Subject: DHCP over IP/ATM

From: Juana E Nakfour <[email-masked]>
Date: Tue, 7 Dec 1999 10:36:57 -0500 (EST)

Hello everyone,

 currently we are researching the possiblity of running DHCP over an
IP/ATM network (1577). My question is does DHCP work in such a
network? (DHCP assumes an underlying broadcasting network plus uses
the hardware address as a unique identifier for the client) 
Any help on this subject matter will be greatly appreciated it. Plus
if someone could refer me to any documents covering this topic. Thanks
a lot !!

Cheers !!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Juana Nakfour                         
Software Eng.                         
BedRock Grp.                          
Motorola                              
(847) 435 8925

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From: Philip Legge <[email-masked]>
Date: Tue, 7 Dec 1999 18:28:50 -0500 (EST)

>Date: Tue, 7 Dec 1999 09:28:01 -0600 (CST)
>From: Juana E Nakfour <[email-masked]>
>Subject: DHCP over IP/ATM
>

Hi Juana,

DHCP does work well over ATM but there seem to be interesting 
anomalies, so it would be helpful if any documents regarding this are 
brought to the attention of the list.

At Deakin we are using switched ethernet with ATM implemented between 
switches and router, which works fine except when a client (usually a 
laptop) changes subnet and is booted. When the laptop is booted and 
issues a DHCPREQUEST, ATM is able to deliver the message to the local 
DHCP server; the DHCP server does issue DHCPNAK as it recognises the 
client has changed subnet, however ATM is unable to deliver this 
message back to the client. Without DHCPNAK the client continues to 
use it's previous lease until expiry (and thus can't use the network 
with TCP/IP misconfigured).

Since the problem doesn't occur if the previous lease address expires 
or is released, we have a variety of methods to overcome this - use 
of scripts to force DHCPRELEASE on shutdown or startup, or the 
graphical utilities for Microsoft DHCP clients (winipcfg and 
wntipcfg, the latter is found on the NT4Wks Resource Kit CD).

BTW, DHCP doesn't assume the hardware address to always be a unique 
indentifier, however the various Microsoft clients usually do!

Cheers, Philip

--
Philip Legge <[email-masked]> Deakin Uni - Business & Law- IT Support