Re: [Gen-art] Genart last call review of draft-ietf-pals-ethernet-cw-06

[Brian E Carpenter <[e-mail]>]

Hi Stewart,

On 02/07/2018 22:19, Stewart Bryant wrote:
> Hi Brian
> 
> Thank you for your review comments. Please see inline.
> 
> On 12/06/2018 04:30, Brian Carpenter wrote:
>> Reviewer: Brian Carpenter
>> Review result: Ready with Nits
>>
>> Gen-ART Last Call review of draft-ietf-pals-ethernet-cw-06
>>
>> I am the assigned Gen-ART reviewer for this draft. The General Area
>> Review Team (Gen-ART) reviews all IETF documents being processed
>> by the IESG for the IETF Chair.  Please treat these comments just
>> like any other last call comments.
>>
>> For more information, please see the FAQ at
>> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>>
>> Document: draft-ietf-pals-ethernet-cw-06.txt
>> Reviewer: Brian Carpenter
>> Review Date: 2018-06-12
>> IETF LC End Date: 2018-06-15
>> IESG Telechat date: 2018-06-21
>>
>> Summary: Ready with nits
>> --------
>>
>> Comments:
>> ---------
>>
>> This (with RFC4928) is a wonderful example of why layer violations are a Bad Thing.
>>
>> Nits:
>> -----
>>
>>> 1.  Introduction
>> ...
>>>    This document recommends the use of the Ethernet pseudowire control
>>>    word in all but exceptional circumstances.
>> That's wrong, it *mandates* this usage with a MUST (first paragraph of section 4).
> 
> The text with the MUST is
> 
> "This document updates {{RFC4448}} to state that
> where both the ingress PE and the egress PE support the Ethernet
> pseudowire control word, then the CW MUST be used."
> 
> This is conditional on both equipments supporting the feature.
> 
> During WG discussion there was a lot of discussion on the degree to
> which we would mandate the migration to CW.  The problem is that
> the use of the CW has hardware implications. At one stage we went
> so far as to recommend the the phasing out of equipment that could
> not support the CW, but we got strong pushback from a specialist part
> of the vendor community. This led us to a compromise position where
> we RECOMMEND the use of the CW, but only  mandate that the CW be
> used if it is available in the equipment used at both ends of
> the PW.

Fair enough, but the text doesn't quite say that.

OLD:
This document updates [RFC4448] to state that where both the
ingress PE and the egress PE support the Ethernet pseudowire control
word, then the CW MUST be used.

NEW:
This document updates [RFC4448] to state that both the
ingress PE and the egress PE SHOULD support the Ethernet
pseudowire control word, and that if supported the CW MUST be used.

Regards
    Brian

> 
>>> 3.  Background
>> ...
>>>    A recent posting on the Nanog email list has highlighted this
>>>    problem:
>>>
>>>    https://mailman.nanog.org/pipermail/nanog/2016-December/089395.html
>> No, it's no longer recent. How about:
>>
>>     For example, a posting on the N email list highlighted this
>>     problem:
> 
> I have changed the text to:
> 
> A posting on the NANOG email list highlighted this problem:
> 
> 
>>
>>> 7.  Operational Considerations
>>>
>>>    CW presence on the PW is controlled by the configuration and may be
>>>    subject to default operational mode of not being enabled.
>> That sentence is hard to parse. Try this:
>>
>>     A configuration switch might determine whether the CW is used on the PW.
>>     The default configuration might be to disable use of the CW.
> This now says:
> 
> In some cases, the inclusion of a CW in the PW is determined by
> equipment configuration. Furthermore, it is possible that the default
> configuration in such cases is  to disable use of the CW.
> 
> - Stewart
> 
>