Re: [CCAMP] I-D Action: draft-lee-ccamp-wson-impairment-yang-00.txt

[Dieter Beller <[e-mail]>]

Hi Young and Haomian,

I had a look at draft-lee-ccamp-wson-impairment-yang-00, which you submitted a few weeks ago and I have the following concerns:

The abstract and introduction states:

Abstract

   This document provides a YANG data model for the impairment-aware TE
   topology in wavelength switched optical networks (WSONs).

1. Introduction

   ...

   This document provides a YANG data model for the impairment-aware
   Traffic Engineering (TE) topology in wavelength switched optical
   networks (WSONs). The YANG model described in this document is a
   WSON technology-specific Yang model based on the information model
   developed in [https://tools.ietf.org/html/rfc7446" title='"Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks"' rel="nofollow">RFC7446] and the two encoding documents [https://tools.ietf.org/html/rfc7581" title='"Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks"' rel="nofollow">RFC7581] and
   [https://tools.ietf.org/html/rfc7579" title='"General Network Element Constraint Encoding for GMPLS Controlled Networks"' rel="nofollow">RFC7579] that developed protocol independent encodings based on
   [https://tools.ietf.org/html/rfc7446" title='"Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks"' rel="nofollow">RFC7446].

Based on this scope, I was expecting that this I-D provides te-link augmentations for WSON networks.
Examples of WSON specific te-link attributes are fiber type, spectrum availability, chromatic dispersion, PMD, PDL, OSNR contribution (if the link includes ILAs) just to list a few.

However, the only te-link augmentation is:

     augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-attributes:
       +--ro power?   int32

It is also reasonable to define WSON augmentations for termination points representing the line side of optical transponders as they can be considered as topological elements
even if these attributes are not representing optical impairments!:

     augment /nw:networks/nw:network/nw:node/tet:te/tet:tunnel-termination-point:
       +--ro available-modulation*   identityref
       +--ro modulation-enabled?     boolean
       +--ro modulation-type?        identityref
       +--ro available-FEC*          identityref
       +--ro FEC-enabled?            boolean
       +--ro FEC-type?               identityref
       +--ro FEC-code-rate?          decimal64
       +--ro FEC-threshold?          decimal64

I don't understand why all the OT attributes are defined as ro attributes. State of the art OTs typically provide multiple operational modes. Hence, these attributes should
be defined as rw attributes.

 
All other augmentations are defined for paths (te-tunnels) or termination points, which is a bit strange! Here are two examples:

     augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-
   attributes/tet:underlay/tet:primary-path/tet:path-
   element/tet:type/tet:label/tet:label-hop/tet:te-label/tet:technology:
       +--:(wson-imp-topo)
          +--rw (grid-type)?
          |  +--:(dwdm)
          |  |  +--ro channel-freq?         decimal64
          |  +--:(cwdm)
          |     +--ro channel-wavelength?   uint32
          +--ro bit-rate?             decimal64
          +--ro BER?                  decimal64
          +--ro pmd?                  decimal64
          +--ro cd?                   decimal64
          +--ro osnr?                 decimal64
          +--ro q-factor?             decimal64

channel-freq/channel-wavelength, bit-rate, BER are definitively service (te-tunnel) attributes and do not represent optical impairments for a WSON network topology.
For pmd, cd, and q-factor (definition?), it looks like these are attributes for all the links along the path. Why are these impairments defined for a path and are not te-link
augmentations?

I was expecting that this draft defines optical impairments for the topological entities in a WSON network where optical impairments matter. Could you please clarify.


Thanks,
Dieter


On 01.09.2018 05:42, [e-mail] wrote:

A New Internet-Draft is available from the on-line Internet-Drafts directories.


        Title           : A Yang Data Model for Impairment-Aware WSON Optical Networks
        Authors         : Young Lee
                          Haomian Zheng
	Filename        : draft-lee-ccamp-wson-impairment-yang-00.txt
	Pages           : 18
	Date            : 2018-08-31

Abstract:
   This document provides a YANG data model for the impairment-aware TE
   topology in wavelength switched optical networks (WSONs).




The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-lee-ccamp-wson-impairment-yang/" rel="nofollow">https://datatracker.ietf.org/doc/draft-lee-ccamp-wson-impairment-yang/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-lee-ccamp-wson-impairment-yang-00" rel="nofollow">https://tools.ietf.org/html/draft-lee-ccamp-wson-impairment-yang-00
https://datatracker.ietf.org/doc/html/draft-lee-ccamp-wson-impairment-yang-00" rel="nofollow">https://datatracker.ietf.org/doc/html/draft-lee-ccamp-wson-impairment-yang-00


Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/" rel="nofollow">ftp://ftp.ietf.org/internet-drafts/

_______________________________________________
I-D-Announce mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/i-d-announce" rel="nofollow">https://www.ietf.org/mailman/listinfo/i-d-announce
Internet-Draft directories: http://www.ietf.org/shadow.html" rel="nofollow">http://www.ietf.org/shadow.html
or ftp://ftp.ietf.org/ietf/1shadow-sites.txt" rel="nofollow">ftp://ftp.ietf.org/ietf/1shadow-sites.txt