<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Times New Roman; font-size: 12pt; color: #000000'>As Patric said the server should know what subnet a request came from. Then it will be able to assign address from proper pool.<br>Show us DHCP daemon log records containing those requests.<br>In my setup when such a request comes in it looks like this:<br><br>DHCPREQUEST for 10.0.0.1 from xx:xx:xx:xx:xx:xx via 10.0.0.254<br><br>10.0.0.254 in this case is a Cisco switch VLAN interface (which is a router for this VLAN) address.<br>Server knows that request came from 10.0.0.254 network, thus it will assign proper address.<br><br>So, show us some of your DHCP server logs where the requests can be seen.<br><br><br>----- Original Message -----<br>From: "Mike Senko" <Mike.Senko@seattle.gov><br>To: dhcp-users@lists.isc.org<br>Sent: Friday, July 25, 2014 6:15:09 PM GMT -05:00 US/Canada Eastern<br>Subject: single dhcp server with multiple subnets<br><br><style><!--
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</o:shapelayout></xml><![endif]--><div class="WordSection1"><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">I’ve gone through the archives, but haven’t found a solution to using a single dhcp server</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">to service multiple subnets.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">The subnets are set up on a router (non-cisco) that uses dhcp-relay to pass dhcp requests </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">through the configured switch interfaces. The switches are layer 2 and also are configured</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">for dhcp relay.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">The dhcp request packets show up at the server.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">The dhcp server then assigns and address and sends it to the router’s address.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">The problem I’ve run into is the server is always sending the first dhcp address in the first configured</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">subnet regardless of the subnet the request comes from.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">In other words, dhcp ip address assigned is always 10.1.6.200 even if the request comes from 10.1.8.0 subnet.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">If the dhcp request comes from the 10.1.6.0 subnet, all is fine.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">I think the problem is in the dhcp server configuration:</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option domain-name "TestLab.NSC";</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">default-lease-time 600;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">max-lease-time 7200;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">authoritative;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">log-facility local7;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">subnet 10.1.6.0 netmask 255.255.255.0 {</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option routers 10.1.6.2;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">range 10.1.6.200 10.1.6.254;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option subnet-mask 255.255.255.0;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">}</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">subnet 10.1.7.0 netmask 255.255.255.0 {</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option routers 10.1.6.2;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">range 10.1.7.200 10.1.7.254;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option subnet-mask 255.255.255.0;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">}</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">subnet 10.1.8.0 netmask 255.255.255.0 {</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option routers 10.1.6.2;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">range 10.1.8.200 10.1.8.254;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option subnet-mask 255.255.255.0;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">}</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">subnet 10.1.9.0 netmask 255.255.255.0 {</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option routers 10.1.6.2;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">range 10.1.9.200 10.1.9.254;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option subnet-mask 255.255.255.0;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">}</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">subnet 10.1.5.0 netmask 255.255.255.0 {</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option routers 10.1.6.2;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">range 10.1.5.200 10.1.5.254;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">option subnet-mask 255.255.255.0;</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">}</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">This is the entire configuration, there must be something missing. I’m not using dns, just trying to get addresses assigned </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">to the right vlan/subnet. The server is attached to 10.1.6.0/24.</span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font face="Calibri" size="2"><span style="font-size:11.0pt">Thanks, ms</span></font></p></div><br>_______________________________________________
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