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

2015-08-04 09:34:32
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; 
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

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