Subject: [Gen-art] Gen-ART Last Call review of draft-ietf-ccamp-rsvp-te-mpls-tp-oam-ext-14

From: Brian E Carpenter <[email-masked]>
Date: Thu, 01 Jan 2015 11:07:02 +1300

I am the assigned Gen-ART reviewer for this draft. For background on
Gen-ART, please see the FAQ at
<http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.

Please resolve these comments along with any other Last Call comments
you may receive.

Document: draft-ietf-ccamp-rsvp-te-mpls-tp-oam-ext-14.txt
Reviewer: Brian Carpenter
Review Date: 2015-01-01
IETF LC End Date: 2015-01-08
IESG Telechat date:

Summary: Almost ready
--------

Major issue:
------------

In "3.1.3.  Configuration of Fault Management Signals":

"  If an
   implementation wishes to modify... "

"   However, by setting the "Fault Management subscription" flag in the
   "MPLS OAM FMS sub-TLV", a client LSP can indicate that it would like
   an association to be created to the server MEP(s) on any intermediate
   nodes."

I find "wishes" and "would like" to be very strange verbs. Do they
refer to operator choices or programmer choices? Implementations
and client LSPs don't have a faculty of choice. Please clarify which
human is making a choice and what the default is.

There are a few other places where words like "desire" and "intend"
are used of objects, not of humans. I think all of these need to be
clarified in terms of what is the default behaviour, whether it is set
by the programmer or by the operator, and how it is changed (by an
NMS for example). Otherwise the spec seems to call for intelligent
devices or for magic.

Minor issues:
-------------

In "3.1.  MPLS-TP OAM Configuration Operation Overview":

"  ... If placed in LSP_ATTRIBUTES nodes that are not
   able to process the OAM Configuration TLV will forward the message
   without generating an error, this is not the case if placed in the
   LSP_REQUIRED_ATTRIBUTES object."

Grammar: the comma should be a semi-colon or a period.

Technical: Does this mean that an error MUST be generated if the MPLS
OAM FMS sub-TLV is in a LSP_REQUIRED_ATTRIBUTES object in such a node?
If so, please say so clearly.

In "3.2.1.  CV Flag Rules of Use":

"  Moreover, if the CV flag is set, the CC flag MUST be set as well as
   performing Connectivity Verification implies performing Continuity
   Check. "

Please fix the syntax. I can see several possible meanings for this
sentence. Maybe it means:

   If the CV flag is set, the CC flag MUST also be set, because
   performing Connectivity Verification implies performing Continuity
   Check as well.

" The format of an MPLS-TP CV/CC message is shown in [RFC6428]
   and it requires, together with the BFD Control packet information,
   the "LSP MEP-ID". "

Ditto. I'm guessing this means:

   The format of an MPLS-TP CV/CC message is shown in [RFC6428].
   It MUST contain the BFD Control packet information and the
   "LSP MEP-ID".

In "8.  Security Considerations":

"  In particular, a
   network element could be overloaded if an attacker were to request
   high frequency liveliness monitoring ..."

So would it be appropriate to recommend some kind of rate limits on
liveliness monitoring?

Nits:
-----

In "3.2.  MPLS OAM Configuration sub-TLV"

"     Then all OAM functions that
      have their corresponding flags set in the ?OAM Function Flags sub-
      TLV?  MUST be assigned their default values or left disabled."

 The "?" marks must be an error.

I noted one comma error above that is confusing. Actually there are
numerous comma errors: missing commas, unnecessary commas, and commas
that should be semi-colons or periods. Hopefully the RFC Editor will
catch them.