Re: LL70: Use of the term "valid"

Because of the lack of subordination betweeen the "and" and the "or"
conjuctions, a programmer may interpret the text differently from a
marketeer.  And I'm not sure which version is "right", so wording
clarification I believe is necessary.

Philip's change removes this issue but doesn't fix my implementation
question.

Just to clarify my understanding, If the reachability test described in
DNAv4 is skipped, or fails, then IPv4LL can't have a "valid" address, simply
it will have a "routable" address.  In that event, I may assign an IPv4LL
address additionally on that interface, right?

Best regards

Jim Busse

----- Original Message ----- 
From: "Philip Nye" <[email protected]>
To: "Zeroconf Working Group" <[email protected]>
Sent: Tuesday, May 18, 2004 1:34 PM
Subject: Re: LL70: Use of the term "valid"


> From: "Peter Johansson" <[email protected]>
> At 09:47 AM 5/18/2004 -0700, Bernard Aboba wrote:
>
> >"A "valid routable address" is a routable address which is either
> >statically assigned or whose lease has not expired and that passes the
> >reachability test described in section 2 of "Detection of Network
> >Attachment (DNA) in IPv4" [DNAv4]."
>
> I would go the extra step and say: "A routable address is an address that
> is either statically assigned or whose lease has not expired and that
> passes the reachability test described in section 2 of "Detection of
> Network Attachment (DNA) in IPv4" [DNAv4]."

If this change is made, we are back to square one - the protocol depends on
the definition of a routable address and that definition depends on the
reference [DNAv4] which is therefore normative - and is problematic because
it is an unapproved draft.

I think that the use of "valid" conveys meaning because it helps people
grasp the idea that a host may have been configured with an address which
was previously valid but although still configured, is no longer useable
because the network has changed (e.g. the host moved to a new network). This
is a common case and there is often good reason not to simply unconfigure
that address because the host may soon be moved back to a context in which
it is valid - meanwhile assigning an IPv4LL address provides some
connectivity.

The validity of a configured address is difficult to establish because the
context in which it is intended to operate or becomes invalid can vary.
Therefore I think that all we can do is explain the concept and present the
DNAv4 reachability test as a useful example (informative) rather than a
definition (normative) of validity.

I suggested alternative text in an earlier email.

> Please also note the grammatical correction, "which" to "that".

I would dispute that English grammar is so clear cut. In this context "that"
or "which" both seem acceptable and either conveys the meaning well so I can
happily accept your ammendment - or not.

Philip