Re: [mpls] [spring] to progress draft-cheng-spring-mpls-path-segment

Hi Weiqiang Cheng,
thank you for your expedient response to my questions. The document states
that one of the use cases for the Path segment is to be used as a
performance, packet loss and/or delay, measurement session identifier. I
think that RFC 6374 is the most suitable for PM OAM in SR-MPLS environment.
Of course, the type of the encapsulated message can be identified using the
destination UDP port number with IP/UDP encapsulation. But another option
is to use G-ACh encapsulation. That would require the use of GAL. And that
is how I've arrived at my original question (I should have explained it
better, my apologies):

How the Path segment and GAL are placed relative to each other in the
SR-MPLS label stack?

Regards,
Greg

On Fri, Feb 15, 2019 at 4:40 PM Weiqiang Cheng <
chengweiqiang@chinamobile.com> wrote:

> Hi Greg,
>
> Thanks a lot for your comments.
>
> My comments are in-line.
>
>
>
> B.R.
>
> Weiqiang Cheng
>
>
>
> *发件人:* Greg Mirsky [mailto:gregimirsky@gmail.com]
> *发送时间:* 2019年2月15日 3:37
> *收件人:* Alexander Vainshtein
> *抄送:* spring@ietf.org; Stewart Bryant;
> draft-cheng-spring-mpls-path-segment@ietf.org; mpls@ietf.org; Loa
> Andersson
> *主题:* Re: [spring] to progress draft-cheng-spring-mpls-path-segment
>
>
>
> Dear All,
>
> I concur with all what has been said in support of the adoption of this
> draft by SPRING WG. The document is well-written, addresses the real
> problem in SR-MPLS, and the proposed solution is technically viable.
>
> My comments and questions are entirely for further discussion:
>
>    - would the draft be expanded to demonstrate how "the Path Segment may
>    be used to identify an SR-MPLS Policy, its Candidate-Path (CP) or a SID
>    List (SL)"?
>
> [Weiqiang] Yes, It is necessary and we will add some text to demonstrate
> this in the future version.
>
>    - as many use cases for the Path Segment are related to OAM
>    operations, it would be helpful to expand on the use of GAL and the Path
>    Segment.
>
>        [Weiqiang] It is always helpful to have more use cases. However,
> The GAL is used today in MPLS-TP LSPs to flag the G-Ach and is used for OAM
> packets only while the Path segment is used for data packets for the each
> traffic flow. It is a little bit different.
>
> Regards,
>
> Greg
>
>
>
> On Thu, Feb 14, 2019 at 1:12 AM Alexander Vainshtein <
> Alexander.Vainshtein@ecitele.com> wrote:
>
> +1.
>
>
>
> I have been following this draft from its -00 revision. The current
> revision has resolved most of the issues I (and others) have been raised
> (e.g., elimination of excessive options).
>
>
>
> From my POV, in its current state the draft meets two basic requirements
> for the WG adoption:
>
> 1.       It addresses a real and relevant problem, namely the MPLS Flow
> Identification problem discussed in general in RFC 8372
> <https://tools.ietf.org/html/rfc8372> and scoped to SR-MPLS LSPs in this
> draft. Specifics of SR-MPLS include the need to provide end-to-end liveness
> check that is one of the requirements explicitly specified in Section 2 of RFC
> 8355 <https://tools.ietf.org/html/rfc8355>.
>
> 2.       It provides a reasonable (from my POV) approach to  solution of
> this problem.
>
>
>
> I also concur with Stewart’s comment about strong similarity between the
> approach taken in this draft for SR-MPLS and generic work in progress on
> synonymous flow labels
> <https://tools.ietf.org/html/draft-ietf-mpls-sfl-framework-04> that has
> been already adopted as a MPLS WG item.  To me this is yet another
> indication that the draft should be adopted.
>
>
>
> My 2c,
>
> Sasha
>
>
>
> Office: +972-39266302
>
> Cell:      +972-549266302
>
> Email:   Alexander.Vainshtein@ecitele.com
>
>
>
> -----Original Message-----
> From: spring <spring-bounces@ietf.org> On Behalf Of Stewart Bryant
> Sent: Wednesday, February 13, 2019 12:48 PM
> To: Loa Andersson <loa@pi..nu <loa@pi.nu>>; spring@ietf.org;
> draft-cheng-spring-mpls-path-segment@ietf.org
> Subject: Re: [spring] to progress draft-cheng-spring-mpls-path-segment
>
>
>
> I have just read the draft and agree that it should be adopted by the WG.
> It solves an important problem in instrumenting and protecting an SR path.
>
>
>
> It should be noted that we needed to do something very similar in
> mainstream MPLS via the synonymous label work which is already adopted.
>
> However SL did not address the SR case. We therefore need this path label
> work to be progressed.
>
>
>
> - Stewart
>
>
>
> On 10/02/2019 08:11, Loa Andersson wrote:
>
> > Working Group,
>
> >
>
> > I have reviewed draft-cheng-spring-mpls-path-segment and as far as I
>
> > can see, it is ready for wg adoption.
>
> >
>
> > There were some comments in Bangkok, but due to the many collisions
>
> > between working groups at that meeting I couldn't attend the SPRING
>
> > f2f.
>
> >
>
> > The minutes are not clear, but as far as I understand, there is
>
> > nothing that can't be resolved in the wg process.
>
> >
>
> > /Loa
>
>
>
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