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draft-ietf-ccamp-gmpls-sonet-sdh-extensions-00.txt
Eric,
Going through some of the GMPLS SDH/SONET email, I came accross an unfinished
discussion on arbitrary contiguous concatenation. This issue is relevant for the
draft-ietf-ccamp-gmpls-sonet-sdh-extensions-00.txt document.
Let's me try to address this issue once more via a specific example:
Assume a OC-12 signal, which should carry a STS-3a and of which the lowest
signal is in the first timeslot. The question is now the timeslots carrying the
2nd and 3rd signal within the STS-3a. Is it (A) or (B) as shown below?
Time 111 111
Slot 123456789012123456789012...
(A) XXX XXX
(B) X X X X X X
And for the case of an OC-48 signal, are the STS-3a timeslots according (C) or
(D) below?
Time 111111111122222222223333333333444444444 11111111
Slot 12345678901234567890123456789012345678901234567812345678901234567..
(C) XXX XXX
(D) X X X X X
Regards,
Maarten
Maarten Vissers wrote:
>
> Eric,
>
> Let's discuss this issue during the IETF meeting in London. Being face to face
> its easier to illustrate that a STS-3c isn't using 3 physically contiguous
> timeslots.
>
> For the standard contiguous concatenation (including STS-3c) there are T1.105
> and G.707 defining the timeslots used. But there are no transport plane
> documents that define the timeslot allocation for arbitrary concatenation. I.e.
> is a STS-3a using physically contiguous timeslots or is it using the same
> timeslots a STS-3c would use?
> As the gmpls-sonet-sdh document is the first and only standard describing
> arbitrary concatenation, interworking is only guaranteed when it is unambiguous
> which timeslots are being used.
>
> Regards,
>
> Maarten
>
> "Mannie, Eric" wrote:
> >
> > Hello Juergen and Maarten,
> >
> > I don't understand the relationship between
> > draft-ietf-ccamp-gmpls-sonet-sdh-01.txt and the problem that you are talking
> > about.
> >
> > In addition, the IETF is not specifying any SDH/SONET interoperability (Not
> > at all in the GMPLS scope).
> >
> > Also, I am not sure to understand why the abstract (B, A) notation of G.707
> > (used to have a clearer specification, and not used (transported) in any
> > protocol as far as I know) could imply that contiguous time-slots are not
> > contiguous anymore ?
> >
> > The "Arbitrary" concatenation that you are speaking about is a contiguous
> > concatenation, time-slots are physically contiguous. I don't understand the
> > relevance of the SDH (B, A) notation in relationship with SONET in the
> > context of the IETF. Anyway, contiguous time-slots will stay physically
> > contiguous even if you see an issue with the SDH G.707 (B, A) notation
> > applied to SONET.
> >
> > Also, "flexible arbitrary concatenation" (whatever it is - everybody seems
> > to have a different understanding) is not part of
> > draft-ietf-ccamp-gmpls-sonet-sdh-01.txt.
> >
> > I guess also that this discussion is relevant for the ITU-T and/or T1X1, not
> > for the ccamp mailing list (of the IETF).
> >
> > Kind regards,
> >
> > Eric
> >
> > -----Original Message-----
> > From: Heiles Juergen [mailto:Juergen.Heiles@icn.siemens.de]
> > Sent: Tuesday, July 24, 2001 4:28 PM
> > To: 'Maarten Vissers'; ccamp
> > Cc: t1x1.5; q11/15
> > Subject: AW: [T1X1.5] arbitrary contiguous concatenation question
> >
> > Maarten,
> >
> > good point. Lets hear what the supporters of arbitrary concatenation have to
> > say.
> >
> > Juergen
> >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Maarten Vissers [mailto:mvissers@lucent.com]
> > > Gesendet: Dienstag, 10. Juli 2001 11:14
> > > An: ccamp
> > > Cc: t1x1.5; q11/15
> > > Betreff: [T1X1.5] arbitrary contiguous concatenation question
> > >
> > >
> > > 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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