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LCAS and draft-mannie-ccamp-gmpls-lbm-tdm-00.txt

Eric, Dimitri,

I quickly scanned through your draft-mannie-ccamp-gmpls-lbm-tdm-00.txt. Doing so
I got the impression that you completely misunderstand the purpose of LCAS. LCAS
is NOT a signalling protocol. It is totally unrelated as such to control plane
based connection management (GMPLS, ASON) or network management based connection
management.

LCAS doesn't change the number of VC-n or ODUk trails in the network. If N
trails are set up between the A-end and Z-end, LCAS helps to hitless change the
number of trails being used for the actual transport of the client signal; i.e.
if X (X<N) trails are being used, and the operator/user wants to increase this
number to X+1 or shrink it to X-1, then LCAS coordinates the steps at the A-end
and Z-end to make sure the increase/reduction is performed hitless.

The steps to perform for the case X=N are:
A) X ==> X+1
   1) [Operator or User] request connection management [NMS or ASON/GMPLS]
      to setup additional VC-n/ODUk between SNP Pool (SNPP) associated with
      virtual concatenated endpoint at A-end and corresponding SNPP at Z-end
   2) connection management [NMS or ASON/GMPLS] commands LCAS controllers at
      A-end and Z-end to control the "addition" of the (X+1)th trail to the
      group of X trails ("Madd" command in G.7042) over which the client
      bitstream is transported
   3) LCAS at each end generates the ADD command (CTRL=ADD) and sends this
      to the receiver at the other end
   3) LCAS at A-end [Z-end] waits until connection is setup; the connection
      in one direction is setup if the Trail Signal Fail (TSF) condition at
      its end has cleared;
   4) LCAS communicates the TSF clearing to the other end ("MST=OK")
   5) once MST=OK is received, LCAS replaces CTRL=ADD by CTRL=EOS, and 
   6) at the start of the next VC-n/ODUk frame the client bitstream is
      distributed over X+1 (instead of X) VC-n/ODUk trails
   7) the receiver at the other end notices the change of CTRL=ADD to
      CTRL=EOS, and expects the client signal to be present on X+1 (instead
      of X) VC-n/ODUk trails at the begin of the next frame.


Example with X=3
================

The bits in a client bit stream with bits ...,1,2,3,4,... are distributed over
trails #1..#3 as follows:
	trail#1	trail#2	trail#3
			 ...
	  1-8	  9-16	 17-24
	 25-32	 33-40	 41-48
	 49-56	 57-64	 65-72
	 73-80   ...

When trail #4 is added, no client bits will be transported over it, until the
source has indicated this via the change of the control word CTRL=ADD =>
CTRL=EOS, and the new VC-n/ODUk frame begins. Assume that client bits
...,1,2,..,48 are transmitted in VC-n/ODUk frame "i", and frame "i+1" begins at
the moment client bit 49 is to be transmitted, then trail#4 will be used for the
transport of bits 73-80 and further:

	trail#1	trail#2	trail#3 trail#4
			...
	  1-8	  9-16	 17-24
	 25-32	 33-40	 41-48
	 49-56	 57-64	 65-72	 73-80
	 81-88	 89-96	 97-104	105-112
	113-120  ...



Regards,

Maarten


Internet-Drafts@ietf.org wrote:
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> 
>         Title           : GMPLS LSP Bandwidth Modification (LBM) for TDM
>                           Networks
>         Author(s)       : E. Mannie, D. Papadimitriou
>         Filename        : draft-mannie-ccamp-gmpls-lbm-tdm-00.txt
>         Pages           : 13
>         Date            : 15-Nov-01
> 
> This document defines how GMPLS can be used to dynamically modify
> the bandwidth of a TDM circuit. It focuses first on SONET/SDH and
> will cover G.709 in a next version.
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-mannie-ccamp-gmpls-lbm-tdm-00.txt
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