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Re: Proposed response to the Liaison Statement on LMP Link Verification

Please find my comment in-line.

Dieter



John Drake wrote:
Snipped ...

- To what extent do we wish to deploy this kind of technology over
existing SONET/SDH networks? I think that many operators are interested
in deploying ASON/GMPLS technology over a portion of the capacity of
their existing transport networks. As a result, it is useful to look
at what is required for "peaceful coexistance" of this technology with
other traffic. This is what has motivated in G.7714.1 to use the
"distinguishing character" so that various termination and NIM functions
can tell the difference between a message used for discovery/connectivity
verification and a normal trace identifier. I am not convinced by
arguments such as "you will never see these in the same network" or
"the specific scenario is such that the wrong TT function or NIM
function will never see this message". You can never quite tell how
someone will connect things or use a particular feature, and it seems
like a far more robust approach to choose a format where it is always
possible to distinguish between the various possible uses of the same
bytes.

db: Note, to clarify, G7714.1 requires all new G7714.1-aware transport equipment, both terminations and intermediate equipment. And for operators, "turning-off" of legacy intermediate NIMs is not an option (proposed in G7714.1), as the investment in intermediate NIMs is not for 24/7 entertainment of our field staff. G7714.1 does not "peacefully coexist". One ITU operator suggested using a different byte than Jx based on this concern with G7714.1. Whereas, LMP requires GMPLS-aware transport equipment. And LMP provides two options depending on support by legacy equipment (in-band, correlation). For either G7714.1 or GMPLS LMP, an operator chooses equipment configurations/options based on their application. New applications/new equipment (no free lunch;-)). No different from today's operations. And the two options (in-band, correlated) provided by LMP support two different use scenarios, including use of legacy NIMs. As discussed for G7714.1, Q9 needs to evaluate the equipment support scenarios.
---end of comment---



JD:  I just wanted to second Deborah's comment.  The LMP test procedure
is used to exchange GMPLS control plane identifiers for the purpose of
LSP signalling.  If the trace correlation transport mechanism is used,
the existing SDH/SONET transport plane Jx bit pattern is transported in
the LMP Test procedure messages, i.e., in the GMPLS control plane.  This
allows two nodes, node 1 and node 2, to build the following association:

{Node 1's GMPLS ID and Jx bit pattern for link x, Node 2's GMPLS ID and
and Jx bit pattern for link x}


When you are saying that LMP is used to set up the proper TTI
(Jx pattern) between each pair of neighboring nodes along a path
during the LSP/connectionestablishement process (in your words:
LSP signalling), this should in my opinion be done via signaling
(e.g. RSVP)


This  means that it is 100% compatible with existing SDH/SONET equipment,
which is not a claim that G.7714.1 can make.  Note also that this is clearly
spelled out in the draft and has been mentioned in e-mail several times.


May I kindly remind you that G.7714.1's scope is layer adjacency
discovery. Setting up the TTI along a path is outside the scope
of G.7714.1. Discovery is used to determine the relationships of
link end points (CP-to-CP relationships) between two adjacent
nodes - depending on the chosen architecture it may also be possible
to determine the related date-plane-to-control-plane relationships
(if the Discovery Agent and the Connection Controler conincide on
both sides of the link which is a special case - sorry for using
the ASON terminology here)



Thanks,

John