[olug] DHCP config

Obi-Wan obiwan at jedi.com
Mon Feb 25 04:35:17 UTC 2008

> Ok, I am missing something here and I just can't seem to figure out what.  I need to add a second subnet to my DHCP server and I cannot get it configured right.  Here is the dhcpd.conf config:

Let me guess--all your addresses are getting handed out in the 205 subnet,

When a new machine requests a DHCP address, it merely sends out a broadcast
on the ethernet.  There is no IP associated with that broadcast, obviously
(hence the DHCP request).  When your DHCP server sees that request on eth1,
it doesn't know which subnet the client would prefer, so it assumes that
the request belongs on the primary subnet for that interface, which is 205.x.

Now, DHCP has a method to get around this.  We don't use it at work (where
I manage a massive DHCP config), but I've read about it.  You can specify
a "DHCP class" (maybe I have the terminology wrong--my books are at work)
on both the client and in your subnet definition that allows the client
to request that the server classify it a certain way.  You can use that
to hand out leases for a certain class of devices from your 10.x pool.

Hopefully this helps, and I haven't misinterpretted somthing.

Ben "Obi-Wan" Hollingsworth                             obiwan at jedi.com
   The stuff of earth competes for the allegiance I owe only to the
     Giver of all good things, so if I stand, let me stand on the
       promise that You will pull me through.  -- Rich Mullins

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