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RE: [CCAMP] Gen-ART review of draft-ietf-ccamp-flexi-grid-fwk-05 - Nits/editorial items

2015-08-04 20:35:45
Hi Fatai,


I think the amount of frequency in use is exactly the same value of the slot 
width (ie., m*SWG). Please see the formula:



Frequency slot = [(central frequency) - (slot width)/2] ~[(central frequency) 
+ (slot width)/2]

That was not obvious to me in reading the draft.

As an alternative to Adrian's new sentence, could you add that formula to the 
draft?

Thanks,
--David

From: Fatai Zhang [mailto:zhangfatai(_at_)huawei(_dot_)com]
Sent: Tuesday, August 04, 2015 9:08 PM
To: Black, David; adrian(_at_)olddog(_dot_)co(_dot_)uk; 
fu(_dot_)xihua(_at_)zte(_dot_)com(_dot_)cn; 
daniele(_dot_)ceccarelli(_at_)ericsson(_dot_)com; 
ihussain(_at_)infinera(_dot_)com; 'General Area Review Team'
Cc: ccamp(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org
Subject: RE: [CCAMP] Gen-ART review of draft-ietf-ccamp-flexi-grid-fwk-05 - 
Nits/editorial items


Hi Adrian and David,



Thanks for your comments.



I just have one comment for clarification on the following proposal:



I think the original text is correct, so it is not necessary to add the last 
sentence in the "NEW'.



I think the amount of frequency in use is exactly the same value of the slot 
width (ie., m*SWG). Please see the formula:



Frequency slot = [(central frequency) - (slot width)/2] ~[(central frequency) + 
(slot width)/2]



In addition, I think some people might be confused by Nominal Central Frequency 
Granularity (which is 6.25) and Slot Width Granularity (which is 12.5).





================================================================================================

OLD

   o  Slot Width: The slot width determines the "amount" of optical

      spectrum regardless of its actual "position" in the frequency

      axis.  A slot width is constrained to be m x SWG (that is, m x

      12.5 GHz), where m is an integer greater than or equal to 1.

NEW

   o  Slot Width: The slot width determines the "amount" of optical

      spectrum regardless of its actual "position" in the frequency

      axis.  A slot width is constrained to be m x SWG (that is, m x

     12.5 GHz), where m is an integer greater than or equal to 1.

      The slot width defines the amount of spectrum in use on

      each side of the central frequency, thus the amount of

      frequency in use is actually twice the value of the slot width.



That definitely helps.









Best Regards



Fatai





-----Original Message-----
From: Black, David [mailto:david(_dot_)black(_at_)emc(_dot_)com]
Sent: Tuesday, August 04, 2015 10:30 PM
To: 
adrian(_at_)olddog(_dot_)co(_dot_)uk<mailto:adrian(_at_)olddog(_dot_)co(_dot_)uk>;
 Fatai Zhang; 
fu(_dot_)xihua(_at_)zte(_dot_)com(_dot_)cn<mailto:fu(_dot_)xihua(_at_)zte(_dot_)com(_dot_)cn>;
 
daniele(_dot_)ceccarelli(_at_)ericsson(_dot_)com<mailto:daniele(_dot_)ceccarelli(_at_)ericsson(_dot_)com>;
 ihussain(_at_)infinera(_dot_)com<mailto:ihussain(_at_)infinera(_dot_)com>; 
'General Area Review Team'
Cc: ccamp(_at_)ietf(_dot_)org<mailto:ccamp(_at_)ietf(_dot_)org>; 
ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>; Black, David
Subject: RE: [CCAMP] Gen-ART review of draft-ietf-ccamp-flexi-grid-fwk-05 - 
Nits/editorial items



Adrian,



Thanks for the response - this note contains the follow-ups on nits/editorial

items.  All of these are nits or editorial, and hence I defer to the editors'

discretion on what (if anything) to do about them.  The two suggestions for

text revisions in your response will definitely improve the draft, IMHO.



Thanks,

--David



-----Original Message-----

From: Adrian Farrel [mailto:adrian(_at_)olddog(_dot_)co(_dot_)uk]

Sent: Monday, August 03, 2015 1:38 PM

To: Black, David; 
zhangfatai(_at_)huawei(_dot_)com<mailto:zhangfatai(_at_)huawei(_dot_)com>; 
fu(_dot_)xihua(_at_)zte(_dot_)com(_dot_)cn<mailto:fu(_dot_)xihua(_at_)zte(_dot_)com(_dot_)cn>;

daniele(_dot_)ceccarelli(_at_)ericsson(_dot_)com<mailto:daniele(_dot_)ceccarelli(_at_)ericsson(_dot_)com>;
 ihussain(_at_)infinera(_dot_)com<mailto:ihussain(_at_)infinera(_dot_)com>; 
'General Area Review

Team'

Cc: ccamp(_at_)ietf(_dot_)org<mailto:ccamp(_at_)ietf(_dot_)org>; 
ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>

Subject: RE: [CCAMP] Gen-ART review of draft-ietf-ccamp-flexi-grid-fwk-05



Hello David,



Responding as a contributing author who wants to see this work move forward

promptly...



Many thanks for taking the time to review.



[... snip ...]



Nits/editorial comments:



Section: 3.2.1 - Editorial suggestion: Changing "+" -> "+/-" in the

formula for nominal central frequency and re-defining n as a

non-negative integer would be slightly clearer.



This is something you'd need to take up with the ITU-T, I think.

We don't want to change the formulae in common use where the data plane is

defined.



Ok, proof by (ITU-T) authority wins here.



p.6 - please state that slot width is +/- wrt nominal central frequency.



Ah, took me a moment to see what you mean.

Yes, this could be clarified with



OLD

   o  Slot Width: The slot width determines the "amount" of optical

      spectrum regardless of its actual "position" in the frequency

      axis.  A slot width is constrained to be m x SWG (that is, m x

      12.5 GHz), where m is an integer greater than or equal to 1.

NEW

   o  Slot Width: The slot width determines the "amount" of optical

      spectrum regardless of its actual "position" in the frequency

      axis.  A slot width is constrained to be m x SWG (that is, m x

      12.5 GHz), where m is an integer greater than or equal to 1.

      The slot width defines the amount of spectrum in use on

      each side of the central frequency, thus the amount of

      frequency in use is actually twice the value of the slot width.



That definitely helps.





p.8 - Fig 4 could use a bit more explanation - the two frequency

slots occur at different points along the path.



Maybe...



OLD

   o  Effective Frequency Slot [G.870]: The effective frequency slot of

      a media channel is that part of the frequency slots of the filters

      along the media channel that is common to all of the filters'

      frequency slots.  Note that both the Frequency Slot and Effective

      Frequency Slot are local terms.

NEW

   o  Effective Frequency Slot [G.870]: The effective frequency slot of

      a media channel is that part of the frequency slots of the filters

      along the media channel that is common to all of the filters'

      frequency slots.  Note that both the Frequency Slot and Effective

      Frequency Slot are local terms.



      Figure 4 shows the effect of combining two filters along a channel.

      The combination of frequency slot 1 and frequency slot 2 applied to

       the media channel is effective frequency slot shown.

END



That also helps.



Nit: First nominal central frequency 'X' in Fig 5 needs to move 2

chars left.



I think it is one char :-)



Touche'



Section 4 - TE link term shows up w/o acronym expansion or definition.

Please define it before use.



Yes. Last line of section 4.



   This section provides a mapping of the ITU-T G.872 architectural

   aspects to GMPLS/Control plane terms, and considers the relationship

   between the architectural concept/construct of media channel and its

   control plane representations (e.g., as a TE link).



I don't understand how "e.g." defines "TE link".



Sections 4.2 and 4.3 - this may be my unfamiliarity, but it would have

helped to have some sort of heads-up at the start of the figures that

the top (non-GMPLS) portion of the figures prior to Figure 12 are

entirely in the optical domain.  Perhaps explaining what the two

planes are (and how they're realized/implemented) in Figure 8 would help.



Hmmm. I think the reader should be coming at this with the concepts of TE link

and LSR in their heads so that the mapping is clear.



Ok, chalk this one (and probably the previous one) up to me not being a

GMPLS expert.



Last paragraph on p.16: "trnaponders" -> "transponders".  Also, I saw

"transceivers" earlier - if that's the same concept, only one term

should be used.



While "transponder" is technically correct, using "transceiver" would be more

consistent.



Ok.



p.19 - Even after expanding acronyms, I don't understand this sentence:



   If two OTSis must be

   switched to different ports, it is better to carry them by different

   FSC channels, and the media layer switch is enough in this scenario.



A sentence or two explaining what an "FSC channel" is earlier in that

paragraph would help.



p.21, 1st para:



   messages, and a specific frequency slot can be requeste on any



s/requeste/requested



p.21:



   In GMPLS the requested effective frequency slot is represented to the

   TSpec present in the Path message, and the effective frequency slot

   is mapped to the FlowSpec carried in the Resv message.



I believe those are RSVP-TE messages - that should be stated.



p. 22:



   d.  n can change, but m needs to remain the same along the path.

       This ensures that the effective frequency slot remains valid, but

       allows the frequency slot to be moved within the spectrum from

       hop to hop.



In full generality, that may require the ability to shift or convert a

frequency slot, which is a concept that doesn't appear to occur in the

draft prior to this point.



Penultimate paragraph of page 21.



Ok.



Figures 15 and 16 need their variables (e.g., m_a, FSb) somehow

labelled or explained



After Figure 16, the switch to the EFS acronym is a surprise, given

the extensive prior usage of the spelled-out term.  This paragraph

contains all uses of the EFS acronym - I suggest removing that acronym

and spelling out the term.



Section 4.6: I don't understand why this sentence is in the middle of

the paragraph - it doesn't seem to describe an example of different

slot width granularities:



   Consider a node with an application where the nominal

   central frequency granularity is 12.5 GHz and where slot widths are

   multiples of 25 GHz.



I'd suggest removing it.



5.1.1. What is L-band?  This is the first time it's mentioned.



idnits 2.13.02 didn't find anything that needs attention.



Many thanks,

Adrian