Subject: Re: [dhcwg] DHCP_DECLINE question

From: Kim Kinnear <[email-masked]>
Date: Thu, 28 Feb 2002 12:26:03 -0500

At 06:04 PM 2/27/2002, Burcak Beser wrote:
>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.)

        No, it is not. See below.

>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? 

        Yes, and the implication (as well as the explicit
        direction) is that the DHCP server should not offer this
        IP address to this client or any other client for at
        least some time since it has been shown to be "unusable"
        for DHCP client allocation (because some client (or
        machine, maybe not a DHCP client) appears to be using it).

        From RFC2131.txt:

4.3.3 DHCPDECLINE message

   If the server receives a DHCPDECLINE message, the client has
   discovered through some other means that the suggested network
   address is already in use.  The server MUST mark the network address
   as not available and SHOULD notify the local system administrator of
   a possible configuration problem.

        If you don't like the IP address, you could use a
        DHCPRELEASE to give it back.  Of course, you may in that
        case be offered it next time, but you don't need to take
        the offer.

        If you just want to give it back, use DHCPRELEASE.

        If you want to give it back and be offered a different IP
        address from this server, that's a harder question, since
        the DHCPDECLINE implies that the address isn't usable.

        Cheers -- Kim

>-burcak
>
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