Redundant master servers possible?

Guys,

I'm running a minor conserver setup, the funky thing is that it's
spread out across four different sites.  By that I mean I have the
master server running at one site (A) and it connects to all the serial
port concentrators at site A, and at remotes sites B, C & D.

But when I have to take down and reboot the master server, I loose all
console access, which is a bummer.

So aside from setting up multiple master servers, one for each site,
how can I setup things so that I have a master and a standby server,
so that if the master goes down, all the clients know to talk to the
standby box, which picks up the session(s) dropped by the master.

Sure, there could be problems here, but something to at least make DR
easier would be helpful.  I don't care as much about the logs of
what's happened, but keeping the client side from having to make
changes is more key to me.

Thanks,
John
    John Stoffel - Senior Staff Systems Administrator - System LSI Group
  Toshiba America Electronic Components, Inc. - http://www.toshiba.com/taec
	     john.stoffel@taec.toshiba.com - 508-486-1087