, if it breaks turn it back on and
fix it, rinse, repeat. Make use of maintenance windows at night.

If you cannot do that, just make sure that you lower the DNS TTL for all
records in all zones that point to your old IPs to something like 5
minutes, so that changes propagate quickly.

Mike.