Re: [CCAMP] Draft Text for ITU-T - CCAMP Liason regarding Flexi-grid

Ramon Casellas <> Tue, 18 March 2014 10:42 UTC

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Date: Tue, 18 Mar 2014 11:42:28 +0100
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Subject: Re: [CCAMP] Draft Text for ITU-T - CCAMP Liason regarding Flexi-grid
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Dear all,

Thanks for your comments. Below a revised text, still open for discussion.

Personally, I am afraid i still don't fully grasp the last bullet, so 
please elaborate a bit more or re-formulate (Iftekhar, Rajan?)

[Editor: In my limited understanding:
- A NMC as bound to 1 OCh-P by definition of the in-force G.872.
- a Media channel may carry more than 1 OCh-P, but MC != NMC
- With a Optical Tributary Signal (OTS) there is a 1:1 mapping between 
- A particular case of OTS is an OCh-P
For my understanding, can a OTS group multiple OCh-P?]



In order to progress our work on the draft "Framework and Requirements 
for GMPLS based control of Flexi-grid DWDM networks" [1] and subsequent 
solution documents within the IETF CCAMP working group, we would like to 
receive your comments/clarification as follows (addressing ITU-T experts 
within Q6, Q12 and Q14):

.    Please comment on future changes regarding the values of nominal 
central frequency (NCF) granularity [NCFG, currently 6.25 GHz] and slot 
width granularity [currently 12.5 GHz], as defined in G.694.1. Is ITU-T 
considering alternative values (e.g. 3.125 GHz) in the foreseeable 
future? If yes, is it correct to assume, that the following always 
holds, w.r.t. slot width granularity and NCF granularity?
SWG = 2 * NCFG [Note: changes in these values may require additional 
code-points within encodings at control plane protocols]

.    Clarification on the maximum values of the slot width (m parameter) 
and the expected use cases (e.g. to cover the whole C band).
Knowing these values is required since it has an impact on their encoding.

.    Opinion / Clarification on the data plane "hitless" and "hitless" 
capabilities. Is ITU-T considering any hitless procedure, such as 
resizing / restoration of a network media channel (in terms of its 
frequency slot)? Examples of cases where hitless capabilities may be 
considered are:
o    Case 1: Recovery where the new network media channel uses a diverse 
o    Case 2: shrink / enlarge frequency slot width, invariant NCF (n)
o    Case 3: shift the NCF (n), maintaining the frequency slot width (m)

.    Clarification on the case where an OTUCn is carried by a 
(co-routed) group of network media channels which must be managed as a 
single entity (including set up, recovery, and hardware 
cross-connection). If this is in scope, what is the estimated 
availability of ITU-T Recommendation covering this new requirement?
[Note: CCAMP has considered so far the following requirement: "The 
control plane architecture SHOULD allow multiple media channels to be 
logically associated.  The control plane SHOULD allow the co-routing of 
a set of media channels logically associated". If ITU-T covers this new 
requirement, it may have an impact on the control plane representation 
and related procedures]

.    Current in-force G.872 recommendation defines that a media channel 
may carry more than one OCh-P signal. It also defines that a network 
media channel is a specific use of media channel with a single OCh-P.  
May a network media channel be defined as associated with more than one