DHCP issues

[Planker1]

I Have a Windows DHCP Server installed in a VM on ESXi 4 that can issue address to it's local subnet with out any issues. I setup the DHCP server for my other subnets and enabled the DHCP relay command on my Cisco Router.

the subnets that use the DHCP relay do not get addresses issued to them. the DHCP server logs do not show any actions being taken, When sniffing the traffic I do see the DHCP Discover packet getting to the server, as the logs confirms the DHCP offer packet is not seen in the packet capture.

I don't see what could be wrong with the DHCP server, if it is authorized and has scopes setup it will issue addresses

the DHCP relay is working or else the DHCP discover packet would not be reaching the server.

so I am looking to either how the ESX server's switch(Cisco 3550) port is configured or something in the ESX virtual switch(not may options to configure so most likely not)

Switch port current config

!

interface FastEthernet0/35

description Router

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 5,10,15,20,200

switchport mode trunk

switchport nonegotiate

end

everything except DHCP request spanning VLANS seems to work fine currently using static addresses/other DHCP server solutions and everything else is working fine would like to get this fixed to simplify DHCP management

[karavinds1]

Did you happen to check the firewall settings between these network. Looking at the last part of your question I understand all communication works fine except for DHCP. Correct me if I am wrong!

Aravind K

[Planker1]

Firewall is disabled for testing even though it has rules to enable DHCP, yes everything else works fine. DHCP started on my 2008 R2 Core DC when I wanted to sniff the traffic on the server I move DHCP to my File server, this also ruled out a direct issue with the DHCP install on the first server or Firewall that was enabled on the DC.

[Rumple · Accepted solution]

without a native vlan configured you are not actually tagging the packets...it will use vlan 1

Set a native vlan on that trunk thats not gonig to be a vlan that crosses that trunk link...

That will force all traffic to be tagged and then your ip helpers will work correctly...

[Planker1]

thanks for the help

good thing I pasted the wrong port config I didn't even look at the config of the trunk port to the router I just tested and I am now getting addresses issued !