Subject: Re: Example email from vendor: Probe after cable connection or not?

From: Erik Guttman <[email-masked]>
Date: Tue, 03 Jun 2003 18:46:32 +0200

Since there has been no debate - I say we just accept the text
suggested by Stuart.

We will work this text into the revised section 2.2

2.2 Claiming a Link-Local Address

    After it has selected an address, a host MUST test to see if
    the address is already in use before beginning to use it. To be
    more specific, any time that a network interface transitions from
    an inactive to an active state, the host is in a position where
    it has no knowledge of what addresses may be currently in use on
    that link. Were it immediately to begin using an address which is
    already in use by some other host, this would be disruptive to that
    other host. For this reason, before using the address (e.g. using
    it as the source address in an IP packet, or as the Sender IP
    address in an ARP packet) a host MUST perform the probing test
    described below to achieve better confidence that using the address
    will not cause disruption. Examples of events that entail an
    interface becoming active include:

       * Reboot/startup
       * Wake from sleep (if network interface was inactive during
         sleep)
       * Bringing up previously inactive network interface
       * Ethernet hardware link-state change that indicates
         a cable was attached.
       * Association with a wireless base station.
       * etc.

    Note that a host MUST NOT perform this check periodically as a
    matter of course.  This would be a waste of network bandwidth,
    and is unnecessary due to the ability of hosts to passively
    discover conflicts, as described in Section 2.5.

Erik