agent.circuit-id (Option-82,2) map to fixed-address

Henrik Sterndorff Jessen hsj at
Thu Mar 29 06:29:28 UTC 2007

I am using dhcp to dish out fixed addresses to users. All users are
connected to cisco switch ports that act as a relay and therefore add
option-82 information to the dhcp query.

But I would like to provision the dhcp server so each switch port (and
therefore each user) is assigned a predefined fixed address.


That requires that I can map the agent.circuit-id to a fixed address.
"host" entries does not work since I don't know the mac address of the
end users.


But I have spend hours on end reading man pages and googling for a way
to do this. Please help me.


The only work around I have found is using pools and user groups:


class "user-john" {

       match option agent.circuit-id;



subclass "user-john" 00:04:00:5C:03:04; # This is the cisco switch
option-82 addition.


subnet netmask {

        pool {

                allow members of "user-john";


                log (info, "subnet hit");




This seems to work. But I am not shure this scales to 10.000's of users.


Thanks in advance



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