Proposed text for the concatenation

["Mannie, Eric" <Eric.Mannie@ebone.com>]

Dear All,

I am pleased to see so many people discussing so much on these mailing
lists, but now as an editor of draft-ietf-ccamp-gmpls-sonet-sdh-00.txt I
would like to make some progress.

Please, carefully read the following text that clarifies the contiguous
concatenation part of the draft and that introduces one simple new
concatenation type.

"This field indicates the type of SONET/SDH contiguous concatenation to
apply on the Elementary Signal. It is set to zero to indicate that no
contiguous concatenation is requested (default value). The values are
defined in the following table:

       Bits   Contiguous Concatenation Type
      -----   ----------------------------------
       000     No contiguous concatenation requested
       001     Standard contiguous concatenation
       010     Arbitrary contiguous concatenation
       011     Flexible arbitrary contiguous concatenation
      others   Vendor specific concatenation types

Standard contiguous concatenation refers to the contiguous concatenation as
it is defined in SDH G.707 and SONET ANSI T1.105. Arbitrary contiguous
concatenation relaxes the limitations of these standards in terms of the
location where a contiguous signal can start, and in terms of the number of
concatenated VC's/SPE's that can compose this signal.

Flexible arbitrary contiguous concatenation is an optimisation of the
arbitrary contiguous concatenation that allows to "inverse multiplex" a
contiguously concatenated signal on a per multiplex section/line basis. In
order to be effectively used, an upstream node must indicate that its
supports this feature to its immediate downstream node, using the CCT field.
The downstream node can in that case use that feature and return a list of
labels, one for each element of the "inverse multiplex"; instead of one
single label indicating the beginning of the contiguous signal.

The three types of contiguous concatenation defined here before defines
indeed a hierarchy of flexibility in the contiguous concatenation. If
selected, the flexible arbitrary contiguous concatenation, indicates that
any of the three types of contiguous concatenation can be chosen by the
downstream node. It is up to the downstream node to choose the one that it
wants to use. The upstream node, when receiving the labels from the
downstream node, may accept or refuse what was proposed."

Please send me your technical comments about the technical correctness of
this text only. Please, delay discussions about the usefulness of these
features and the way to implement them to another time. What is important is
that each feature works. Your profile, implementation, or configuration
should determine what you like and what you want to support, not this
signalling.

Take your time to read the text and to answer, it is 10PM in my time zone
and I will leave my office. I'll be back on Monday morning to read your
answers.

Many thanks to all of you and have a nice week-end.

Kind regards,

Eric

Eric Mannie
Technology & Standards Strategy Manager
Network Engineering Strategy
EBONE

Terhulpsesteenweg 6A
1560 Hoeilaart - Belgium

Tel:    +32 2 658 56 52
Mobile: +32 496 58 56 52
Fax:    +32 2 658 51 18
E-mail: eric.mannie@ebone.com