DHCP server failover behind relay

Malte Starostik lists at malte.homeip.net
Thu Sep 6 20:41:52 UTC 2012

Hi Vadym,

Am Donnerstag, 6. September 2012, 23:12:11 schrieb Vadym Abramchuk:

> Just tried -j TEE and got the local loop with two servers copying packets to 
each other :(.
> Any idea on how to avoid this? TTL check looks weird. 

I've been following this thread since you started it but only now a different 
idea comes to mind:

If you've got a working multicast setup in your network, you could maybe have 
the switches forward DHCP traffic to some admin scoped multicast address.
Then you only need to join the DHCP servers to this group address.  IIRC there 
is a patched version of quagga that can do it.  Otherwise, a trivial program 
in just about any language could implement this.
In fact I've tried out such a setup just to see if it works out and it seems 
to do.  Don't have the code anymore though, but it was only like a dozen lines 
in C.


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