Re: [sfc] IETF WG state changed for draft-ietf-sfc-proof-of-transit

Dear Authors, Chairs, et al.,
I've read and reviewed the latest version of the draft. The document is
well-written and addresses the essential problem in a very elegant manner.
I have several questions on the applicability of the proposed solution to
SFC NSH:

   - several technologies listed in the Introduction

   Several deployments use Traffic Engineering, policy routing, Segment
   Routing (SR), and Service Function Chaining (SFC) [RFC7665] to steer
   packets through a specific set of nodes.

I think that adding more references to IETF documents that defined the
technology, e.g. RFC 8402, RFC 8595, would benefit the text.

   -  as noted above, the document mentions a number of techniques to steer
   a flow over the particular path, including SFC NSH. That does make lots of
   sense for the Introduction but, since this is SFC WG document, one can
   expect more information on how POT can be used in SFC NSH environment. It
   would certainly be beneficial to provide as an example of carrying POT data
   using some of these methods? I think that for the SFC WG SFC NSH is the
   most desirable example.  Currently, some pieces of information can be found
   in draft-ietf-ippm-ioam-data and some in draft-ietf-sfc-ioam-nsh. I've
   tried to put them all together for SFC NSH but I don't think that I've got
   the puzzle together. I appreciate it if you can help me understand (likely
   I've missed it in one of the drafts) which elements of an SFC, i.e. SFF,
   SF/SF Proxy, Classifier, are POT-acting nodes? Also, are there requirements
   for SFC elements specific to POT?
   - looking at section 4.5 draft-ietf-ippm-ioam-data
   <https://tools.ietf.org/html/draft-ietf-ippm-ioam-data-09#section-4.5> I
   think that it limits the number of POT profiles that are used to calculate
   the Cumulative on a node to two. profile-index-range is defined as 0,1 but
   without the reference, it is not easy to understand the reason for the
   limitation. This is probably just one example where the additional
   reference in YANG data model will be helpful (I've noticed only one and it
   is empty).
   - continuing on pot-profile-index, how it is used in the SFC
   environment? And what ensures that all POT nodes along the SFP have a
   consistent view of POT profiles.

Regards,
Greg

On Tue, Jun 16, 2020 at 6:42 AM Joel M. Halpern <jmh@joelhalpern.com> wrote:

> The chairs are starting the WG last call for
> draft-ietf-sfc-proof-of-transit.  Please reply explicitly whether you
> think this is ready to go to the IETF for publication as a Experimental
> RFC.
> As noted below, the call runs through June 30.
>
> Note that silence does not imply consent, so please speak up.
>
> Yours,
> Joel (& Jim)
>
> On 6/16/2020 9:32 AM, IETF Secretariat wrote:
> >
> > The IETF WG state of draft-ietf-sfc-proof-of-transit has been changed to
> "In
> > WG Last Call" from "WG Document" by Joel Halpern:
> >
> > https://datatracker.ietf.org/doc/draft-ietf-sfc-proof-of-transit/
> >
> > Comment:
> > This starts WG last call for this document, ending June 30.
> >
>
> _______________________________________________
> sfc mailing list
> sfc@ietf.org
> https://www.ietf.org/mailman/listinfo/sfc
>