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

[Ramon Casellas <[e-mail]>]

El 04/08/2015 a las 16:30, Black, David escribió:
> Adrian,
>
> Thanks for the response - this note contains the follow-ups on nits/editorial
> items.
>
>> -----Original Message-----
>> From: Adrian Farrel [mailto:[e-mail]]
>> Sent: Monday, August 03, 2015 1:38 PM
>>
>>
>>> Nits/editorial comments:
>>>
>>> Section: 3.2.1 - Editorial suggestion: Changing "+" -> "+/-" in the
>>> formula for nominal central frequency and re-defining n as a
(snip)
>>> Ok, proof by (ITU-T) authority wins here.
Ramon> No change here then.
>>> 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.
Ramon> as noted by Fatai, I think the second part of the "NEW" is 
incorrect. The slot width is always m*SWG. Do not confuse with NCF 
granularity
I am also reluctant to add Fatai formula Frequency slot = [(central 
frequency) - (slot width)/2] ~[(central frequency) + (slot width)/2]
since it is adding a new way of describing the slot in addition to the 
(n,m) pair via the start / end NCF.

In short, IMHO the slot width is the amount of optical spectrum (m*SWG) 
and the slot width is "centered" at its Nominal _Central_ Frequency (n). 
That is it, regardless of whether SWG and NCF granularity happen to be 
12.5 and 6.25

No changes here.

>
>>> 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.
Ramon> Changed to NEW. Also shifted the text "Frequency slot 1" of the 
figure a bit to the left to be
centered
>
>>> Nit: First nominal central frequency 'X' in Fig 5 needs to move 2
>>> chars left.
>> I think it is one char :-)
> Ramon> Changed, thanks.

> 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".
Ramon> Changed to

NEW
(e.g., as a TE link, as defined in [RFC3945].)
>>> 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.

Ramon> no changes

>
>>> 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.
Ramon> Changed to transceiver, thanks. Probably the typo caused it being 
missed in a S&R :)

> Ok.
>
>>> p.21, 1st para:
>>>
>>>     messages, and a specific frequency slot can be requeste on any
>>>
>>> s/requeste/requested
Ramon> changed, thanks.
>>>
>>> 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.
Ramon> Changed to "present in the RSVP-TE Path message (...) RSVP-TE 
Resv message.
Thanks

>>> 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.
Ramon> no changes.


>   
>>> Figures 15 and 16 need their variables (e.g., m_a, FSb) somehow
>>> labelled or explained
Ramon> Changed to
                          C B                A
           |Path(m_req)   | ^                |
           |--------->    | #                |
           |              | #                ^
-^--------------^----------------#----------------#--
Effective #              # #                #
FS n, m   # . . . . . . .#. . . . . . . . # . . . . . . . .# <-fixed
           #              # #                #   n
-v--------------v----------------#----------------#---
           |              | #                v
           |              |                # Resv  |
           |              |                v <------ |
           |              |                |FlowSpec(n, m_a)|
           |              | <--------|                |
           |              |  FlowSpec (n,  |
                 <--------|      min(m_a, m_b))
           FlowSpec (n,   |
             min(m_a, m_b, m_c))

             m_a, m_b, m_c: Selected frequency slot widths

and

                         C B                 A
           |Path(m_req)  ^ |                 |
           |--------->   # |                 |
           |             # ^                 ^
-^-------------#----------------#-----------------#--------
Effective #             # #                 #
FS n, m   #             # #                 #
           #             # #                 #
-v-------------v----------------#-----------------#--------
           |             | #                 v
           |             |                # Resv  |
           |             |                v <------ |
           |             |                |FlowSpec(n_a, m_a)
           |             | <--------|                 |
           |             |  FlowSpec (FSb [intersect] FSa)
                <--------|
          FlowSpec ([intersect] FSa,FSb,FSc)

           n_a: Selected nominal central frequencyfr by node A
           m_a: Selected frequency slot widths by node A
           FSa, FSb, FSc: Frequency slot at each hop A, B, C

>>> 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.
Ramon> done.
>>>
>>> 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.
Ramon> although sentence did try (badly) to describe a different slot 
widths (by default the values are 6.25 and 12.5) the sentence did not 
add value other than being a trivial example. Removed

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

The control plane architecture SHOULD allow for the support of
L-band (the wavelength range 1565 nm to 1625 nm) and S-band (the
wavelength range 1460 nm to 1530 nm).

also added

(...)  the entire C-band (the wavelength range 1530–1565 nm, which
corresponds to the amplification range of erbium doped fiber
amplifiers)



Many thanks
Ramon