Re: [ippm] Mail regarding draft-fz-6man-ipv6-alt-mark

Tianran,

Also in this document you state:
   The desired choice is to define a new Extension Header.
   [I-D.zhou-ippm-enhanced-alternate-marking] generalizes the data
   fields for the alternate marking method and inspired the layout.

But then it seems that you define a new TLV (aka option) for the HBH and DestOpt EHs. Is that correct?
If so it might be worth making that clear in the document. Now it reads in some places like you are proposing to create a new extension header.
Which we in general are not in favour of, given that we have three generic "container" EHs already. And tht we have text in 8200 strongly recommending against creating new EHs with hop by hop behaviour.

Best regards,
Ole

> On 23 Oct 2019, at 03:19, Tianran Zhou <zhoutianran@huawei.com> wrote:
> 
> Hi Bob,
> 
> Thank you very much for your suggestion. I agree.
> We will update this in the next revision.
> 
> BR,
> Tianran
> 
>> -----Original Message-----
>> From: Bob Hinden [mailto:bob.hinden@gmail.com]
>> Sent: Tuesday, October 22, 2019 11:33 PM
>> To: Tianran Zhou <zhoutianran@huawei.com>
>> Cc: Bob Hinden <bob.hinden@gmail.com>; Giuseppe Fioccola
>> <giuseppe.fioccola@huawei.com>; IPv6 List <ipv6@ietf.org>; IETF IPPM WG
>> <ippm@ietf.org>; Tom Herbert <tom@quantonium.net>; Haoyu Song
>> <haoyu.song@futurewei.com>; draft-fz-6man-ipv6-alt-mark@ietf.org
>> Subject: Re: [ippm] Mail regarding draft-fz-6man-ipv6-alt-mark
>> 
>> Tianran,
>> 
>> 
>>> On Oct 21, 2019, at 9:04 PM, Tianran Zhou <zhoutianran@huawei.com> wrote:
>>> 
>>> Hi Bob,
>>> 
>>> Thanks for your comments.
>>> On this:
>>> " In the EH definition in Section 3.1.1 there is a field called "Flow ID".
>> I can’t tell if this is the same or different from the IPv6 flow label defined
>> in RFC8200 and RFC6437.   This should be clarified and justified."
>>> 
>>> Here are my thoughts:
>>> 1. The flow label in rfc8200 is used for application service, like LB/ECMP,
>> QoS. The flow ID used in the EH is to identify the monitored flow, and may
>> be assigned by a controller. That is to say, flow label and flow ID within
>> the same packet will have different scope, identify different flows,
>> different usage. So it's better to separate the two.
>>> 2. The flow ID is used for monitoring and measurement. The reuse of flow
>> label field may change the application intent(e.g.ECMP) and forwarding
>> behavior. So that the measurement does not align with the original traffic.
>>> 3. The flow label may be changed en route. The reuse of the flow label field
>> for the flow ID may violate the measurement task.
>> 
>> The issue I raised is that because the names are similar, it is easy to confuse
>> the two.  If this is different, the draft needs to be much clearer on its
>> definition.  For example, the draft doesn’t include most of the text you wrote
>> above.
>> 
>> I would also suggest a different name so it won’t be confused.  For example,
>> “measurement ID”, or similar.
>> 
>> Bob
>> 
>> 
>>> 
>>> Any thoughts?
>>> 
>>> Best,
>>> Tianran
>>>> -----Original Message-----
>>>> From: ipv6 [mailto:ipv6-bounces@ietf.org] On Behalf Of Giuseppe
>>>> Fioccola
>>>> Sent: Monday, October 21, 2019 9:30 PM
>>>> To: Bob Hinden <bob.hinden@gmail.com>; IPv6 List <ipv6@ietf.org>;
>>>> IETF IPPM WG <ippm@ietf.org>; Tom Herbert <tom@quantonium.net>
>>>> Cc: Haoyu Song <haoyu.song@futurewei.com>;
>>>> draft-fz-6man-ipv6-alt-mark@ietf.org
>>>> Subject: RE: [ippm] Mail regarding draft-fz-6man-ipv6-alt-mark
>>>> 
>>>> Dear Bob, Tom,
>>>> Thanks a lot for your review of the draft. Much appreciate.
>>>> Please find my answers inline tagged as [GF].
>>>> 
>>>> Best Regards,
>>>> 
>>>> Giuseppe
>>>> 
>>>> -----Original Message-----
>>>> From: Bob Hinden [mailto:bob.hinden@gmail.com]
>>>> Sent: Saturday, October 19, 2019 7:08 PM
>>>> To: IPv6 List <ipv6@ietf.org>; IETF IPPM WG <ippm@ietf.org>
>>>> Cc: Bob Hinden <bob.hinden@gmail.com>; Haoyu Song
>>>> <haoyu.song@futurewei.com>; draft-fz-6man-ipv6-alt-mark@ietf.org; Tom
>>>> Herbert <tom@quantonium.net>
>>>> Subject: Re: [ippm] Mail regarding draft-fz-6man-ipv6-alt-mark
>>>> 
>>>> Hi,
>>>> 
>>>> I did a quick read of this draft and have a few comments.
>>>> 
>>>> It appears to be defining a new IPv6 extension header.   It should say
>> that
>>>> in the title and be described in the abstract.
>>>> 
>>>> [GF]: I will do.
>>>> 
>>>>  This document defines how the alternate marking method can be used to
>>>>  measure packet loss and delay metrics of IPv6 and SRv6.
>>>> 
>>>> As Tom mentioned, SRv6 is part of IPv6, they are not separate things.
>>>> 
>>>> [GF]: Sure, we meant that it can be applicable to IPv6 and, as a
>>>> consequence, also to SRv6. We will specify it better in the next revision.
>>>> 
>>>>  The IPv6 Header Format defined in [RFC8200] introduces the format of
>>>>  the IPv6 addresses, the Extension Headers in the base IPv6 Header and
>>>>  the availability of a 20-bit flow label, that can be considered for
>>>>  the application of the Alternate Marking methodology.  In this
>>>> 
>>>> RFC8200 does not define the format of IPv6 addresses.  That is done
>>>> in RFC4291.
>>>> 
>>>> [GF]: Yes, we will add the reference to RFC4291.
>>>> 
>>>> This draft appears to depend on a number of IPPM documents, but none
>>>> are listed as normative references.
>>>> 
>>>> [GF]: We will review the dependencies. In particular we may need to
>>>> cut the reference to draft-zhou-ippm-enhanced-alternate-marking and
>>>> leave only RFC
>>>> 8321 and draft-ietf-ippm-multipoint-alt-mark.
>>>> 
>>>> One of these is RFC 8321, but that has status of Experimental.  I
>>>> don’t think this document can be Standards track if it depends on an
>> Experimental RFC.
>>>> 
>>>> [GF]: Consider that RFC 8321 was classified as Experimental since it
>>>> describes a methodology that came from lab experience. In particular,
>>>> the first example of application was with IP packets where there is
>>>> no space for marking and we reused the DSCP field for our scope.
>>>> However the applicability of the method is general and, in this
>>>> draft, the new IPv6 extension header introduces an appropriate
>>>> marking field that would be dedicated only for the alternate marking
>>>> method and not for other purposes. So we refer to RFC 8321 just for
>>>> information and this does not necessarily imply that the draft should be
>> experimental, therefore it could be discussed.
>>>> 
>>>> In the EH definition in Section 3.1.1 there is a field called "Flow
>>>> ID".  I can’t tell if this is the same or different from the IPv6 flow
>> label defined
>>>> in RFC8200 and RFC6437.   This should be clarified and justified.
>>>> 
>>>> [GF]: Of course, it is a separate field and we will make it clearer
>>>> in the next version.
>>>> 
>>>> Bob
>>>> 
>>>> 
>>>> 
>>>>> On Oct 19, 2019, at 8:32 AM, Tom Herbert <tom@quantonium.net> wrote:
>>>>> 
>>>>> On Fri, Oct 18, 2019 at 1:30 AM Haoyu Song <haoyu.song@futurewei.com>
>> wrote:
>>>>>> 
>>>>>> I just read this draft and I think it’s an implementation of the
>>>>>> draft
>>>> [I-D.zhou-ippm-enhanced-alternate-marking], which discusses the
>>>> method of encapsulating the enhanced alternate marking header in
>>>> IPv6. I have several comments.
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> It doesn’t cover the encapsulation on SRv6 yet and I think a
>>>>>> solution for
>>>> SRv6 would be more useful.
>>>>> 
>>>>> SRv6 _is_ a subset IPv6. It is one type of routing header. Like any
>>>>> other use case of IPv6, HBH and destination options are useable when
>>>>> SRv6 header is present. Because SRv6 is a routing header destination
>>>>> options before the routing header are processed by each destination
>>>>> in the route list.
>>>>> 
>>>>>> More deployment consideration discussion should be given when it’s
>>>>>> encapsulated in HBH EH
>>>>> 
>>>>> In what regard?
>>>>> 
>>>>>> The document mentioned two PBT modes discussed in
>>>> [I-D.song-ippm-postcard-based-telemetry]. Since the PBT-I variation
>>>> has been merged in another draft
>>>> [I-D.ioamteam-ippm-ioam-direct-export], this draft may need to be updated
>> accordingly.
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Thanks!
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Haoyu
>>>>>> 
>>>>>> _______________________________________________
>>>>>> ippm mailing list
>>>>>> ippm@ietf.org
>>>>>> https://www.ietf.org/mailman/listinfo/ippm
>>>>> 
>>>>> --------------------------------------------------------------------
>>>>> IETF IPv6 working group mailing list ipv6@ietf.org Administrative
>>>>> Requests: https://www.ietf.org/mailman/listinfo/ipv6
>>>>> --------------------------------------------------------------------
>>>> 
>>>> --------------------------------------------------------------------
>>>> IETF IPv6 working group mailing list
>>>> ipv6@ietf.org
>>>> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
>>>> --------------------------------------------------------------------
> 
> --------------------------------------------------------------------
> IETF IPv6 working group mailing list
> ipv6@ietf.org
> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> --------------------------------------------------------------------