WG ACTION: 2 weeks to discuss [LL67] Fix clause which forbids routable to LL communication

Please post discussion of this issue to the mailing list over the 
next two weeks
ending May 18, 2004.  In order to accept this issued, we will need a strong WG
consensus given that this is very late in the process.

Please see http://www.drizzle.org/~aboba/ZEROCONF/issues.html for a list of
current issues and their status.

[LL67]

Description of Issue:		Fix clause which forbids routable to 
LL communication
Submitter Name:                 Stuart Cheshire
Submitter Email Address:        [email protected]
Date first submitted:           04 May 04
Reference:
Comment Type ['t'ech|'e'dit]:	t
Prio ['S' Must|1 should|2 may]:	S
Section:			6.2
Rationale/Explanation:
Lengthy Description:

[Stuart]

>    IPv4 Link-Local addresses MUST NOT be forwarded via an application
>    protocol (for example in a URL), to a destination which is not Link-
>    Local, on the same link.  This is discussed further in Section 2.9
>    and 3.

How about:
>    IPv4 Link-Local addresses MUST NOT be forwarded via an application
>    protocol (for example in a URL), to a destination which is not
>    on the same link.  This is discussed further in Section 2.9 and 3.

[Erik]

Your sentence means something entirely different than what is in the
document.  In your text host A with LL address a could send 'a' in an
application protocol to host B with a routable address.  In the current
document, this would not be allowed.  We want proper interaction
between hosts A and B with as few restrictions as possible without
disruptive consequences.  That is the fine line we've had to walk for
the past 5 years.  I personally prefer your wording (and its meaning) to
what the document currently says.  To open this up would require us to
go back to discussion, last calls, etc. however.

[Stuart]

As written, other places in the draft allow routable-to-LL communication,
but this "MUST NOT" prohibits that. A routable device can't send packets
to an LL device unless it knows the LL device's LL address, but how can a
routable device learn the LL device's LL address, if sending an LL
address to a non-LL destination address is prohibited?

[Erik]

This is clearly a technical revision we need to consider.  I agree
that we should make this change.

Requested Change:

Section 6.2, From:

>    IPv4 Link-Local addresses MUST NOT be forwarded via an application
>    protocol (for example in a URL), to a destination which is not Link-
>    Local, on the same link.  This is discussed further in Section 2.9
>    and 3.

To:

>    IPv4 Link-Local addresses MUST NOT be forwarded via an application
>    protocol (for example in a URL), to a destination which is not
>    on the same link.  This is discussed further in Section 2.9 and 3.