arbitrary contiguous concatenation question

[Maarten Vissers <mvissers@lucent.com>]

All,

draft-ietf-ccamp-gmpls-sonet-sdh-01.txt defines signalling support for arbitrary
contiguous concatenation in appendix 3. Looking a bit more into this arbitrary
concatenation from the transport plane, I came across a question with respect to
the definition of "contiguous STS-1/AU-3 timeslots". Let me introduce this
question:

Figure 7-25/G.707 (10/2000) lists the AU-3 numbering (within an STM-4) as
follows

     Time          111
     Slot 123456789012123456789

	B 123412341234123412341...
	A 111122223333111122223...

AU-3 timeslots have a TimeSlot number and a (B,A) number, with TS1 associated
with (1,1) and TS12 associated with (4,3).

	Note - the figure in the pre-published version of G.707
	doesn't show the timeslot numbering in a correct manner.

and the AU-4 numbering is as follows (figure 7-24/G.707)

     Time
     Slot 123412341234123412341

	B 123412341234123412341...
	A 000000000000000000000...

An AU-4 [STS-3c] is as such essentially a "non-contiguous" concatenation of
AU-3s [STS-1s]; i.e. every 4th AU-3/STS-1 is use; e.g. AU-4 (2,0) uses AU-3
timeslots 2,6,10 [i.e. (2,1), (2,2), (2,3)].


If we define STS-1 contiguous concatenation, which timeslots are then used for
e.g. a STS-1-3c:
	i)  timeslots (1,1),(2,1) and (3,1) [TS1,TS2,TS3], or
	ii) timeslots (1,1), (1,2) and (1,3) [TS1,TS5,TS9]

Similarly, for the case of a STS-1-6c do we use:
	i)  (1,1), (2,1), (3,1), (4,1), (1,2) and (2,2) [TS1,TS2,TS3,TS4,TS5,TS6] or
	ii) (1,1), (2,1), (1,2), (2,2), (1,3) and (2,3) [TS1,TS2,TS5,TS6,TS9,TS10]


And which timeslots do we use for e.g. a STS-1-5c?


If this detail is not specified, interworking is not possible unless we include
the list of timeslots as we do with virtual concatenation (and as discussed for
flexible arbitrary concatenation).


Regards,

Maarten
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