Subject: [mpls] MPLS-RT review of draft-mirsky-mpls-p2mp-bfd-04

From: "Andrew G. Malis" <[email-masked]>
Date: Wed, 24 Oct 2018 12:17:11 -0400

I’ve been selected as an MPLS-RT reviewer for
draft-mirsky-mpls-p2mp-bfd-04, which is currently a candidate for MPLS WG
adoption. This draft documents procedures for using BFD for multipoint
networks to detect data plane failures in MPLS p2mp LSPs.

The BFD WG has been working on draft-ietf-bfd-multipoint, which describes
BFD procedures for multipoint and multicast networks.
draft-mirsky-mpls-p2mp-bfd uses that draft as a basis to detect MPLS data
plane failures for p2mp LSPs. This is a straightforward and useful
application of the BFD draft for MPLS data plane failure detection.

However, I would have expected to see at least a reference to RFC 4687,
"Operations and Management (OAM) Requirements for Point-to-Multipoint MPLS
Networks", and some text on how this draft addresses the requirements in
that draft.

I also expected more text on the relationship between this draft and RFC
6425, "Detecting Data-Plane Failures in Point-to-Multipoint MPLS -
Extensions to LSP Ping"', and more of an explanation of why the keyword MAY
is used in sections 4.1 and 4.2 - what are the implications of following or
not following the MAY in each case?

The draft also needs an editing pass, for example "MaultipointHead"
for "MultipointHead"
and some incorrect English grammar in several places.

Once these items have been addressed, I think that the draft should be
ready for an adoption call.

Cheers,
Andy

---

From: Greg Mirsky <[email-masked]>
Date: Wed, 24 Oct 2018 11:11:49 -0700

Dear Andy,
thank you for your thorough review and the most helpful comments. I'll work
on the update to address them.

Regards,
Greg

On Wed, Oct 24, 2018 at 9:17 AM Andrew G. Malis <[email-masked]> wrote:

> The draft also needs an editing pass, for example "MaultipointHead" for "MultipointHead"

---

From: Greg Mirsky <[email-masked]>
Date: Tue, 30 Oct 2018 08:05:28 -0700

Dear Andy,
thank you for the review and the detailed suggestions. Attached please find
the updated version of the draft and the diff to highlight the proposed
changes. Please let me know if these address your comments.

Kind regards,
Greg

On Wed, Oct 24, 2018 at 11:11 AM Greg Mirsky <[email-masked]> wrote:

> Dear Andy,
> thank you for your thorough review and the most helpful comments. I'll
> work on the update to address them.
>
> Regards,
> Greg
>

---

From: "Andrew G. Malis" <[email-masked]>
Date: Wed, 31 Oct 2018 09:40:49 -0400

Greg,

Thanks for checking.

You didn't really address my comment: "I would have expected to see at
least a reference to RFC 4687, "Operations and Management (OAM)
Requirements for Point-to-Multipoint MPLS Networks", and some text on how
this draft addresses the requirements in that draft.".

You added a reference in the security section, but nothing about how your
draft addresses the 4687 requirements.

Also, you didn't really address my next comment: "I also expected more text
on the relationship between this draft and RFC 6425, "Detecting Data-Plane
Failures in Point-to-Multipoint MPLS - Extensions to LSP Ping"', and more
of an explanation of why the keyword MAY is used in sections 4.1 and 4.2 -
what are the implications of following or not following the MAY in each
case?"

Regarding RFC 6425, I was looking for text along the lines of why one would
choose to implement this draft rather than 6425 (or both), to give product
implementers and network operators guidance on whether to use 6425, this
draft, or both for MPLS p2mp data plane failure detection. Otherwise, why
would they bother with this draft when they already have 6425 working?

Also, in sections 4.1 and 4.2, you just added another MAY to section 4.1,
but again, what happens if you don't do the MAYs in both sections? Why
would I want to do the MAYs? Why would I not want to? The text doesn't say.

Finally, in section 3, the following sentence doesn't scan:

   The source IP
   address MAY be drawn from the IP header if BFD control packet
   transmitted by the head using IP/UDP encapsulation as described in
   Section 3.1.

Did you mean "uses" instead of "using"?

Thanks,
Andy

On Tue, Oct 30, 2018 at 11:05 AM Greg Mirsky <[email-masked]> wrote:

> Dear Andy,
> thank you for the review and the detailed suggestions. Attached please
> find the updated version of the draft and the diff to highlight the
> proposed changes. Please let me know if these address your comments.
>
> Kind regards,
> Greg
>
>>> The BFD WG has been working on draft-ietf-bfd-multipoint, which
>>> describes BFD procedures for multipoint and multicast networks.
>>> The draft also needs an editing pass, for example "MaultipointHead" for
>>> "MultipointHead" and some incorrect English grammar in several places.
>>>