Subject: A Question about DHCP and "Mobile" Clients

From: "Cosden, Geoffrey J." <[email-masked]>
Date: Tue, 17 Nov 1998 17:23:12 -0500 (EST)

Hello,

I just joined this list today and hope that it is one where subscribers are
allowed to post a message.

Any insight on the following situation would be greatly appreciated:

We have two IP-based networks which users may access by turning a switch.
One of these networks is connected to the Internet and the other is not.  We
had a plan to implement private IP addressing (10.xx.xx.xx; 172.16.xx.xx,
etc.) on the network that is not connected to the Internet.  

Most of the clients are Win95 or WinNT machines and the DHCP servers are on
IBM AIX machines.

The problem arise when a user on our normal network tries to turn the switch
to get onto the private network and get an IP address.  Windows DHCP clients
ask for the last address the client had again (even when you have done a
release in Winipcfg).  The DHCP server looks at the client's request and
decides that the client is on a different network and refuses to provide an
IP address.

Is anyone aware of a way to tell the DHCP server to ignore the fact that the
client is asking for an address from a different network?  Alternately, is
anyone aware that such a solution is an impossibility?

Many thanks in advance for your response,
-Geoff Cosden
[email-masked]

---

From: Ye Gu <[email-masked]>
Date: Wed, 18 Nov 1998 18:49:36 -0500 (EST)

It sounds like a NACKing problem with the DHCP server.  The server
should NACK the client if it has moved to a different subnet.

The only way to tell for sure whether this is a server or client
problem is to look at a network sniff.

Thanks!

Ye

-----Original Message-----
From: Cosden, Geoffrey J. [mailto:[email-masked]]
Sent: Tuesday, November 17, 1998 2:25 PM
To: Multiple recipients of list
Subject: A Question about DHCP and "Mobile" Clients

Hello,