Re: [mpls] MPLS-RT Review of draft-gandhi-mpls-ioam-sr-04

Rakesh,

Thanks, sounds good!

Cheers,
Andy

On Mon, Dec 28, 2020 at 8:32 PM Rakesh Gandhi <rgandhi.ietf@gmail.com>
wrote:

> Thanks Andy, Loa and Greg.
> Acking, we can go with a similar ACH based proposal.
>
> Thanks,
> Rakesh
>
>
> On Mon, Dec 28, 2020 at 2:05 PM Andrew G. Malis <agmalis@gmail.com> wrote:
>
>> Greg,
>>
>> Thanks for the reminder! This is basically what I had in mind when I
>> suggested using the ACH.
>>
>> Cheers,
>> Andy
>>
>>
>> On Mon, Dec 28, 2020 at 12:31 PM Greg Mirsky <gregimirsky@gmail.com>
>> wrote:
>>
>>> Hi Loa, Andy, et al.,
>>> I think that if someone is interested in how a similar problem (as I
>>> understand what IOAM tries to achieve) was resolved, RFC 8169
>>> <https://datatracker.ietf.org/doc/rfc8169/?include_text=1> might have
>>> useful information. We've used ACH, Scratch Pad for collecting telemetry
>>> (residence time), and TLV to carry the original PTP packet through the MPLS
>>> domain.
>>>
>>> Regards,
>>> Greg
>>>
>>> On Sun, Dec 27, 2020 at 11:04 PM Loa Andersson <loa@pi.nu> wrote:
>>>
>>>> Working Group,
>>>>
>>>> Andy and I have discussed this a bit off-line.
>>>>
>>>> Andy,
>>>>
>>>> I have now re-read the this  draft, other relevant drafts and the mail
>>>> we have exchanged. I had earlier partly misunderstood and now think
>>>> that
>>>> your summary of the situation is basically correct.
>>>>
>>>> However, I'd like to see more discussion on what we should do. In
>>>> particular I'd like to see a comment from the authors on this.
>>>>
>>>> You outline three different proposals:
>>>>
>>>> 1.  follow the draft and allocate 0x0010b from IP Version Numbers
>>>>      registry in the Version Numbers name space for this purpose
>>>> 2.  use ACH
>>>> 3.  use code point #15 from IP Version Numbers registry in the Version
>>>>     Numbers name space
>>>>
>>>> To me it seems like 1 and 3 is the same, we ask for a code point from
>>>> IP
>>>> Version Numbers registry in the Version Numbers name space. IANA pick
>>>> the code point for us.
>>>>
>>>> Note 1: We can give a strong recommendation telling IANA which code
>>>> point we want, but the decision is still with IANA.
>>>>
>>>> Note 2: It seems like the chances that a Version number lower than 6
>>>> will not be picked for an IP version, value 2 is unassigned and much
>>>> easier to allocate than the reserved value 15.
>>>>
>>>> Note 3: I think you are right that it is a hrd sell both to working
>>>> group and the IESG to pick a value from this registry.
>>>>
>>>> Authors.
>>>>
>>>> It would be nice to hear from you on this discussion, but don't change
>>>> the document until we have a reasonable consensus.
>>>>
>>>> /Loa
>>>>
>>>>
>>>>
>>>> On 25/12/2020 01:44, Andrew G. Malis wrote:
>>>> > I've been asked to provide a pre-adoption MPLS-RT review of
>>>> > draft-gandhi-mpls-ioam-sr-04.
>>>> >
>>>> > I have a major concern that I believe needs to be addressed, either
>>>> > before or after WG adoption (I defer to the WG chairs to make this
>>>> > decision). My personal preference is that it be addressed by the
>>>> authors
>>>> > prior to adoption, but if it occurs following adoption, I would like
>>>> to
>>>> > see it addressed before it gets much further in the WG process.
>>>> >
>>>> > My concern is as follows:
>>>> >
>>>> > In Section 6 and Figure 1, 0x0010b (2 decimal) is used for the first
>>>> > nibble following the MPLS label stack in order to avoid ECMP. This
>>>> > intent is fine, but there is an issue with choosing this particular
>>>> > value. The first nibble following the label stack is often (as we
>>>> know)
>>>> > interpreted as an IP Version Number. According to
>>>> >
>>>> https://www.iana.org/assignments/version-numbers/version-numbers.xhtml
>>>> > <
>>>> https://www.iana.org/assignments/version-numbers/version-numbers.xhtml>
>>>>
>>>> > , 0x0010b (2 decimal) is currently unassigned, so it COULD be
>>>> assigned
>>>> > by IANA, creating a future conflict.
>>>> >
>>>> > We could request IANA to assign IP Version number 2 for this purpose,
>>>> > but I believe that would be a very difficult sell to both IANA and
>>>> the
>>>> > IESG, as there are only a small number of IP Version numbers
>>>> available.
>>>> >
>>>> > Instead, I would suggest either of the two following alternatives:
>>>> >
>>>> > 1. Use the MPLS ACH (RFC 5586), starting with 0x0001b, and alter the
>>>> > packet format in Figure 1 of this draft accordingly so that it
>>>> follows
>>>> > the ACH's general format but also includes the necessary fields for
>>>> the
>>>> > draft's purpose.
>>>> >
>>>> > 2. Use one of the IANA reserved IP version numbers instead of
>>>> 0x0010b. I
>>>> > would recommend 15 (0x1111b). There is reasonable certainty that this
>>>> > would never actually ever be assigned by IANA.
>>>> >
>>>> > The first alternative is my personal preference, but I would be OK
>>>> with
>>>> > the second as well.
>>>> >
>>>> > Other comments:
>>>> >
>>>> > Other than this issue, I found the draft to be well-written and easy
>>>> to
>>>> > follow, and generally ready for WG adoption.
>>>> >
>>>> > Cheers,
>>>> > Andy
>>>> >
>>>> >
>>>> > _______________________________________________
>>>> > mpls mailing list
>>>> > mpls@ietf.org
>>>> > https://www.ietf.org/mailman/listinfo/mpls
>>>> >
>>>>
>>>> --
>>>>
>>>> Loa Andersson                        email: loa@pi.nu
>>>> Senior MPLS Expert                          loa.pi.nu@gmail.com
>>>> Bronze Dragon Consulting             phone: +46 739 81 21 64
>>>>
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