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

2017-01-23 12:51:30

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(_at_)juniper(_dot_)net]
*Sent:* Thursday, January 19, 2017 12:20 PM
*To:* Les Ginsberg (ginsberg); Acee Lindem (acee); Alexander Vainshtein; Greg Mirsky *Cc:* Robert Sparks; mpls(_at_)ietf(_dot_)org; gen-art(_at_)ietf(_dot_)org; draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org; isis-chairs(_at_)ietf(_dot_)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(_at_)cisco(_dot_)com]
*Sent:* Thursday, January 19, 2017 12:25 PM
*To:* John E Drake <jdrake(_at_)juniper(_dot_)net <mailto:jdrake(_at_)juniper(_dot_)net>>; Acee Lindem (acee) <acee(_at_)cisco(_dot_)com <mailto:acee(_at_)cisco(_dot_)com>>; Alexander Vainshtein <Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com <mailto:Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com>>; Greg Mirsky <gregimirsky(_at_)gmail(_dot_)com <mailto:gregimirsky(_at_)gmail(_dot_)com>> *Cc:* Robert Sparks <rjsparks(_at_)nostrum(_dot_)com <mailto:rjsparks(_at_)nostrum(_dot_)com>>; mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>; gen-art(_at_)ietf(_dot_)org <mailto:gen-art(_at_)ietf(_dot_)org>; draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>; isis-chairs(_at_)ietf(_dot_)org <mailto:isis-chairs(_at_)ietf(_dot_)org>; Abhay Roy (akr) <akr(_at_)cisco(_dot_)com <mailto:akr(_at_)cisco(_dot_)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(_at_)juniper(_dot_)net]
*Sent:* Thursday, January 19, 2017 8:54 AM
*To:* Acee Lindem (acee); Alexander Vainshtein; Greg Mirsky; Les Ginsberg (ginsberg) *Cc:* Robert Sparks; mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>; gen-art(_at_)ietf(_dot_)org <mailto:gen-art(_at_)ietf(_dot_)org>; draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>; isis-chairs(_at_)ietf(_dot_)org <mailto:isis-chairs(_at_)ietf(_dot_)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(_at_)cisco(_dot_)com]
*Sent:* Thursday, January 19, 2017 11:47 AM
*To:* John E Drake <jdrake(_at_)juniper(_dot_)net <mailto:jdrake(_at_)juniper(_dot_)net>>; Alexander Vainshtein <Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com <mailto:Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com>>; Greg Mirsky <gregimirsky(_at_)gmail(_dot_)com <mailto:gregimirsky(_at_)gmail(_dot_)com>>; Les Ginsberg (ginsberg) <ginsberg(_at_)cisco(_dot_)com <mailto:ginsberg(_at_)cisco(_dot_)com>> *Cc:* Robert Sparks <rjsparks(_at_)nostrum(_dot_)com <mailto:rjsparks(_at_)nostrum(_dot_)com>>; mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>; gen-art(_at_)ietf(_dot_)org <mailto:gen-art(_at_)ietf(_dot_)org>; draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>; isis-chairs(_at_)ietf(_dot_)org <mailto:isis-chairs(_at_)ietf(_dot_)org>; Abhay Roy (akr) <akr(_at_)cisco(_dot_)com <mailto:akr(_at_)cisco(_dot_)com>>
*Subject:* Re: [mpls] Review of draft-ietf-mpls-residence-time-12

Hi John,

*From: *John E Drake <jdrake(_at_)juniper(_dot_)net 
<mailto:jdrake(_at_)juniper(_dot_)net>>
*Date: *Thursday, January 19, 2017 at 10:43 AM
*To: *Acee Lindem <acee(_at_)cisco(_dot_)com <mailto:acee(_at_)cisco(_dot_)com>>, Alexander Vainshtein <Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com <mailto:Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com>>, Greg Mirsky <gregimirsky(_at_)gmail(_dot_)com <mailto:gregimirsky(_at_)gmail(_dot_)com>>, "Les Ginsberg (ginsberg)" <ginsberg(_at_)cisco(_dot_)com <mailto:ginsberg(_at_)cisco(_dot_)com>> *Cc: *Robert Sparks <rjsparks(_at_)nostrum(_dot_)com <mailto:rjsparks(_at_)nostrum(_dot_)com>>, "mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>" <mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>>, "gen-art(_at_)ietf(_dot_)org <mailto:gen-art(_at_)ietf(_dot_)org>" <gen-art(_at_)ietf(_dot_)org <mailto:gen-art(_at_)ietf(_dot_)org>>, "draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>" <draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>>, "ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>" <ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>>, "isis-chairs(_at_)ietf(_dot_)org <mailto:isis-chairs(_at_)ietf(_dot_)org>" <isis-chairs(_at_)ietf(_dot_)org <mailto:isis-chairs(_at_)ietf(_dot_)org>>, "Abhay Roy (akr)" <akr(_at_)cisco(_dot_)com <mailto:akr(_at_)cisco(_dot_)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(_at_)cisco(_dot_)com]
    *Sent:* Thursday, January 19, 2017 11:38 AM
    *To:* Alexander Vainshtein 
<Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com
    <mailto:Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com>>; Greg Mirsky
    <gregimirsky(_at_)gmail(_dot_)com 
<mailto:gregimirsky(_at_)gmail(_dot_)com>>; Les
    Ginsberg (ginsberg) <ginsberg(_at_)cisco(_dot_)com 
<mailto:ginsberg(_at_)cisco(_dot_)com>>
    *Cc:* Robert Sparks <rjsparks(_at_)nostrum(_dot_)com
    <mailto:rjsparks(_at_)nostrum(_dot_)com>>; mpls(_at_)ietf(_dot_)org
    <mailto:mpls(_at_)ietf(_dot_)org>; gen-art(_at_)ietf(_dot_)org
    <mailto:gen-art(_at_)ietf(_dot_)org>;
    draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
    <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>;
    ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>; 
isis-chairs(_at_)ietf(_dot_)org
    <mailto:isis-chairs(_at_)ietf(_dot_)org>; Abhay Roy (akr) 
<akr(_at_)cisco(_dot_)com
    <mailto:akr(_at_)cisco(_dot_)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(_dot_)Vainshtein(_at_)ecitele(_dot_)com
    <mailto:Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com>>
    *Date: *Thursday, January 19, 2017 at 10:15 AM
    *To: *Greg Mirsky <gregimirsky(_at_)gmail(_dot_)com
    <mailto:gregimirsky(_at_)gmail(_dot_)com>>, "Les Ginsberg (ginsberg)"
    <ginsberg(_at_)cisco(_dot_)com <mailto:ginsberg(_at_)cisco(_dot_)com>>
    *Cc: *Acee Lindem <acee(_at_)cisco(_dot_)com 
<mailto:acee(_at_)cisco(_dot_)com>>, Robert
    Sparks <rjsparks(_at_)nostrum(_dot_)com 
<mailto:rjsparks(_at_)nostrum(_dot_)com>>,
    "mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>" 
<mpls(_at_)ietf(_dot_)org
    <mailto:mpls(_at_)ietf(_dot_)org>>, "gen-art(_at_)ietf(_dot_)org
    <mailto:gen-art(_at_)ietf(_dot_)org>" <gen-art(_at_)ietf(_dot_)org
    <mailto:gen-art(_at_)ietf(_dot_)org>>,
    "draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
    <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>"
    <draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
    <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>>,
    "ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>" 
<ietf(_at_)ietf(_dot_)org
    <mailto:ietf(_at_)ietf(_dot_)org>>, "isis-chairs(_at_)ietf(_dot_)org
    <mailto:isis-chairs(_at_)ietf(_dot_)org>" <isis-chairs(_at_)ietf(_dot_)org
    <mailto:isis-chairs(_at_)ietf(_dot_)org>>, "Abhay Roy (akr)" 
<akr(_at_)cisco(_dot_)com
    <mailto:akr(_at_)cisco(_dot_)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(_dot_)Vainshtein(_at_)ecitele(_dot_)com
        <mailto:Alexander(_dot_)Vainshtein(_at_)ecitele(_dot_)com>

        *From:*Greg Mirsky [mailto:gregimirsky(_at_)gmail(_dot_)com]
        *Sent:* Thursday, January 19, 2017 6:01 PM
        *To:* Les Ginsberg (ginsberg) <ginsberg(_at_)cisco(_dot_)com
        <mailto:ginsberg(_at_)cisco(_dot_)com>>
        *Cc:* Acee Lindem (acee) <acee(_at_)cisco(_dot_)com
        <mailto:acee(_at_)cisco(_dot_)com>>; Robert Sparks 
<rjsparks(_at_)nostrum(_dot_)com
        <mailto:rjsparks(_at_)nostrum(_dot_)com>>; mpls(_at_)ietf(_dot_)org
        <mailto:mpls(_at_)ietf(_dot_)org>; gen-art(_at_)ietf(_dot_)org
        <mailto:gen-art(_at_)ietf(_dot_)org>;
        draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
        <mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>;
        ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>; 
isis-chairs(_at_)ietf(_dot_)org
        <mailto:isis-chairs(_at_)ietf(_dot_)org>; Abhay Roy (akr) 
<akr(_at_)cisco(_dot_)com
        <mailto:akr(_at_)cisco(_dot_)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(_at_)cisco(_dot_)com <mailto:ginsberg(_at_)cisco(_dot_)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(_at_)gmail(_dot_)com
            <mailto:gregimirsky(_at_)gmail(_dot_)com>]
            *Sent:* Thursday, January 19, 2017 7:44 AM
            *To:* Acee Lindem (acee)
            *Cc:* Robert Sparks; mpls(_at_)ietf(_dot_)org 
<mailto:mpls(_at_)ietf(_dot_)org>;
            gen-art(_at_)ietf(_dot_)org <mailto:gen-art(_at_)ietf(_dot_)org>;
            draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
            
<mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>;
            ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>; Les 
Ginsberg
            (ginsberg); isis-chairs(_at_)ietf(_dot_)org
            <mailto:isis-chairs(_at_)ietf(_dot_)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(_at_)cisco(_dot_)com <mailto:acee(_at_)cisco(_dot_)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(_at_)ietf(_dot_)org
            <mailto:mpls-bounces(_at_)ietf(_dot_)org>> on behalf of Greg Mirsky
            <gregimirsky(_at_)gmail(_dot_)com 
<mailto:gregimirsky(_at_)gmail(_dot_)com>>
            *Date: *Wednesday, January 18, 2017 at 1:25 PM
            *To: *Robert Sparks <rjsparks(_at_)nostrum(_dot_)com
            <mailto:rjsparks(_at_)nostrum(_dot_)com>>
            *Cc: *"mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>"
            <mpls(_at_)ietf(_dot_)org <mailto:mpls(_at_)ietf(_dot_)org>>, 
"gen-art(_at_)ietf(_dot_)org
            <mailto:gen-art(_at_)ietf(_dot_)org>" <gen-art(_at_)ietf(_dot_)org
            <mailto:gen-art(_at_)ietf(_dot_)org>>,
            "draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
            
<mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>"
            <draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org
            
<mailto:draft-ietf-mpls-residence-time(_dot_)all(_at_)ietf(_dot_)org>>,
            "ietf(_at_)ietf(_dot_)org <mailto:ietf(_at_)ietf(_dot_)org>" 
<ietf(_at_)ietf(_dot_)org
            <mailto:ietf(_at_)ietf(_dot_)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(_at_)nostrum(_dot_)com 
<mailto:rjsparks(_at_)nostrum(_dot_)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(_at_)gmail(_dot_)com
                    <mailto:gregimirsky(_at_)gmail(_dot_)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(_at_)nostrum(_dot_)com
                    <mailto:rjsparks(_at_)nostrum(_dot_)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].


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