Subject: DHCP No-Go?

From: Ted Lemon <[email-masked]>
Date: Thu, 29 Mar 2001 16:27:05 -0700

A user just made the suggestion I have quoted below on one of the ISC
DHCP mailing lists.  I thought about it for a while, and decided that
it makes sense.  We are in the right phase of protocol development to
do this, and I think it would be easy.  If the group is willing, I'll
write up some language for it.

Basically, what I'd suggest is that we say that if a DHCP server
receives a DHCP Solicit message and knows that it's not going to give
the client an address, it SHOULD send a DHCP Advertise message anyway,
with no addresses for the IA proposed by the client and an error code
saying why it isn't going to give the client an address.  DHCP servers
SHOULD be configurable to not respond to DHCP Solicits from clients
they are configured not to serve.  DHCP clients SHOULD ignore the DHCP
Advertise message if it contains an error code, but MAY use the
DHCP Advertise message to report status to the user if no non-error DHCP 
Advertise messages are received within the suggested timeout.

Also, in DHCPv4 the server has the option of sending a text message
along with the DHCPNAK.   I think that it would be nice to provide
this functionality in DHCPv6 as well, and to *strongly* suggest that
DHCP clients present the information in the message to the user if no
addresses are received.   Right now, I know of no DHCPv4 clients that
do this, although I know of several that can, and should.

I think that this would provide a *much* better level of service for
users of clients in cases where things are going wrong.   I would
again be happy to add text for this.

In case anybody is feeling skeptical about my ability to deliver, BTW,
I am about halfway through doing the stuff I said I'd do to the
current draft and sending a diff.

			       _MelloN_

Date: Fri, 30 Mar 2001 01:36:36 +0300 (EEST)
From: =?iso-8859-1?Q?Martin-=C9ric_Racine?= <[email-masked]>
To: [email-masked]
Subject: DHCPNOGO
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On Wed, 28 Mar 2001, Ted Lemon wrote:

> DHCP server will just ignore a DHCPDISCOVER if it doesn't
> want to offer an address or doesn't have an address to offer.

>From an end-user's perspective, an obvious to-do for the DHCP
specification itself:

* Add a DHCPNOGO message to acknowledge a received DHCPDISCOVER,
  in the event of a refusal or unability to offer an address.

This would make it easier for end-users to rest assured that
their configuration is not messed, they just cannot "login" for
one reason or another.  It would clear a lot of doubts, in any
event of a failure to connect.

-- 
Martin-Éric Racine, IT Consultant * http://funkyware.atari.org/  
* May the Funk be with Q! * Author of the Atari TT030 Homepage.

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