DHCP server failover behind relay

Alex Bligh alex at alex.org.uk
Wed Sep 5 22:06:30 UTC 2012

--On 6 September 2012 00:08:48 +0300 Vadym Abramchuk <abramm at gmail.com> 

> To simplify the things, here's a short cutoff: is a primary
> DHCP server (running at present), is secondary one
> (actually, it runs in virtual machine). Clients are at different subnet,
> There's a L3 switch routing between subnets (Dell 6024F in
> this case), at one side and at another side. The
> switch acts as a DHCP relay.

How about run carp or similar on the 2 dhcp servers and use iptables
on each server with the -j TEE target (from memory) which will duplicate
the packet and send it to the other server. Clearly you'll want dhcp
listening on a loopback interface or something with the same IP number
on each server, and some proxy arp or similar to get the packet there.

Alex Bligh

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