Failover/load-balancing with dhcp client bug on "seconds elapsed" field

Simon Hobson dhcp1 at
Thu Apr 15 08:19:42 UTC 2010

Daniel Duarte wrote:

>- We need to give a static IP to our clients based on the option 82 
>location info received by the server;
>- to do so we created matching classes, and pools with only one IP 
>available. On each on those pools we accept only one mach class;
>- when the client sends the first Discover, dhcp0 ignores (I believe 
>he thinks it will be handled by its peer), but dhcp1 writes on the 
>log "peer holds all free leases" (I believe dhcp1 isn't controlling 
>this specific lease);
>- The client keeps trying and incrementing the "seconds elapsed" 
>field on the "discovers". When it becomes greater than our 
>configured "load balance max seconds", dhcp0 answers the request 
>with the usual "offer";
>- The problem is when the client sends the "request", because it 
>sends it with "seconds elapsed" = 0! The transaction id is the same, 
>and all the other parameters seem to be correct except this one.
>- Dhcp0 ignores the request even that on the options the client 
>specifically states that he's answering his offer.

How about not using failover on those pools ? Since they can only 
serve one client*, it doesn't matter if the servers aren't working 
'as a team'.

* Unless someone adds a small switch and puts two clients on the same 
circuit - but then it'll just be their devices that don't work.

Simon Hobson

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