Subject: multi-net and DHCP

From: mcantaloube <[email-masked]>
Date: Tue, 21 Sep 1999 13:36:07 -0400 (EDT)

Here is my problem,

I have two logical IP networks linked by a bridge (two logical IP
networks on the same physical segment). I would like to use DHCP to
configure hosts plugged on the twice networks:
- 10.30.0.0/16
- 10.31.0.0/16

The question is: how can I do to be sure that hosts that actually have
an IP address in the 10.30.0.0/16 network, keep an address in the same
logical network (and the same for hosts of the 10.31.0.0/16 network).
DHCP server will not be able to detect client's subnet since no relay
agent are installed.

I am using a NT 4 server so I can not use a pool of MAC addresses linked
to a pool of IP addresses.

Thank you for your help

---

From: Ted Lemon <[email-masked]>
Date: Tue, 21 Sep 1999 15:20:04 -0400 (EDT)

What you are proposing is probably too difficult.  If you want to have
two seperate subnets, use a router, not a bridge.   If you can't do
that, then you should either use static IP address allocation, or use
the ISC DHCP server's classing capabilities.   Either way, though, you
will have to enter each machine's identification information into the
DHCP server and tell the DHCP server either what address or what
subnet it belongs to - there's no way to do it automatically with the
network configuration you've described.

			       _MelloN_

---

From: Bernie Volz <[email-masked]>
Date: Tue, 21 Sep 1999 16:40:41 -0400 (EDT)

One option, which may not may not be possible (assuming that one network
is used on one side of the bridge and the other is used on the other
side):

- Set the bridge up not to forward DHCP broadcast requests. [If this is
possible.]
- Set up a system one the network which does NOT have a DHCP server
act as a relay agent. That way, the DHCP requests will come from in
with a GIADDR value and the DHCP Server can know that the hosts are
on that other network and assign them the correct addresses.

But, this is basically setting up a normal routed configuration (so why
not just use a router).

- Bernie Volz

Date: Tue, 21 Sep 1999 15:30:09 -0400 (EDT)
From: Ted Lemon <[email-masked]>
To: Multiple recipients of list <[email-masked]>
Subject: Re: multi-net and DHCP

			       _MelloN_

---

From: "Bill Moore" <[email-masked]>
Date: Tue, 21 Sep 1999 18:41:29 -0400 (EDT)

UserClass ID is a natural way to award different profiles to different
groups of clients independent of their subnet or MAC address.  Some servers
(including ours) support the ability to define pool qualification by
UserClass ID.

Microsoft supports the option on W2000, Linx/Unix do, our client can be
installed on Win 95/98/NT for the same.

Bill Moore
NTS
http://www.nts.com

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of Ted
> Lemon
> Sent: Tuesday, September 21, 1999 12:30 PM
> To: Multiple recipients of list

---

From: Ted Lemon <[email-masked]>
Date: Tue, 21 Sep 1999 20:04:09 -0400 (EDT)

> installed on Win 95/98/NT for the same.

The cost of installing new clients on every Win95 box (in time, not
money) may be fairly high, depending on the experience level of your
userbase, and depending on your userbase to say to what network they
are connected is also fairly expensive, but otherwise this is
certainly a viable solution.  Personally, I'd say that installing a
router would be a better solution, but this solution is probably in
the same order of magnitude of difficulty as maintaining a client
database on the server.

			       _MelloN_