Re: [CCAMP] WG Last Call on draft-ietf-ccamp-flexi-grid-fwk-03 and call for sheperd

[Ramon Casellas <[e-mail]>]

El 20/05/2015 a las 9:29, Jonas Mårtensson escribió:
>
> Hi Ramon,
>
> 4.8.4: bear in mind that 0 is not a positive integer, and it looks 
> like the definitions involving (2^n) and (2^m) are intended to include 
> the case where n/m is 0.
>
> Ramon> Changed for "n" to say "non-negative integer". For "m", I am 
> leaving it as positive integer, since m=0 would imply an empty 
> frequency slot.
>
> How do you figure that? Doesn’t
>
> <Available Slot Width Granularity> ::= (2^m) x 12.5GHz
>
> imply that the available SWGs start at 25 GHz if “m” is positive integer?
>

Hi Jonas,

True, I think you spotted an error; in any case there is significant 
room for confusion, and now I regret that the model in section 4.8.4 
uses "n" and "m" mixing the ITU-T definitions and the variables in the 
formulas themselves to describe granularities.

- The parameter m is defined by ITU G.694.1 "a slot width defined by: 
12.5 × m where m is a positive integer and 12.5 is the slot width 
granularity in GHz."
- The parameter n is defined 193.1 + n × 0.00625 where n is a positive 
or negative integer including  0, parameter to describe nominal central 
frequencies (for which n can be indeed negative).
- Unfortunately both are used to describe granularities in the model and 
are not the same concepts.

In the formulas, both are ok using 0.
I would suggest this (using p and q). IMHO, we will need to upload a -05 
asap.

    <Available Central Frequency Granularity> ::= (2^p) x 6.25GHz
      where p is a non negative integer, giving rise to granularities
      such as 6.25GHz, 12.5GHz, 25GHz, 50GHz, and 100GHz

    <Available Slot Width Granularity> ::= (2^q) x 12.5GHz
      where q is a non negative integer


In other words, I guess that the text before latest changes was ok, 
barred the unfortunate choice of names. But I would like to request for 
comments on this. Or maybe I am making things worse :)

R.


> /Jonas
>
> *From:*CCAMP [mailto:[e-mail]] *On Behalf Of *Ramon Casellas
> *Sent:* den 14 maj 2015 11:22
> *To:* [e-mail]
> *Subject:* Re: [CCAMP] WG Last Call on 
> draft-ietf-ccamp-flexi-grid-fwk-03 and call for sheperd
>
> Dear Matt, all
>
> Thank you very much for the review and comments, please see inline 
> (aligned with Adrian's reply).
>
> For what is worth, there were some comments that I received post LC, 
> that will also be in next updated version.
>
>
> El 12/05/2015 a las 0:02, Matt Hartley (mhartley) escribió:
>
>     All,
>
>     I’ve reviewed this revision of the document, and I think it’s
>     almost ready for publication. I have a few comments (below) but I
>     don’t think there’s any major issues.
>
>     3.1: definition of OTN could be moved up to section 2.2, if you want.
>
> Ramon> Added as acronym, and removed the expansion, thank you
>
> 3.2.1: you state that the Nominal Central Frequency Granularity is 
> 6.25GHz, but there’s no reference for this. I assume it’s in an ITU 
> doc somewhere? If so, it’d be good to say so (and where)
>
> Ramon> Indeed. Much like SWG being 12.5GHz, added [G.694.1]
>
> The document refers to “OTSi signals” in several places, but the 
> definition of “OTSi” includes “signal” :) I don’t know whether or not 
> this is normal usage or whether it’s worth fixing… but it looks 
> technically wrong to me (like people talking about “PIN numbers” 
> whenever they get cash out of the bank).
>
> Ramon> changed OTSi signals to OTSi
>
>
> 3.2.5, first bullet: “This group of OTSi should be carried over a 
> single fibre.” Is that a normal English should, or a 2219 SHOULD? If 
> the former, it might be worth rephrasing to avoid ambiguity.
>
> Ramon> changed to "are" as per Adrian's suggestion
>
> 4.2: “The association of the three components a filter, a fiber, and a 
> filter, is a media channel in its most basic form.”. It’d be nice to 
> clarify that this is a fiber with a filter at each end – that’s not 
> immediately obvious on first reading, especially with the diagram that 
> makes it clear on the next page.
>
> Ramon> Likewise, changed to "association sequence"
>
>
> The paragraph below figure 8 is... unclear. Is it just trying to say 
> that media channels can be joined together to make a new media 
> channel? Or is there more to it than that?
>
> Ramon> Basically the intent is that one, although it should reflect 
> more to the join of "basic" media channels (defined as an association 
> sequence of filter-fiber-filter as above). This, and the architectural 
> construct being an LSP.  Changed to also use the term "association 
> sequence"
>
> OLD
>
>     Additionally, when a cross-connect for a specific frequency slot is
>     considered, the underlying media support is still a media channel,
>     augmented, so to speak, with a bigger association of media elements
>     and a resulting effective slot.  When this media channel is the
>     result of the association of basic media channels and media layer
>     matrix cross-connects, this architectural construct can be
>     represented as (i.e., corresponds to) a Label Switched Path (LSP)
>     from a control plane perspective.  In other words, It is possible to
>     "concatenate" several media channels (e.g., Patch on intermediate
>     nodes) to create a single media channel.
>
>
> NEW
>
>     Additionally, when a cross-connect for a specific frequency slot is
>     considered, the resulting media support of joining basic media channels
>     is still a media channel, i.e., a longer association sequence of media
>     elements and its effective frequency slot. In other words, It is possible to
>     "concatenate" several media channels (e.g., patch on intermediate
>     nodes) to create a single media channel.
>   
>     The architectural construct resulting of the association sequence
>     of basic media channels and media layer matrix cross-connects can be
>     represented as (i.e., corresponds to) a Label Switched Path (LSP)
>     from a control plane perspective.
>
>
>
>
> Fig 12: OTSi trail? Did you mean OCh trail?
>
> Ramon> The error comes from the text, since the correct term is OTSi.
>
> OLD
>
>     In Figure 12 a Network Media Channel is represented as terminated at
>     the DWDM side of the transponder.  This is commonly named as OCh-
>     trail connection.
>   
>
> NEW
>
>     In Figure 12 a Network Media Channel is represented as terminated at
>     the network side of the transponders.  This is commonly named as OTSi-
>     trail connection.
>
>
>
> Fig 14: MLN/MRN needs explaining. Or removing.
>
> Ramon> Removed.
>
> 4.3, towards the end: “there must be enough guard band between 
> adjacent OTSis in any media channel to compensate filter concatenation 
> effect and other effects caused by signal layer switching elements”. 
> Maybe “…to compensate for the filter concatenation effect and…” or 
> “…to compensate for filter concatenation effects and…”?
>
> Ramon> new text
> "there must be  enough guard band between adjacent OTSis in any media 
> channel to  compensate for the filter concatenation effects and other 
> effects caused by signal layer switching elements"
>
>
> 4.8.4: bear in mind that 0 is not a positive integer, and it looks 
> like the definitions involving (2^n) and (2^m) are intended to include 
> the case where n/m is 0.
>
> Ramon> Changed for "n" to say "non-negative integer". For "m", I am 
> leaving it as positive integer, since m=0 would imply an empty 
> frequency slot.
>
>
> If no further comments, I will proceed to upload these changes for -04 
> (with other backlogged changes such as affiliation changes, CCAMP WG, 
> Informational, nits, editorial changes , typos, etc. ). Please see the 
> attached diff
>
>
> Thanks
> Ramon
>