[DHCP] RE: Determining request

[Jonathan Lassoff]

Excerpts from Bruce Hudson's message of Thu Jan 07 13:23:57 -0800 2010:
>     The easiest option in your situation is (assuming your switch has the
> capability) probably to have the switch insert a "agent.circuit-id" 
> option into the DHCP requests. You can then use the option to define a
> class based on which-ever switch port your AP connects to and limit the
> address pool to that class. Only clients connecting through the AP will
> get a dynamic address. A separate VLAN and subnet is definitely cleaner
> but it should not be required if you cannot live with a layer 3 split.
> 
>     Configuring the DHCP server is relatively straight forward. Setting
> up the switch is an exercise for the reader.

Judging from the only documentation for the HP Procurve 4000m (the OP's
switch), it seems like it's relatively old and doesn't support many
features beyond Ethernet bridging, STP, and link aggregation.

I believe the OP also mentioned using a WAP54g as the wireless AP, it
may be possible to get linux installed on here, and use dhcrelay to
write something identifying inside the Relay Agent Information field.
I believe by default, it uses the name of the receiving interface in the
circuit id field.

Be warned though, most WAP54G's don't have much flash memory.

--j