Subject: Differences between LL18 proposed resolutions

From: Bernard Aboba <[email-masked]>
Date: Thu, 11 Sep 2003 06:55:02 -0700 (PDT)

Looking at the two proposed resolutions of LL18, here are the differences:

1. Mention of source address selection has been removed from 2.6.1 (the
sentence "For a multi-homed host, the decision as to which source address
to use is also more difficult").  It does seem somewhat relevant to
discuss this in 2.6.1 or 2.6.2.

2. The suggested "MUST ARP for the destination address" has been changed
to "SHOULD ARP".  My understanding was that MUST ARP was selected since
source address/interface selection and the desire to send the packet (as
opposed to dropping it) was presumed. I'd therefore suggest that MUST ARP
be put back.

3. Additional text on "ARP for everything" has been added. This text
appears to conflict with the desired multi-homing behavior, so I would
suggest that we rephrase it to say "In the case of a device with a single
interface and only a link-local address".  Also at the end of the
paragraph, we might add "For suggested behavior in multi-homed hosts, see
Section 3."

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From: "Philip Nye" <[email-masked]>
Date: Thu, 11 Sep 2003 21:44:42 +0100

> From: "Bernard Aboba" <[email-masked]>
>

I agree that Eric's text changes the sense slightly but think that he is
right and the text adequate. Eric's text implies that the selection of
interface is a complex issue, but once selected the host SHOULD use a
routable source address if one is available on that interface - subject to
the same caveats as for a single interface (existing connections, incoming
requests etc.)

> opposed to dropping it) was presumed. I'd therefore suggest that MUST ARP

I agree with Bernard here - if the packet is to be sent at all, then there
is no alternative but to ARP so "MUST" is appropriate. The alternatives of
dropping the packet or sending via a different interface is covered by the
revised text anyway.

Philip