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

[Fatai Zhang <[e-mail]>]

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:[e-mail]]
Sent: Tuesday, August 04, 2015 10:30 PM
To: [e-mail]; Fatai Zhang; [e-mail]; [e-mail]; [e-mail]; 'General Area Review Team'
Cc: [e-mail]; [e-mail]; 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:[e-mail]]

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

> To: Black, David; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>;

> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; 'General Area Review

> Team'

> Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>

> 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