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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">You'll want more experienced answers, I'm sure, but we are running a fair-sized network for our DHCP - I believe around 45000 devices and roughly 70 subnets. All of those devices
find the DHCP servers via relay agents and we are using failover.<br>
<br>
We do generally see two DHCP offers - one from each server - when a device requests an address. I expected that behavior and saw no reason to be concerned with it. I still don't - I am under the impression that this is how the system is designed to work.<br>
<br>
It has worked fine for us in this fashion for years. We deployed this particular solution in 2007, but I believe it was used for other devices prior to that, so we have used this through several iterations of ISC-DHCP.<br>
<br>
Patrick<br>
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<div style="direction: ltr;" id="divRpF501387"><font face="Tahoma" color="#000000" size="2"><b>From:</b> dhcp-users-bounces@lists.isc.org [dhcp-users-bounces@lists.isc.org] on behalf of Gero Palacio [gero.palacio@gmail.com]<br>
<b>Sent:</b> Monday, June 15, 2015 5:17 PM<br>
<b>To:</b> Users of ISC DHCP<br>
<b>Subject:</b> Re: DHCP Relay agent not forwarding messages to the client<br>
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<div dir="ltr">Hi Simon,
<div><br>
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<div>Thanks for the reply, I did not know if it was a bug or the correct behavior.<br>
<br>
If I may, let me ask you a follow up question. Does DHCP relay works well with a pair of DHCP servers in failover mode?<br>
<br>
I've configured the relay agent described in my previous email to forward the messages to the pair of DHCP servers. Now everytime the relay agent forwards a discovery message from the host, I receive 2 dhcp offers, one from each server. As I've configured split
to 128, only 1 server should reply with an offer.<br>
<br>
If I test the same configuration with hosts in the same subnet as the DHCP servers, the behavior is as expected. The DHCP servers
<u>responds or ignores</u> the discovery messages according to the result of the hash based on the MAC address of the hosts.<br>
<br>
Any idea what might be the problem? Is it even a good idea to run a relay agent and a pair of DHCP servers in failover?<br>
<br>
Thanks!<br>
Gerónimo.</div>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Jun 15, 2015 at 6:18 PM, Simon Hobson <span dir="ltr">
<<a href="mailto:dhcp1@thehobsons.co.uk" target="_blank">dhcp1@thehobsons.co.uk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex; border-left:1px #ccc solid; padding-left:1ex">
<span class="">Gero Palacio <<a href="mailto:gero.palacio@gmail.com" target="_blank">gero.palacio@gmail.com</a>> wrote:<br>
<br>
> CLIENT <---> [eth0] (relay agent) ROUTER-1 [eth1] <---> ROUTER-2 <---> DHCP Server<br>
><br>
> The relay agent runs ONLY on the interface that faces the client, which is eth0: "dhcrelay -4 -i eth0 10.0.1.10"<br>
</span>...<br>
<span class="">> Can anybody tell me if I'm doing something wrong? Is this a known bug?<br>
<br>
</span>It's a known feature. You must also listen on eth1 in order to get the replies from the server - it's just the way the relay agent works.<br>
<br>
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