[mpls] MPLS-RT experts review for draft-gandhi-mpls-rfc6374-sr

Xufeng Liu <xufeng.liu.ietf@gmail.com> Wed, 17 June 2020 17:10 UTC

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From: Xufeng Liu <xufeng.liu.ietf@gmail.com>
Date: Wed, 17 Jun 2020 13:10:27 -0400
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To: Tarek Saad <tsaad.net@gmail.com>, mpls@ietf.org
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Subject: [mpls] MPLS-RT experts review for draft-gandhi-mpls-rfc6374-sr
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Hi Authors and WG,

I have reviewed the document draft-gandhi-mpls-rfc6374-sr and have the
following comments.

1. Using the existing mechanism defined by RFC 6374 for SR PM is natural,
logical, and worth proceeding.

2. The 2nd paragraph in Sec 2.3 describes the case P2MP, but the context is
the reference topology depicted as Figure 2, which does not clearly cover
the P2MP case. Some additional clarification or a different topology may
illustrate better.

3. In the last paragraph in Sec 4.2 describes the use of Destination
Address TLV. Does the statement “can be sent in the probe query message”
mean that this is optional? (Is this MAY or MUST?) An implementer would
like to know the clear requirement.

4. Sec 4.3.3. describes the loopback measure mode, which requires the
responder to collect timestamps t1 and t4. Such a behavior does not seem to
follow RFC 6374. Based on Sec 3.5.3. of RFC 6374, “no support for delay
measurement is required at the responder at all, other than the ability to
recognize a DM query that includes this object and return it unmodified.”

5. The last sentence of Sec 4.3.3. excludes the loopback mode for SR-MPLS
Links. Is there any reason for the exclusion?

6. Most of the document describes the procedures to use RFC 6374. The only
additions to RFC 6374 are Sec. 4.4. and Sec. 6.2., but these two sections
are embedded in the other sections on procedures and use cases. For an
implementer, I’d hope to see these two sections separated from others so
that it would be clear what are needed to implement on top of the protocol
defined in RFC 6374.


- Xufeng