DHCP failover and fixed-address

[Glenn Satchell]

>Date: Mon, 03 Mar 2008 10:58:04 +0100
>From: Sebastian Hagedorn <Hagedorn at uni-koeln.de>
>To: dhcp-users at isc.org
>Subject: DHCP failover and fixed-address
>
>Hi,
>
>we're currently using ISC dhcpd 3.0.3 in a failover setup. From previous 
>discussions I think I know (but am uncertain) that 3.0.3 does not support 
>host statements with fixed-address in failover mode. However, it seems to 
>work (somewhat). We have many lines like this:
>
>host ap1200-ustb-ort-1                  {hardware ethernet 
>00:0c:30:60:09:09;fixed-address 172.20.15.2;}
>
>They are in both our server's configs. Both servers are configured as 
>helper-addresses on our Cisco routers. Both servers get and serve the 
>requests. I don't think there's any harm in that, but I wanted to make sure 
>...
>
>Also, ISTR that some newer version of dhcpd properly supports such 
>scenarios, but I haven't been able to find anything in the release notes. 
>Am I confused?
>

That's eaxctly the right way to do it. In fact if you only have fixed
addresses you don't need failover at all. Since both servers return
exactly the same information, then it doesn't matter which one (or both
even) reply to the client request.

FOr newer releases you may be thinking of reserved leases. While these
seem to work, the only way to enable them is by editting the leases
file or a complex omapi interface.

regards,
-glenn