DHCP Relay agent not forwarding messages to the client

[Gero Palacio]

Both servers are in normal mode. I checked using the OMSHELL and also the
status of the servers that's logged in the "dhcpd.leases" file.

To make it clear, what's going on is this:

   1. Host sends DHCPDISCOVERY.
   2. Relay agent forwards this request to both DHCP servers (this is the
   way it's suppose to work).
   3. *BOTH servers replies with a DHCPOFFER message to the client.*
   4. Clients picks one, sends DHCPREQUEST.
   5. The selected server replies back to the client with an DHCPACK.

Step 3 is the one that doesn't make sense to me.

I've done a test with 1 host is in the same subnet as the DHCP servers, and
both of them receives the DHCPDISCOVERY message but actually *one of them
responds back to the client with a DHCPOFFER*, and I understand it's the
way it should work.

Maybe it's me that's understanding this section incorrectly, but that's
actually the way it works when host and servers are in the same subnet as
described above:

Section 5.3 of  IETF Internet Draft - DHCP Failover Protocol
<https://tools.ietf.org/pdf/draft-ietf-dhc-failover-12.pdf>

 In order to implement load balancing between a primary and secondary
 server pair, each server must respond to DHCPDISCOVER requests from
 some clients and not from other clients. In order to do this suc-
 cessfully, each server must be able to determine immediately upon
 receipt of a DHCP client request whether it is to service this
 request or to ignore it in order to allow the other server to service
 the request.



I'll check what Peter and Graham suggested about the secs parameter from
the clients.

Thanks all for your help!
-Gerónimo.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20150616/9ae1a6c6/attachment-0001.html>