DHCP IP assignment issue - dhcp failover scenario

[Niall O'Reilly]

On 18 Dec 2018, at 19:09, Usman Ahmad wrote:

> Regarding dhcp servers routing; dhcp01 gateway is router1 and dhcp02 
> gateway is router2.

I you have reverse path verification enabled on the downstream (towards 
CPE,
away from DHCP servers) interfaces of the routers, traffic will likely 
be
blocked from the DHCP server which is using the router which is not the
active VRRP partner.

Earlier, Usman Ahmad had written:

> But i dont want to keep both DHCP server replying to one DHCP relay.

I believe that this is a mistake. Every DHCP server has to reply to the 
relay
through which it received the corresponding request.  That's just part 
of the
protocol.

It's been a while since I worked with the kind of setup you describe, so 
some
of my experience may be at odds with current behaviour on the wire.  I 
was
forced to learn that either trying to eliminate duplicate OFFERS or 
trying to
force the route of the response traffic to match my ideas simply broke 
things.

I think you need to let yourself be guided by what works.  The cost of a 
few
packets is insignificant, especially in comparison to the value of your 
time.

I hope this helps.

Niall O'Reilly