DHCP server failover behind relay

Glenn Satchell glenn.satchell at uniq.com.au
Thu Sep 6 02:46:34 UTC 2012

On Thu, September 6, 2012 8:06 am, Alex Bligh wrote:
> --On 6 September 2012 00:08:48 +0300 Vadym Abramchuk <abramm at gmail.com>
> wrote:
>> 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

How many remote subnets are there? If not too many then you could run an
ISC dhcrelay process on a system on each network, doesn't have to be the


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