Using DHCP with a Cisco VPN concentrator

[John Hascall]

> I have been trying to get DHCP set up for (2) Cisco 3030 VPN
> concentrators.  I have confirmed that the configuration on the devices
> is correct but I am still not able to get an address from the DHCP
> server.  I think the issue may be how the DHCP address is being
> requested.  The VPN client are all on Windows XP and running the Cisco
> VPN client.  Below is what I am seeing on the DHCP server when the
> request is being relayed via the VPN concentrator:
> 
> Jun 16 19:03:05 scratchy dhcpd: DHCPDISCOVER from 00:03:a0:89:22:43 via
> 10.6.1.122: unknown network segment
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

> I think the problem is the multiple DHCPDISCOVER requests coming from
> the concentrator / VPN client.  Below is a section from a Microsoft
> support site:   ...

    I strongly doubt this has anything to do with you problem.

    The error message you are getting says that your DHCP server
    knows nothing about 10.6.1.122 -- the address the requests
    are coming from (which is presumably your VPN Conc).

    You need to have an appropriate subnet definition in
    your dhcpd.conf file which includes that address.
    I do not know what your subnet mask is, but perhaps
    one of these:

         subnet 10.6.1.0 netmask 255.255.255.0 {
         }
    or:
         subnet 10.6.0.0 netmask 255.255.0.0 {
         }
    or:
         subnet 10.0.0.0 netmask 255.0.0.0 {
         }

John