Re: [CCAMP] [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt

[Tomonori Takeda <[e-mail]>]

Hi Young,

Thanks.

Two follow-up questions/comments.
(I am fine with other points, which you already addressed in the updated draft.)

> 2) In section 2.1, it says "two matrices will not have the same {src port, src label, dst port, dst label}". To be precise, I guess this should be > "two matrices will not have the same {src port, src label}, and two matrices will not have the same {dst port, dst label}"?
> 
> YOUNG>> I think your suggestion may be too restrictive. For instance, if we have one source (port 1) and one destination (port 2) with two labels > each. Then we would have: {(1,1,2,1), (1,1,2,2), (1,2,2,1), (1,2,2,2)} I think with the current statement, we can send this info in any combination > of multiple matrices, which I think perfectly fine. With your suggestion, I would not be able send (1,1,2,1) and (1,1,2,2) together. Why would this > not be made possible? My take is as long as each submatrix represents a set of disjoint quadruples, that should be allowed.

My reading of "two matrices will not have the same {src port, src label, dst port, dst label}" is as follows.

<Example A>

  input port=1  --> Submatrix#1 --> output port=2
  input label=1                     output label=1

  input port=1  --> Submatrix#2 --> output port=2
  input label=1                     output label=2

  This is allowed.

<Example B>

  input port=1  --> Submatrix#1 --> output port=2
  input label=1                     output label=1

  input port=1  --> Submatrix#2 --> output port=2
  input label=1                     output label=1

  This is not allowed.

<Example C>

  input port=1  --> Submatrix#1 --> output port=2
  input label=1                     output label=1

  input port=1  --> Submatrix#2 --> output port=2
  input label=2                     output label=2

  This is allowed.

Is above understanding correct?
If so, I am not sure how example A works, since I am not sure what is the indentifier to direct from input to each submatrix.

Maybe I am mis-understanding what sub-matrix is. I thought sub-matrix is a sort of virtual node, splitting the single matrix (or switch) into smaller pieces.

> 4) In section 2.1, for Link Set A dir=bidirectional, Link Set B dir=bidirectional, if any signal on an input link X is output on a link Y, then any > signal on an input link Y is output on a link X (after cross-connect)? Or any constraint on such signal flow (after cross-connect) is out of scope?
> 
> <YOUNG>> I am not sure what "after cross-connect" is meant.

<Example>

  Link set A: link#1, link#2, link#3
  Link set B: link#4, link#5, link#6

  Both of Link set A and Link set B are specified as "dir".

  In this case,
  - Is it possible to problem the cross-connect as input=link#1, output=link#4
    & input=link#5, output=link#1 simultaneolusly?
  - Or is it automatically assumed if input=link#1, output=link#4,
    then input=link#4, output=link#1?
  - Or this sort of constraint is not specified in Link Set Field?

The text seems like saying the first option, but I do not think this is a common equipment implementaion.

Thanks,
Tomonori

-----Original Message-----
From: Leeyoung [mailto:[e-mail]] 
Sent: Tuesday, January 20, 2015 7:54 AM
To: Tomonori Takeda（武田知典）; [e-mail]
Cc: '[e-mail]'; '[e-mail]'; '[e-mail]'
Subject: RE: [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt

Hi Tomonori,

Thanks for providing good comments. Here's my response. Please see in-line.

Regards,
Young

-----Original Message-----
From: rtg-dir [mailto:[e-mail]] On Behalf Of Tomonori Takeda
Sent: Saturday, January 17, 2015 7:59 AM
To: [e-mail]
Cc: '[e-mail]'; '[e-mail]'; '[e-mail]'
Subject: [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt

Hello, 

I have been selected as the Routing Directorate reviewer for this draft. The Routing Directorate seeks to review all routing or routing-related drafts as they pass through IETF last call and IESG review, and sometimes on special request. The purpose of the review is to provide assistance to the Routing ADs. For more information about the Routing Directorate, please see ​http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir 

Although these comments are primarily for the use of the Routing ADs, it would be helpful if you could consider them along with any other IETF Last Call comments that you receive, and strive to resolve them through discussion or by updating the draft. 

Document: draft-ietf-ccamp-general-constraint-encode-16.txt 
Reviewer: Tomonori Takeda
Review Date: 17 January, 2015
IETF LC End Date: 17 January, 2015
Intended Status: Standards Track

Summary:

This document is basically ready for publication, but has nits that should be considered prior to publication.

Comments:

This document specifies protocol-agnostic encodings for general information elements described in draft-ietf-ccamp-rwa-info.
I think the document is in good shape but there are a few points that should be clarified for better understanding.

Major Issues:

None

Minor Issues:

None

Nits:

1) In section 1.2, label continuity constraint (e.g., wavelength continuity in WSON) is mentioned. However, I am not sure whether information elements for which this document specifies encodings can describe such constraint. My reading is that information element such as Port Label Restriction is rather for describing wavelength tuning capabilities/restrictions.

YOUNG>> Label continuity constraints can be inferred from the two places in the draft: (i) Port Label Restriction, which gives the set of labels (wavelengths) that may not be available on certain links including tuning range/restriction; (ii) Available/Shared Backup Label Fields (section 2.4 & section 2.5). There is no encoding for label continuity constraint per se. The aforementioned constraints are encoded to give a node or a PCE to be able to compute a path (i.e., path with wavelength continuity) subject to these constraints. 

2) In section 2.1, it says "two matrices will not have the same {src port, src label, dst port, dst label}". To be precise, I guess this should be "two matrices will not have the same {src port, src label}, and two matrices will not have the same {dst port, dst label}"?

YOUNG>> I think your suggestion may be too restrictive. For instance, if we have one source (port 1) and one destination (port 2) with two labels each. Then we would have: {(1,1,2,1), (1,1,2,2), (1,2,2,1), (1,2,2,2)} I think with the current statement, we can send this info in any combination of multiple matrices, which I think perfectly fine. With your suggestion, I would not be able send (1,1,2,1) and (1,1,2,2) together. Why would this not be made possible? My take is as long as each submatrix represents a set of disjoint quadruples, that should be allowed. 

3) In section 2.1, it says "The value of 0xFF is reserved for use with port wavelength constraints". I think "port wavelength constraints" should be "port label restriction".

YOUNG>> Yes, thanks. 

4) In section 2.1, for Link Set A dir=bidirectional, Link Set B dir=bidirectional, if any signal on an input link X is output on a link Y, then any signal on an input link Y is output on a link X (after cross-connect)? Or any constraint on such signal flow (after cross-connect) is out of scope?

YOUNG>> I am not sure what "after cross-connect" is meant. 

5) In section 2.2.1, it says "In this case the accompanying label set indicates the labels permitted on the port." I think "port" should be "port/matrix".

YOUNG>> Yes, thanks. 

6) In section 2.2.2, it would be better to describe the type (e.g., integer) for MaxNumChannels.
This also applies for MaxLabelRange (in section 2.2.3) and Num Labels (in section 2.6).

YOUNG>> OK. 

7) In section 2.6, it says "Label Set Field is used within the <AvailableLabels> or the <SharedBackupLabels>". But I think Label Set Field is also used within SIMPLE_LABEL, LABEL_RANGE and SIMPLE_LABEL & CHANNEL_COUNT.

YOUNG>> Yes, it is used in multiple places. 

How about:
OLD: Label Set Field is used within the <AvailableLabels> or the
   <SharedBackupLabels>, which is defined in Section 2.4. and 2.5.,
   respectively.
NEW: Label Set Field is used within the <AvailableLabels> or the
   <SharedBackupLabels>, which is defined in Section 2.4. and 2.5.,
   respectively. It is also used within the <SIMPLE_LABEL>, 
   <LABEL_RANGE>, <SIMPLE_LABEL> or <CHANNEL_COUNT>, which is defined
   in Sections 2.1.1 - 2.1.4, respectively. 


Thanks,
Tomonori