Dual Homed IP's

[Olaf Hoyer]

On Wed, 12 May 2004, Adam Seniuk wrote:

> I have 2 mail servers, I would like to give those servers 2 ips so if one card
> dies the other will pick it up.
>
> But I am having a problem since most of the configurations that i have read
> up on have 2 different ip blocks. I have one large block that i can pick
> from.
>
> Example:
> em0 192.168.1.200
> em1 192.168.1.201
>
Hi!

For automated failover, there are kinda tricky solutions available.

for manual failover, simply bind the other address as an alias on the
same physical interface on one card, or use a /32 subnet mask on the
second NIC.

BTW: in case of mailers, you could also solve the problem with different
mx records:

>host yahoo.de
yahoo.de has address 217.12.3.11
yahoo.de mail is handled (pri=5) by mx4.mail.yahoo.com
yahoo.de mail is handled (pri=1) by mx1.mail.yahoo.com
yahoo.de mail is handled (pri=1) by mx2.mail.yahoo.com

So you could simply specify some fallback mailer that picks it up, no
fiddling with different IP...

HTH
Olaf

-- 
Olaf Hoyer        ohoyer at gaff.hhhr.ision.net
Fuerchterliche Erlebniss geben zu raten,
ob der, welcher sie erlebt, nicht etwas Fuerchterliches ist.
(Nietzsche, Jenseits von Gut und Boese)