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

Stewart Bryant <stewart.bryant@gmail.com> Mon, 23 January 2017 09:30 UTC

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Subject: Re: [mpls] Review of draft-ietf-mpls-residence-time-12
To: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>, John E Drake <jdrake@juniper.net>, "Acee Lindem (acee)" <acee@cisco.com>, Alexander Vainshtein <Alexander.Vainshtein@ecitele.com>, Greg Mirsky <gregimirsky@gmail.com>
References: <148414970343.8167.4538946698521330202.idtracker@ietfa.amsl.com> <CA+RyBmVrvyiwDp2kV3VLiQtqOaL=MaVjZugGbvgWnp6y3dwP3Q@mail.gmail.com> <95d41b52-5c85-869f-2139-6713816e9637@nostrum.com> <CA+RyBmWcvU70BZYRj8ZHUZrmkcwq1eHS38jFpyZOq3A_5eXZ9g@mail.gmail.com> <D4A55AE0.9483E%acee@cisco.com> <CA+RyBmWrDhZUmVN0t8aLsL6F3ZfnvBu8FW_2VjDmwj-ercLd5w@mail.gmail.com> <f315026a140148898250f8fa3bdb0123@XCH-ALN-001.cisco.com> <CA+RyBmWMBAXd+zntuAeOU9x7xs9BQSk7J-z9+yyUDvKPd3v2MA@mail.gmail.com> <HE1PR0301MB22660A73C0D5A96BA8F3F0D39D7E0@HE1PR0301MB2266.eurprd03.prod.outlook.com> <D4A65103.94DF0%acee@cisco.com> <DM5PR05MB3001952D0DDD2AA672697094C77E0@DM5PR05MB3001.namprd05.prod.outlook.com> <D4A6573B.94E53%acee@cisco.com> <DM5PR05MB3001ED6AF8296F5DBE5E38EFC77E0@DM5PR05MB3001.namprd05.prod.outlook.com> <3f43cfdfe76e437bb2df6159e5644ae5@XCH-ALN-001.cisco.com> <DM5PR05MB30010B5F24F09914960A1192C77E0@DM5PR05MB3001.namprd05.prod.outlook.com> <a759def80742492ba46ff50d1405be9f@XCH-ALN-001.cisco.com>
From: Stewart Bryant <stewart.bryant@gmail.com>
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Date: Mon, 23 Jan 2017 09:29:55 +0000
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Cc: "Abhay Roy \(akr\)" <akr@cisco.com>, "mpls@ietf.org" <mpls@ietf.org>, "isis-chairs@ietf.org" <isis-chairs@ietf.org>, "gen-art@ietf.org" <gen-art@ietf.org>, "draft-ietf-mpls-residence-time.all@ietf.org" <draft-ietf-mpls-residence-time.all@ietf.org>, "ietf@ietf.org" <ietf@ietf.org>
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Les

This is very much path related and thus it is entirely reasonable to 
carry it in the IGP.

If you want a path that gives you the highest quality time transfer, 
then you need to select a path on which every hop provides the 
information needed to minimise the uncertainly in the transit delay 
time. Thus I can see paths being chosen on the basis that every hop 
performs this service. That is obviously a routing decision and thus it 
is reasonable to advertise the information needed to make that decision 
in the routing protocol.

- Stewart


On 19/01/2017 21:08, Les Ginsberg (ginsberg) wrote:
>
> John –
>
> The text you have excerpted below was trying to say two things:
>
> 1)If you want to advertise this in the IGPs the OSPF style proposal is 
> much better from an implementation standpoint than the IS-IS GENAPP 
> proposal
>
> 2)There is a larger question as to whether we should be using the IGPs 
> for this at all
>
> Statement #1 should not be interpreted to imply that I am advocating 
> using the IGPs. J
>
> That said, we “ALWAYS” end up choosing using the IGPs to do this sort 
> of thing – not because it is the “RIGHT” thing to do architecturally – 
> but because it is so convenient.
>
> I am just asking for folks to pause and think about this a bit more 
> from an architectural perspective.
>
> Les
>
> *From:*John E Drake [mailto:jdrake@juniper.net]
> *Sent:* Thursday, January 19, 2017 12:20 PM
> *To:* Les Ginsberg (ginsberg); Acee Lindem (acee); Alexander 
> Vainshtein; Greg Mirsky
> *Cc:* Robert Sparks; mpls@ietf.org; gen-art@ietf.org; 
> draft-ietf-mpls-residence-time.all@ietf.org; ietf@ietf.org; 
> isis-chairs@ietf.org; Abhay Roy (akr)
> *Subject:* RE: [mpls] Review of draft-ietf-mpls-residence-time-12
>
> Les,
>
> Comments inline.
>
> Yours Irrespectively,
>
> John
>
> *From:*Les Ginsberg (ginsberg) [mailto:ginsberg@cisco.com]
> *Sent:* Thursday, January 19, 2017 12:25 PM
> *To:* John E Drake <jdrake@juniper.net <mailto:jdrake@juniper.net>>; 
> Acee Lindem (acee) <acee@cisco.com <mailto:acee@cisco.com>>; Alexander 
> Vainshtein <Alexander.Vainshtein@ecitele.com 
> <mailto:Alexander.Vainshtein@ecitele.com>>; Greg Mirsky 
> <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>
> *Cc:* Robert Sparks <rjsparks@nostrum.com 
> <mailto:rjsparks@nostrum.com>>; mpls@ietf.org <mailto:mpls@ietf.org>; 
> gen-art@ietf.org <mailto:gen-art@ietf.org>; 
> draft-ietf-mpls-residence-time.all@ietf.org 
> <mailto:draft-ietf-mpls-residence-time.all@ietf.org>; ietf@ietf.org 
> <mailto:ietf@ietf.org>; isis-chairs@ietf.org 
> <mailto:isis-chairs@ietf.org>; Abhay Roy (akr) <akr@cisco.com 
> <mailto:akr@cisco.com>>
> *Subject:* RE: [mpls] Review of draft-ietf-mpls-residence-time-12
>
> John –
>
> For me, this raises the age-old question of when it is/is not 
> appropriate to use IGPs for flooding information.
>
> This is clearly not TE information – you just happen to be using this 
> in conjunction with MPLS – but it is a generic capability. I do not 
> see the IGPs as the appropriate mechanism to flood generic interface 
> capabilities. It also, as Acee has pointed out, results in flooding 
> information to all nodes in the domain when only a few care about it.
>
> *//*
>
> */[JD] RTM support as defined in the draft would be used to provide 
> extremely accurate time synchronization in an MPLS network so I would 
> suggest that all nodes in such a network would be using it and hence 
> that it does belong in the IGP.  As an aside, advertising it in the 
> IGP facilitates incremental or partial deployment.  Your yesterday’s 
> email supports this: /*
>
> *//*
>
> */“It would seem more appropriate to treat RTM information either as:/*
>
> *//*
>
> */o an extension to link attribute information already advertised by 
> the IGPs (as has been suggested for OSPF) - which would suggest in 
> IS-IS a sub-TLV of TLV 22(et al)/*
>
> *//*
>
> */or/*
>
> *//*
>
> ·*/As an interface attribute independent of routing protocols which 
> could be retrieved utilizing network management tools”/*
>
> Les
>
> *From:*John E Drake [mailto:jdrake@juniper.net]
> *Sent:* Thursday, January 19, 2017 8:54 AM
> *To:* Acee Lindem (acee); Alexander Vainshtein; Greg Mirsky; Les 
> Ginsberg (ginsberg)
> *Cc:* Robert Sparks; mpls@ietf.org <mailto:mpls@ietf.org>; 
> gen-art@ietf.org <mailto:gen-art@ietf.org>; 
> draft-ietf-mpls-residence-time.all@ietf.org 
> <mailto:draft-ietf-mpls-residence-time.all@ietf.org>; ietf@ietf.org 
> <mailto:ietf@ietf.org>; isis-chairs@ietf.org 
> <mailto:isis-chairs@ietf.org>; Abhay Roy (akr)
> *Subject:* RE: [mpls] Review of draft-ietf-mpls-residence-time-12
>
> Acee,
>
> Relying on an omniscient controller is a non-starter in general and in 
> particular because the protocol by which it would learn each node’s 
> RTM capabilities and distribute them to the other nodes is undefined. 
> Further, one of the ways by which an omniscient controller learns a 
> node’s capabilities is by snooping the link/state database.
>
> Yours Irrespectively,
>
> John
>
> *From:*Acee Lindem (acee) [mailto:acee@cisco.com]
> *Sent:* Thursday, January 19, 2017 11:47 AM
> *To:* John E Drake <jdrake@juniper.net <mailto:jdrake@juniper.net>>; 
> Alexander Vainshtein <Alexander.Vainshtein@ecitele.com 
> <mailto:Alexander.Vainshtein@ecitele.com>>; Greg Mirsky 
> <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>; Les Ginsberg 
> (ginsberg) <ginsberg@cisco.com <mailto:ginsberg@cisco.com>>
> *Cc:* Robert Sparks <rjsparks@nostrum.com 
> <mailto:rjsparks@nostrum.com>>; mpls@ietf.org <mailto:mpls@ietf.org>; 
> gen-art@ietf.org <mailto:gen-art@ietf.org>; 
> draft-ietf-mpls-residence-time.all@ietf.org 
> <mailto:draft-ietf-mpls-residence-time.all@ietf.org>; ietf@ietf.org 
> <mailto:ietf@ietf.org>; isis-chairs@ietf.org 
> <mailto:isis-chairs@ietf.org>; Abhay Roy (akr) <akr@cisco.com 
> <mailto:akr@cisco.com>>
> *Subject:* Re: [mpls] Review of draft-ietf-mpls-residence-time-12
>
> Hi John,
>
> *From: *John E Drake <jdrake@juniper.net <mailto:jdrake@juniper.net>>
> *Date: *Thursday, January 19, 2017 at 10:43 AM
> *To: *Acee Lindem <acee@cisco.com <mailto:acee@cisco.com>>, Alexander 
> Vainshtein <Alexander.Vainshtein@ecitele.com 
> <mailto:Alexander.Vainshtein@ecitele.com>>, Greg Mirsky 
> <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>, "Les Ginsberg 
> (ginsberg)" <ginsberg@cisco.com <mailto:ginsberg@cisco.com>>
> *Cc: *Robert Sparks <rjsparks@nostrum.com 
> <mailto:rjsparks@nostrum.com>>, "mpls@ietf.org <mailto:mpls@ietf.org>" 
> <mpls@ietf.org <mailto:mpls@ietf.org>>, "gen-art@ietf.org 
> <mailto:gen-art@ietf.org>" <gen-art@ietf.org 
> <mailto:gen-art@ietf.org>>, 
> "draft-ietf-mpls-residence-time.all@ietf.org 
> <mailto:draft-ietf-mpls-residence-time.all@ietf.org>" 
> <draft-ietf-mpls-residence-time.all@ietf.org 
> <mailto:draft-ietf-mpls-residence-time.all@ietf.org>>, "ietf@ietf.org 
> <mailto:ietf@ietf.org>" <ietf@ietf.org <mailto:ietf@ietf.org>>, 
> "isis-chairs@ietf.org <mailto:isis-chairs@ietf.org>" 
> <isis-chairs@ietf.org <mailto:isis-chairs@ietf.org>>, "Abhay Roy 
> (akr)" <akr@cisco.com <mailto:akr@cisco.com>>
> *Subject: *RE: [mpls] Review of draft-ietf-mpls-residence-time-12
>
>     Acee,
>
>     We discussed all of this with you over a year ago and used your
>     guidance in adding the indication of RTM capability to OSPF.
>
> I’m sorry but I focused mainly on the OSPF protocol aspects then and 
> didn’t question the use case. This question came up in the IS-IS WG 
> discussions.
>
> Thanks,
>
> Acee
>
>     Yours Irrespectively,
>
>     John
>
>     *From:*Acee Lindem (acee) [mailto:acee@cisco.com]
>     *Sent:* Thursday, January 19, 2017 11:38 AM
>     *To:* Alexander Vainshtein <Alexander.Vainshtein@ecitele.com
>     <mailto:Alexander.Vainshtein@ecitele.com>>; Greg Mirsky
>     <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>; Les
>     Ginsberg (ginsberg) <ginsberg@cisco.com <mailto:ginsberg@cisco.com>>
>     *Cc:* Robert Sparks <rjsparks@nostrum.com
>     <mailto:rjsparks@nostrum.com>>; mpls@ietf.org
>     <mailto:mpls@ietf.org>; gen-art@ietf.org
>     <mailto:gen-art@ietf.org>;
>     draft-ietf-mpls-residence-time.all@ietf.org
>     <mailto:draft-ietf-mpls-residence-time.all@ietf.org>;
>     ietf@ietf.org <mailto:ietf@ietf.org>; isis-chairs@ietf.org
>     <mailto:isis-chairs@ietf.org>; Abhay Roy (akr) <akr@cisco.com
>     <mailto:akr@cisco.com>>
>     *Subject:* Re: [mpls] Review of draft-ietf-mpls-residence-time-12
>
>     I guess what we were trying to envision the use case and whether
>     it makes sense for all the nodes in the IGP routing domain to have
>     this information. Would the LSP ingress LSR only need to if the
>     egress LSR supports RTM and it is best effort recording for
>     transit LSRs in the path?
>
>     Additionally, if it is needed in the IGPs, should there also be a
>     BGP-LS Link Attribute TLV proposed?
>
>     Thanks,
>
>     Acee
>
>     *From: *Alexander Vainshtein <Alexander.Vainshtein@ecitele.com
>     <mailto:Alexander.Vainshtein@ecitele.com>>
>     *Date: *Thursday, January 19, 2017 at 10:15 AM
>     *To: *Greg Mirsky <gregimirsky@gmail.com
>     <mailto:gregimirsky@gmail.com>>, "Les Ginsberg (ginsberg)"
>     <ginsberg@cisco.com <mailto:ginsberg@cisco.com>>
>     *Cc: *Acee Lindem <acee@cisco.com <mailto:acee@cisco.com>>, Robert
>     Sparks <rjsparks@nostrum.com <mailto:rjsparks@nostrum.com>>,
>     "mpls@ietf.org <mailto:mpls@ietf.org>" <mpls@ietf.org
>     <mailto:mpls@ietf.org>>, "gen-art@ietf.org
>     <mailto:gen-art@ietf.org>" <gen-art@ietf.org
>     <mailto:gen-art@ietf.org>>,
>     "draft-ietf-mpls-residence-time.all@ietf.org
>     <mailto:draft-ietf-mpls-residence-time.all@ietf.org>"
>     <draft-ietf-mpls-residence-time.all@ietf.org
>     <mailto:draft-ietf-mpls-residence-time.all@ietf.org>>,
>     "ietf@ietf.org <mailto:ietf@ietf.org>" <ietf@ietf.org
>     <mailto:ietf@ietf.org>>, "isis-chairs@ietf.org
>     <mailto:isis-chairs@ietf.org>" <isis-chairs@ietf.org
>     <mailto:isis-chairs@ietf.org>>, "Abhay Roy (akr)" <akr@cisco.com
>     <mailto:akr@cisco.com>>
>     *Subject: *RE: [mpls] Review of draft-ietf-mpls-residence-time-12
>
>         Hi all,
>
>         I concur with Greg: from my POV an interoperable solution
>         should not depend on an omniscient NMS client distributing
>         information about capabilities of each node to each other node.
>
>         Regards,
>
>         Sasha
>
>         Office: +972-39266302
>
>         Cell: +972-549266302
>
>         Email: Alexander.Vainshtein@ecitele.com
>         <mailto:Alexander.Vainshtein@ecitele.com>
>
>         *From:*Greg Mirsky [mailto:gregimirsky@gmail.com]
>         *Sent:* Thursday, January 19, 2017 6:01 PM
>         *To:* Les Ginsberg (ginsberg) <ginsberg@cisco.com
>         <mailto:ginsberg@cisco.com>>
>         *Cc:* Acee Lindem (acee) <acee@cisco.com
>         <mailto:acee@cisco.com>>; Robert Sparks <rjsparks@nostrum.com
>         <mailto:rjsparks@nostrum.com>>; mpls@ietf.org
>         <mailto:mpls@ietf.org>; gen-art@ietf.org
>         <mailto:gen-art@ietf.org>;
>         draft-ietf-mpls-residence-time.all@ietf.org
>         <mailto:draft-ietf-mpls-residence-time.all@ietf.org>;
>         ietf@ietf.org <mailto:ietf@ietf.org>; isis-chairs@ietf.org
>         <mailto:isis-chairs@ietf.org>; Abhay Roy (akr) <akr@cisco.com
>         <mailto:akr@cisco.com>>
>         *Subject:* Re: [mpls] Review of draft-ietf-mpls-residence-time-12
>
>         Hi Les,
>
>         I believe that IGP extensions to advertise RTM capability are
>         required.
>
>         Regards,
>
>         Greg
>
>         On Thu, Jan 19, 2017 at 7:57 AM, Les Ginsberg (ginsberg)
>         <ginsberg@cisco.com <mailto:ginsberg@cisco.com>> wrote:
>
>             Greg –
>
>             I am having trouble understanding your response.
>
>             The question we are raising is whether we should extend
>             the IGPs to support advertising RTM capability – an
>             alternative being to retrieve the capability via network
>             management.
>
>             Saying that the IGP functionality is optional and/or
>             wouldn’t always be advertised doesn’t really answer the
>             question of whether we should or should not define the IGP
>             extensions.
>
>             Could you respond more directly to this point?
>
>             Les
>
>             *From:*Greg Mirsky [mailto:gregimirsky@gmail.com
>             <mailto:gregimirsky@gmail.com>]
>             *Sent:* Thursday, January 19, 2017 7:44 AM
>             *To:* Acee Lindem (acee)
>             *Cc:* Robert Sparks; mpls@ietf.org <mailto:mpls@ietf.org>;
>             gen-art@ietf.org <mailto:gen-art@ietf.org>;
>             draft-ietf-mpls-residence-time.all@ietf.org
>             <mailto:draft-ietf-mpls-residence-time.all@ietf.org>;
>             ietf@ietf.org <mailto:ietf@ietf.org>; Les Ginsberg
>             (ginsberg); isis-chairs@ietf.org
>             <mailto:isis-chairs@ietf.org>; Abhay Roy (akr)
>
>
>             *Subject:* Re: [mpls] Review of
>             draft-ietf-mpls-residence-time-12
>
>             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 <mailto: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
>             <mailto:mpls-bounces@ietf.org>> on behalf of Greg Mirsky
>             <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>
>             *Date: *Wednesday, January 18, 2017 at 1:25 PM
>             *To: *Robert Sparks <rjsparks@nostrum.com
>             <mailto:rjsparks@nostrum.com>>
>             *Cc: *"mpls@ietf.org <mailto:mpls@ietf.org>"
>             <mpls@ietf.org <mailto:mpls@ietf.org>>, "gen-art@ietf.org
>             <mailto:gen-art@ietf.org>" <gen-art@ietf.org
>             <mailto:gen-art@ietf.org>>,
>             "draft-ietf-mpls-residence-time.all@ietf.org
>             <mailto:draft-ietf-mpls-residence-time.all@ietf.org>"
>             <draft-ietf-mpls-residence-time.all@ietf.org
>             <mailto:draft-ietf-mpls-residence-time.all@ietf.org>>,
>             "ietf@ietf.org <mailto:ietf@ietf.org>" <ietf@ietf.org
>             <mailto: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 <mailto: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
>                     <mailto: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
>                     <mailto: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].
>