|
Hi David, I am not sure if it needs the formula or not, but I think you can get more information from Section 3.2.1.
It can be seen that a slot width is constrained to be m x SWG…., Slot Width Granularity (SWG) is 12.5 GHz, and Nominal Central Frequency Granularity
is 6.25GHz. Take Figure 3 as an example.
Note that the '--' represents the Nominal Central Frequency Granularity (NOT Slot Width Granularity)!! i.e., a couple of '--' forms the size of one SWG. Frequency Slot 1: slot width = 2*SWG=2*12.5=25GHz. Frequency Slot 2: slot width = 3*SWG=3*12.5=37.5GHz. Best Regards Fatai From: Black, David [mailto:david.black@xxxxxxx]
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, From: Fatai Zhang [mailto:zhangfatai@xxxxxxxxxx]
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----- 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@xxxxxxxxxxxx] > Sent: Monday, August 03, 2015 1:38 PM > To: Black, David;
zhangfatai@xxxxxxxxxx;
fu.xihua@xxxxxxxxxx; >
daniele.ceccarelli@xxxxxxxxxxxx;
ihussain@xxxxxxxxxxxx; 'General Area Review > Team' > Cc:
ccamp@xxxxxxxx;
ietf@xxxxxxxx > 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 |