Re: [mpls] Review of draft-ietf-mpls-residence-time-12

Greg Mirsky <gregimirsky@gmail.com> Thu, 19 January 2017 15:44 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Thu, 19 Jan 2017 07:44:13 -0800
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Subject: Re: [mpls] Review of draft-ietf-mpls-residence-time-12
To: "Acee Lindem (acee)" <acee@cisco.com>
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Hi Acee,
the draft defines optional functionality. If an operator has no use neither
for PTP's Transparent Clock, nor RTM itself as performance metric, then RTM
sub-TLV would not be included and thus it would not be flooded. Of course,
it be right to reflect RTM capability through YANG data model, thus
allowing SDN scenario you've described.

Regards,
Greg

On Wed, Jan 18, 2017 at 2:51 PM, Acee Lindem (acee) <acee@cisco.com> wrote:

> Hi Greg,
>
> Although it is a bit late, we’ve had some discussions amongst the IS-IS
> and OSPF chairs and are wondering whether the interface capability belongs
> in the IGPs. This will be flooded throughout the entire routing domain – is
> it really needed on every node or will it the RTM testing be initiated from
> an omniscient NMS client that would know the capabilities of each node or
> easily query them using YANG?
>
> Thanks,
> Acee
>
> From: mpls <mpls-bounces@ietf.org> on behalf of Greg Mirsky <
> gregimirsky@gmail.com>
> Date: Wednesday, January 18, 2017 at 1:25 PM
> To: Robert Sparks <rjsparks@nostrum.com>
> Cc: "mpls@ietf.org" <mpls@ietf.org>rg>, "gen-art@ietf.org" <gen-art@ietf.org>rg>,
> "draft-ietf-mpls-residence-time.all@ietf.org" <draft-ietf-mpls-residence-
> time.all@ietf.org>gt;, "ietf@ietf.org" <ietf@ietf.org>
> Subject: Re: [mpls] Review of draft-ietf-mpls-residence-time-12
>
> Hi Robert,
> thank you for the most expedient review and comments. I'll make changes in
> Section 2 per your suggestion.
>
> Regards,
> Greg
>
> On Wed, Jan 18, 2017 at 10:34 AM, Robert Sparks <rjsparks@nostrum.com>
> wrote:
>
>> The changes all look good.
>>
>> I still think you should say something in the document about what "the
>> time of packet arrival" and "transmission" means, and call out the point
>> you made about being careful to not introduce apparent jitter by not making
>> those measurements consistently. (The definitions you point to in your
>> earlier mail from G.8013 don't really help - they just say "time of packet
>> arrival". Again, the first and last bit are likely to be several
>> nanoseconds apart so I think it matters. Perhaps you're saying it doesn't
>> matter as long as each node is consistent (there will be error in the
>> residence time measurement, but it will be constant at each node, so the
>> sum of errors will be constant, and the clocks will be ok?)
>>
>> Please look at the new first paragraph of section 2 - there's a mix of
>> "as case" and "in case" that should be made consistent. I suspect it would
>> be easiest to simply say "referred to as using a one-step clock" and
>> "referred to as using a two-step clock" or similar.
>>
>> RjS
>>
>> On 1/18/17 12:03 PM, Greg Mirsky wrote:
>>
>> Hi Robert,
>> Sasha Vainshtein came with elegant idea to address disconnection between
>> discussion of one-step and two-step modes that you've pointed out. We've
>> moved Section 7 as sub-section into Section 2 now. Attached are updated
>> diff and the proposed new version -13.
>>
>> Regards,
>> Greg
>>
>> On Wed, Jan 18, 2017 at 8:13 AM, Greg Mirsky <gregimirsky@gmail.com>
>> wrote:
>>
>>> Hi Robert,
>>> once again, thank you for your thorough review and the most detailed
>>> comments. I've prepared updated version and would greatly appreciate if you
>>> review the changes and let us know whether your comments been addressed.
>>> Attached are diff and the new version.
>>>
>>> Regards,
>>> Greg
>>>
>>> On Wed, Jan 11, 2017 at 7:48 AM, Robert Sparks <rjsparks@nostrum.com>
>>> wrote:
>>>
>>>> Reviewer: Robert Sparks
>>>> Review result: Ready with Nits
>>>>
>>>> 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
>>>> <https://trac.ietf.org/trac/gen/wiki/GenArtfaq>.
>>>>
>>>> Document: draft-ietf-mpls-residence-time-12
>>>> Reviewer: Robert Sparks
>>>> Review Date: 2017-01-10
>>>> IETF LC End Date: 2017-01-17
>>>> IESG Telechat date: 2017-02-02
>>>>
>>>> Summary: Ready (with nits) for publication as a Proposed Standard
>>>>
>>>> I have two primary comments. I expect both are rooted in the authors
>>>> and working group knowing what the document means instead of seeing
>>>> what
>>>> it says or doesn't say:
>>>>
>>>> 1) The document is loose with its use of 'packet', and where TTLs
>>>> appear when
>>>> they are discussed. It might be helpful to rephrase the text that
>>>> speaks
>>>> of RTM packets in terms of RTM messages that are encoded as G-ACh
>>>> messages and
>>>> not refer to packets unless you mean the whole encapsulated packet
>>>> with MPLS
>>>> header, ACH, and G-ACh message.
>>>>
>>>> 2) Since this new mechanic speaks in terms of fractional nanoseconds,
>>>> some
>>>> discussion of what trigger-point you intend people to use for taking
>>>> the
>>>> precise time of a packet's arrival or departure seems warranted. (The
>>>> first and
>>>> last bit of the whole encapsulated packet above are going to appear at
>>>> the
>>>> physical layer many nanoseconds apart at OC192 speeds if I've done the
>>>> math
>>>> right). It may be obvious to the folks discussing this, but it's not
>>>> obvious
>>>> from the document.  If it's _not_ obvious and variation in technique
>>>> is
>>>> expected, then some discussion about issues that might arise from
>>>> different
>>>> implementation choices would be welcome.
>>>>
>>>> The rest of these are editorial nits:
>>>>
>>>> It would help to pull an overview description of the difference
>>>> between
>>>> one-step and two-step much earlier in the document. I suggest in the
>>>> overview
>>>> in section 2. Otherwise, the reader really has to jump forward and
>>>> read section
>>>> 7 before section 3's 5th bullet makes any sense.
>>>>
>>>> In section 3, "IANA will be asked" should be made active. Say "This
>>>> document
>>>> asks IANA to" and point to the IANA consideration section. Apply
>>>> similar
>>>> treatment to the other places where you talk about future IANA
>>>> actions.
>>>>
>>>> There are several places where there are missing words (typically
>>>> articles or
>>>> prepositions). You're less likely to end up with misinterpretations
>>>> during the
>>>> RFC Editor phase if you provide them before the document gets that far
>>>> in the
>>>> process. The spots I found most disruptive were these (this is not
>>>> intended to
>>>> be exhaustive):
>>>>
>>>>   Section 3: "set 1 according" -> "set to 1 according"
>>>>   Section 3: "the Table 19 [IEEE..." -> "Table 19 of [IEEE..."
>>>>   Section 4.2: "Detailed discussion of ... modes in Section 7."
>>>>                         -> "Detailed discussion of ... modes appears
>>>> in Section 7."
>>>>   Section 10: "most of" -> "most of all"
>>>>
>>>> In Setion 3.1 at "identity of the source port", please point into the
>>>> document
>>>> that defines this identity and its representation. I suspect this is a
>>>> pointer
>>>> into a specific section in IEEE.1588.2008].
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>