DHCP Relay results in wrong DHCP scope



  • I have a virtual pfSense box and a virtual Win2K8 R2 box running under ESXi. I have configured my network switch ports and pfSense to allow one of the pfSense interfaces to operate on VLAN10 while the rest of the network operates on the default VLAN1. I have tested this configuration by connecting a laptop to a switch port dedicated to VLAN10 and allowing the laptop to obtain an IP address from the DHCP server running internally on the VLAN 10 interface of the pfSense box. This all works very well.

    However, now I have disabled the internal pfSense DHCP server on all interfaces and I have configured the pfSense DHCP relay to relay the DHCP request to my real DHCP server on the Win2K8 R2 virtual machine. The relay appears to work but the resultant IP address is coming from the wrong scope. My VLAN10 interface within pfSense is set to a static IP of 172.29.1.1/24 and I have a 172.29.1.0 active scope configured on the Win2K8 R2 virtual machine. However, my test laptop is obtaining a 192.168.1.100 IP address which is the DHCP scope for VLAN1 (not VLAN10). It appears to me that pfSense is relaying the DHCP request with the wrong scope information. Is there any way to verify this or has anyone ever seen this issue before?



  • SOLVED: Turns out the issue was on my Win2K8 R2 machine. I had placed both DHCP scopes under a superscope which is not required when using VLANs. I moved the two scopes out of the superscope and now I am obtaining the correct IP addresses from the DHCP server.


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