Re: Doubt in draft ccamp-gmpls-sonet-sdh-00.txt

[Maarten Vissers <mvissers@lucent.com>]

Manoj,


manoj juneja wrote:
> 
> Marteen,
>          Agreed, As per G.707, STM-64 consist of 64 VC-4 signals. I
> have one doubt here.  I want to discuss two cases in where two signals
> viz. VC-4-3c (contiguously concatenated signals) and VC-4-3v (virtually
> concatenated signals) have to be allocated to satisfy the two Label
> Request/Path messages.

Let's use a defined contiguous concatenated signal instead of the
undefined VC-4-3c; i.e. let's make the example with VC-4-4c and VC-4-4v.


> In case of VC-4-3c, do I have to allocate the contiguous VC-4s (viz.
> say 4th, 5th and 6th and not 10th, 20th and 30th) ? 

Contiguous concatenation implies per G.707 the use of X contiguous
timeslots to transport a VC-4-Xc. For the case of VC-4 these timeslots
are really contiguous. Which timeslots to use for a VC-4-Xc
(X=4,16,64,256) is defined in section 7/G.707 (10/2000). Subsection
7.3.2.3/G.707 specifies explictly the columns to use for the case of a
VC-4-4c in a STM-64. E.g. for the case the VC-4-4c is transported via
address (1,2,0,0), columns 5, 6, 7 and 8 of the STM-64 are the first 4
columns in which the VC-4-4c (1,2,0,0) is transported. The rest of this
VC-4-4c (1,2,0,0) is transported in groups of 4 contiguous columns
interspaced by 60 columns.

Please be aware that for the case of a STS-Xc, groups of X/3 columns are
contiguous in time. E.g. for the case of a STS-3c at (1,2,4,0) the first
column is STM-64 column 8, the 2nd column is column 72 and the 3rd
column is column 136.

> If I allocate the
> contiguous signal, does this mean in this case I have to pass only one
> label corresponding to the multiplexing position of 4th VC-4 (Lowest
> one) and other VC-4s will be derived by the receiving end from the
> lowest signal.

You have to pass the position of the 1st time slot which is occupied by
the VC-4-4c signal. In the case of the example this is number 5.

> 
> In case of contiguous concatenation, Can the contiguous VC-4 signals
> span the AUG-Xc in STM-N [ like STM-64 consist of AUG-64. Say it
> consist of 4 VC-4-16c.

An AUG-Xc doesn't exist. A VC-4-Xc (X=4,16,64,256) fits exactly the
AUG-X. E.g. in a STM-64 there is one AUG-64. This AUG-64 can contain
either one AU-4-64c, or four AUG-16's. Each of the AUG-16's can contain
either one AU-4-16c, or four AUG-4's. Each AUG-4 can contain either one
AU-4-4c or four AUG-1's. Each AUG-1 can contain either one AU-4 or three
AU-3's.

A VC-4-16c is transported via a AU-4-16c. Within a STM-64, VC-4-16c
signals can be transported via addresses (1,0,0,0), (2,0,0,0), (3,0,0,0)
or (4,0,0,0). Refer to section 7.3.2.4/G.707.

> If I have to allocate 20 VC-4s in contiguous
> concatenation, can I span VC-4s allocation across the AU-4-16cs  ?

Contiguous concatenation defined in G.707 doesn't support VC-4-20c. This
would only be supported by the proprieraty arbitrary concatenation. In
this case the VC-4-20c will be transported in a AU-4-20c.

> 
> In case of virtual concatenation, Can I allocate non-contiguous signals
> (viz. 10th, 20th, 30th) ? 

Virtual concatenation (e.g. VC-4-4v) as defined by G.707 allows you to
transport the four VC-4 signals via either one STM-N signal, or via two
STM-N signals, or via three STM-N singals or via four STM-N signals. 

For the case more than one (e.g. Y) of the X VC-4 signals in the VC-4-Xv
signal is transported via the same STM-N signal, Y arbitrary selected
AU-4 timeslots can be used; i.e. those timeslots may be contiguous or
non-contiguous.

GMPLS doesn't support this G.707 feature completely. GMPLS adds the
restriction that all X VC-4 signals within the VC-4-Xv must be
transported via the same STM-N signal. :-(
Essentially, GMPLS is not suited to setup a VC-4-Xv; VC-4-Xv signals
have to be setup via the management plane due to this restriction.

> In this case I have to pass 3 labels
> corresponding to each VC-4 position in the multiplexing hierarchy.

For a VC-4-3v you have to pass a generalised label including 3 labels in
the label field.

> Does this hold true for arbitrary concatenation also ?

Arbitrary contiguous concatenation is an extension of contiguous
concatenation, allowing X to be any value in the range 1 to N. It has
the same characteristics as contiguous concatenation, i.e. contiguous
timeslots are used. As such, only one label has to be transmitted in the
label field.

Regards,

Maarten









> 
> Please clarify.
> 
> Regards,
> manoj.
> 
> >From: Maarten Vissers <mvissers@lucent.com>
> >To: manoj juneja <manojkumarjuneja@hotmail.com>
> >CC: Eric.Mannie@ebone.com, ccamp@ops.ietf.org
> >Subject: Re: Doubt in draft ccamp-gmpls-sonet-sdh-00.txt
> >Date: Wed, 20 Jun 2001 03:46:04 +0200
> >
> >Manoj,
> >
> >A STM-64 doesn't consist of 64 STM-1s. Instead, a STM-64 may carry 64
> >VC-4 signals. Instead of 64 VC-4 signals, a sTM-64 may carry a mix of
> >VC-3, VC-4, VC-4-4c, VC-4-16c signals or a single VC-4-64c signal (refer
> >to G.707).
> >
> >A VC-4-16c signal can be transported in either one of the four AU-4-16c
> >tributary slots: (1,0,0,0), (2,0,0,0), (3,0,0,0) or (4,0,0,0); refer to
> >7.2.3.4/G.707.
> >
> >Regards,
> >
> >Maarten
> >
> >manoj juneja wrote:
> > >
> > > Hi Eric,
> > >           Thanks for the reply. I have one more doubt :
> > >
> > > A STM-64 interface consist of 64 STM-1s that are byte interleaved. If
> > > I have to allocate a signal VC-4-16c (unstructured VC-4s) means CCT
> > > with value 1 (standard contiguous concatenation), NCC as 16, NVC as 0,
> > > MT as 1, T as 0 to a VC-4 elementry signal. Does this mean, I have to
> > > allocate contiguous VC-4s in STM-64 link.
> > > Say if I allocate 16 VC-4s as 10th VC4 --> 25th VC-4 on STM-64 link.
> > > Then the {SUKLM} would be {s=10, U=1, K=1, L=0, M=0} (lowest signal)
> > > i.e. only one label will be passed in RESV/Label Mapping message. The
> > > receiving node will drive the subsequent labels from this onwards.
> > >
> > > In case of arbitrary or virtual concatenation, Can I allocate non
> > > -contiguous signals from a link ? The label corresponding to each
> > > arbitrary or virtually concatenated signal will be passed in
> > > RESV/Mapping message.
> > >
> > > If I have a STM-64 interface configured, and no signal is allocated yet
> >from
> > > the link.
> > > If I have to allocate a signal STM-3c-7v (virtual concatenation of 7
> > > STM-3c), Can I allocate the whole signal from this link ?
> > >
> > > Does this mean I have to allocate 21 STM-1s out of 64 STM-1s and I have
> >to
> > > pass 7 labels in RESV/Mapping message [ {1,0,0,0,0}, {4,0,0,0,0},
> > > {7,0,0,0,0}, {10,0,0,0,0}, {13,0,0,0,0}, {16,0,0,0,0}, {19,0,0,0,0} ].
> > >
> > > Does this mean that each STS-3c in STM-3c-7v should be contiguous ?
> > >
> > > Please tell me if my understanding is correct.
> > >
> > > Regards,
> > > manoj.
> > >
> > > Regards,
> > > manoj.
> > >
> > > >From: "Mannie, Eric" <Eric.Mannie@ebone.com>
> > > >To: 'manoj juneja' <manojkumarjuneja@hotmail.com>, ccamp@ops.ietf.org
> > > >Subject: RE: Doubt in draft  ccamp-gmpls-sonet-sdh-00.txt
> > > >Date: Tue, 19 Jun 2001 10:02:56 +0200
> > > >
> > > >Hello Manoj,
> > > >
> > > >The virtual concatenation is indicated in a separate field (NVC). The
> > > >reason
> > > >is to allow to code the virtual concatenation of contiguously
> >concatenated
> > > >signals (like the virtual concatenation of several STS-3c's.
> > > >
> > > >Kind regards,
> > > >
> > > >Eric
> > > >
> > > >-----Original Message-----
> > > >From: manoj juneja [mailto:manojkumarjuneja@hotmail.com]
> > > >Sent: Tuesday, June 19, 2001 3:03 AM
> > > >To: ccamp@ops.ietf.org
> > > >Subject: Doubt in draft ccamp-gmpls-sonet-sdh-00.txt
> > > >
> > > >
> > > >Hi,
> > > >
> > > >      I have a doubt in draft ietf-ccamp-gmpls-sonet-sdh-00.txt :
> > > >
> > > >   The CCT field can have values no concatenation, standard
> > > >concatenation, arbitrary, vendor specific.
> > > >But why can't virtual concatenation ? It was there in original draft.
> > > >But in the exmaples section for SDH/SONET signals, it is shown that a
> > > >virtually concatenated signal can be built using NVC field with CCT
> > > >value as 0. Please clarify the reason in doing so.
> > > >
> > > >Regards,
> > > >manoj.
> > > >
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