dhcpd heartbeat cluster und server-identifier

Glenn Satchell Glenn.Satchell at uniq.com.au
Thu Oct 29 13:40:01 UTC 2009

>Date: Thu, 29 Oct 2009 11:13:01 +0100
>Subject: dhcpd heartbeat cluster und server-identifier
>From: stefan novak <lms.brubaker at gmail.com>
>To: Users of ISC DHCP <dhcp-users at lists.isc.org>
>X-BeenThere: dhcp-users at lists.isc.org
>I want to build a dhcpd cluster with heartbeat and drbd for fault tolerance.
>I have 2 dhcp server, every with his own ip (,
>and the active node holds the clusterip
>I've tried to set the server-identifier to, that the
>server listens to this ip.
>But as i see the packes to the client are always sent by the primary
>server ip (eg
>Will that be a problem for the clients when they send the DHCPREQUEST
>to and get an answer from
>Is there a solution for this on isc side? I dont want to use nat for
>this. Or can this just be ignored?
>thanks Stefan

That should be fine. The clients look at the contents of the packet for
the server-identifier to see where they should reply. They do not
automatically use the source IP address.

Note that dhcpd also has its own load-sharing failover implementation
which works very well. You may wish to look at that, as the operating
system configuration becomes much simpler than a cluster.

You may also like to read a longer email I wrote on a related topic
some time ago:



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