Subject: [dhcwg] DHCP_DECLINE question

From: "Burcak Beser" <[email-masked]>
Date: Wed, 27 Feb 2002 15:04:30 -0800

I have a question regarding the use of DHCP_DECLINE message. If the client is choosing a valid DHCP_OFFER using contents of the returned options, and the DHCP SERVER changes the contents of the options while sending the DHCP_ACK message, is it acceptable for client to use DHCP_DECLINE? (The RFC 2131 states that DHCP_DECLINE is issued when the IP address in use.)

In other words when a DHCP_DECLINE is received by the DHCP SERVER does this mean that the client detected that the IP address is already used by another entity? 

-burcak

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From: "Steve Gonczi" <[email-masked]>
Date: Thu, 28 Feb 2002 11:49:09 -0500

I am not sure what you mean by "changes the contents of the options".

The RFC only speaks of the client declining the ACK because of
an address conflict.

Conceptually I see no problem with the client declining for some other
reason.  E.g.: the client examined the option list
it received, and did not like one/some of them.

The RFC says:

"5. The client receives the DHCPACK message with configuration
     parameters.  The client SHOULD perform a final check on the
     parameters (e.g., ARP for allocated network address)"

Advocating such parameter check implies that the check could possibly
fail, and could fail for some reason other than an addres conflict.

PS.
There is a remote possibility, that some server implementation
takes the DECLINE to mean that there IS an address conflict,
and blacklists the address.

/sG

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of Burcak
Beser
Sent: Wednesday, February 27, 2002 6:05 PM
To: [email-masked]
Cc: [email-masked]
Subject: [dhcwg] DHCP_DECLINE question

I have a question regarding the use of DHCP_DECLINE message. If the client
is choosing a valid DHCP_OFFER using contents of the returned options, and
the DHCP SERVER changes the contents of the options while sending the
DHCP_ACK message, is it acceptable for client to use DHCP_DECLINE? (The RFC
2131 states that DHCP_DECLINE is issued when the IP address in use.)

---

From: Ted Lemon <[email-masked]>
Date: Thu, 28 Feb 2002 10:05:03 -0700

> it received, and did not like one/some of them.

This is a giant can of worms that we don't want to open.   Right now, I 
think that DHCP Decline means "this address is in use by some other client.
"   Changing the semantics of DHCP Decline right now is a bad idea.   If we 
need a message that says "I don't like this response, and won't use it," 
then we should invent a new message.   DHCP Release would do the job, 
except that it doesn't indicate that the client is rejecting the address - 
just that the client isn't going to use it.