<div dir="ltr">Hi,<div><br></div><div>I've done further testing and it's seems that the problem is that the DHCPREQUEST unicast messages are being duplicated by the relay agent which is running on the router that connects the client subnet to the server subnet.<br><br>I also found and old thread (link <a href="https://lists.isc.org/pipermail/dhcp-users/2012-April/015310.html">here</a>) which reports there very same problem. The person who started that thread already filled a bug report (<span style="color:rgb(0,0,0);white-space:pre-wrap">ISC-Bugs #29053) but I was not able to find in the release notes if this problem was fixed.</span></div><div><span style="color:rgb(0,0,0);white-space:pre-wrap">
I'm running DHCP v 2.4.8.
Any help would be appreciated.
Thanks.
Gero.</span></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 29, 2015 at 7:12 PM, Gero Palacio <span dir="ltr"><<a href="mailto:gero.palacio@gmail.com" target="_blank">gero.palacio@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi All,<div><br></div><div>I found a weird behavior on the DHCP relay agent which is duplicating the outgoing messages from the client when it's not supposed to.</div><div><br></div><div>This is the set up:</div><div><br></div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div>[client] <-> (192.168.1.1) [relay_agent] (10.0.0.1) <-> [pair of failover servers](10.0.1.10 & 10.0.1.11)</div></blockquote><div><br><br><u>What I found is this:</u></div><div><br></div><div><div><b>No. Source Destination Info</b></div><div><br></div><div>-- We're good here. Relay agent duplicate the discovery messages</div><div>-- to send to both pair of servers </div><div><font color="#ff0000"><b>44</b></font> 10.0.0.1 10.0.1.11 DHCP Discover - Transaction ID 0xd2728f7c</div><div><font color="#ff0000"><b>45</b></font> 10.0.0.1 10.0.1.10 DHCP Discover - Transaction ID 0xd2728f7c</div><div> </div><div>-- Receives only 1 response from 1 of the servers. So far, so good.</div><div><font color="#ff0000"><b>47</b></font> 10.0.1.10 192.168.1.1 DHCP Offer - Transaction ID 0xd2728f7c</div><div><br></div><div>-- This bit is also okay. Client broadcasts the request message</div><div>-- relay agent sends 2 messages (one to each server)</div><div>-- receives only 1 response (good).</div><div><font color="#ff0000"><b>48</b></font> 10.0.0.1 10.0.1.11 DHCP Request - Transaction ID 0xd2728f7c</div><div><b><font color="#ff0000">49</font></b> 10.0.0.1 10.0.1.10 DHCP Request - Transaction ID 0xd2728f7c</div><div><b><font color="#ff0000">50</font></b> 10.0.1.10 192.168.1.1 DHCP ACK - Transaction ID 0xd2728f7c</div><div><br></div><div>-- This is the part where it gets weird. </div><div>-- Client sends 1 requst (WireShark on the client confirms this, not shown) </div><div>-- This message contains:</div><div>-- Relay agent IP address: 0.0.0.0 (0.0.0.0) </div><div><b><font color="#ff0000">52</font></b> 192.168.1.60 10.0.1.10 DHCP Request - Transaction ID 0xd2728f7c</div><div><br></div><div>-- Relay agent (source 10.0.0.1) makes 4 messages!! I dont get this part</div><div>-- These 2 messages contains:</div><div>-- Relay agent IP address: 192.168.1.1 (192.168.1.1) ???</div><div><b><font color="#ff0000">53</font></b> 10.0.0.1 10.0.1.11 DHCP Request - Transaction ID 0xd2728f7c</div><div><b><font color="#ff0000">54</font></b> 10.0.0.1 10.0.1.10 DHCP Request - Transaction ID 0xd2728f7c</div><div>-- These 2:</div><div>-- Relay agent IP address: 10.0.0.1 (10.0.0.1) ???</div><div><b><font color="#ff0000">55</font></b> 10.0.0.1 10.0.1.11 DHCP Request - Transaction ID 0xd2728f7c</div><div><b><font color="#ff0000">56</font></b> 10.0.0.1 10.0.1.10 DHCP Request - Transaction ID 0xd2728f7c</div><div> </div><div>-- The response are received with the client ip and with </div><div>-- the relay agent ip that's facing the client </div><div><b><font color="#ff0000">57</font></b> 10.0.1.11 192.168.1.1 DHCP ACK - Transaction ID 0xd2728f7c</div><div><b><font color="#ff0000">58</font></b> 10.0.1.10 192.168.1.60 DHCP ACK - Transaction ID 0xd2728f7c</div><div><b><font color="#ff0000">59</font></b> 10.0.1.10 192.168.1.1 DHCP ACK - Transaction ID 0xd2728f7c</div></div><div><br></div><div><br></div><div>Why is this happening? Why is the DHCP Relay Agent IP is changing in the DHCP message?<br>I've read the DHCP Handbook chapters discussing relay agents (Ch 7 and 9) and also the chapter that describes the ISC relay agent but it doesn't seem to behave in that way.<br><br>I'm using version 4.2.8<br><br>Thanks for your help.<span class="HOEnZb"><font color="#888888"><br>Gero.</font></span></div><div><br></div></div>
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