[Nml-wg] Serial compound relations: "last" call on concepts, part 1

[Jason Zurawski]

On 2/1/11 8:24 PM, Freek Dijkstra wrote:
> Hi,
>
> At the previous call I was assigned the following work item (someone my
> absence from the call put me on the "I volunteer" list; at least that's
> what I was told afterwards :~O )
>
>> * Serial Compound Relations Syntax
>> Freek put this on the agenda to close our discussion we had on the
>> mailinglist. We had a too small group to make a decision on this.
>> It would also help if we had a summary of the discussion until right
>> now. Freek, could you provide that?
>
> I have not caught up with all yet, but like some sort of workgroup last
> call for the following decision:
>
> There are three ways to describe a serial compound relation (thus the
> segmentation of a end-to-end link on a single layer)
>
> 1. It should be possible to say that a link A is a segment of another
> link E.
> 2. It should be possible to say that a link A has sink port X, and port
> link has source port X, meaning that link A is directly connected to link B.
> 3. It should be possible to say that a link A is followed by the "next"
> link B.
> 4. It is possible to say that a link A is the "first" link (segment) of
> a link E (the end-to-end link), and it is possible to say that a link D
> is the "last" link (segment) of a link E.
> 5. We only use the concept of "links", not of "segments" or "end-to-end
> link", it is the _relation_ that determine if some link is a "segment"
> of another link or not.
>
> (Note that this explicitly chooses the "first", "next", "last" relations
> as proposed by Aaron, not the numbered (1,2,3,...) relations as proposed
> by Freek.)
>
> With the following additions:
>
> Ad 2. In case 2, links that are cross connects within a device MUST be
> listed.
> Ad 3. In case 3, cross-connect links MAY/MUST(?) be skipped, meaning
> that in the situation:
>   - sink of link A is port X
>   - source of link C is port X
>   - link C is of type "crossconnect"
>   - sink of link C is port Y
>   - source of link B is port Y
> then one can (MUST? MAY?) say that:
>   - the "next" link following link A is link B
> instead of:
>   - the "next" link following link A is link C (of type crossconnect)
>   - the "next" link following link C is link B
>
> There is more to say on this topic (e.g. the above does not discuss
> syntax in any way), but the above is what I have seen in proposals and
> examples. I now like to ratify or reject this by the working group.
>
> Please mail your comment (even if it is just "OK") within three weeks.
> We particular like input on addendum 3. (is that a "MAY" or a "MUST"?)

Tentative OK, I would like to see a concrete example personally.

-jason