[OSPF] RE: [Isis-wg] CCAMP Working group last call ondraft-ietf-ccamp-te-node-cap-02.txt

"Les Ginsberg \(ginsberg\)" <ginsberg@cisco.com> Sun, 22 October 2006 06:36 UTC

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Date: Sat, 21 Oct 2006 23:36:42 -0700
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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Adrian Farrel <adrian@olddog.co.uk>, isis-wg@ietf.org, ospf@ietf.org, mpls@lists.ietf.org
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Cc: routing-discussion@ietf.org
Subject: [OSPF] RE: [Isis-wg] CCAMP Working group last call ondraft-ietf-ccamp-te-node-cap-02.txt
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In regards to the IS-IS definitions, there is (again - sorry JP...)
confusion in the use of the terms TLV and subTLV.

For example, in Section 2 it states:

A new TLV is defined for ISIS and OSPF: the TE Node Capability 
   Descriptor TLV, to be carried within: 
        - The ISIS Capability TLV ([ISIS-CAP]) for ISIS...
<end snip>

If the information is carried within another TLV, then it is clearly
subTLV information - the difference between the two is more than
terminology since it impacts both the encoding and the scope of the
identifiers which are assigned.

Section 4.2 then goes on to discuss:

"The format of the IS-IS TE Node Capability TLV" - which is, as pointed
out above, actually a subTLV.

And then goes on to define "subsubTLVs" (which are incorrectly called

As "subsubTLVs" are new to IS-IS encoding some discussion of this added
level of hierarchy is required. However, I think it might also be fair
to entertain the possibility that the "TE Node Capability subTLV" be
deleted and the "subsubTLVs" defined in the subsections of 4.2 be
defined more directly as subTLVs of the IS-IS CAPs TLV. This is possible
because as currently defined, the "TE Node Capability subTLV" has no
information at the subTLV level - it is simply a container for the
subsubTLV information. This would allow for a more efficient encoding
without any loss of functionality.

Whatever the resolution, all the text relating to this must be reworded
to be consistent and accurate.

I would also prefer that the wording of the following sentence in
Section 5.2:

"An empty TE Node Capability Descriptor MUST be discarded."

be changed to

"An empty TE Node Capability Descriptor MUST be ignored."

The term "discard" suggests that a router which leaks a CAP TLV
containing TE node capability information might be required to modify
the contents of that TLV - which is something to be avoided.


> -----Original Message-----
> From: Adrian Farrel [mailto:adrian@olddog.co.uk]
> Sent: Saturday, October 21, 2006 5:22 AM
> To: isis-wg@ietf.org; ospf@ietf.org; mpls@lists.ietf.org
> Cc: Brungard, Deborah A, ALABS; routing-discussion@ietf.org
> Subject: [Isis-wg] CCAMP Working group last call
> node-cap-02.txt
> Heads up.
> The CCAMP working group is holding a working group last call on this
> draft.
> Your input is invited.
> Please send comments direct to the CCAMP mailing list or to the WG
> (Deborah and/or me) if you are not subscribed to CCAMP.
> Thanks,
> Adrian
> ----- Original Message -----
> From: "Adrian Farrel" <adrian@olddog.co.uk>
> To: <ccamp@ops.ietf.org>
> Sent: Tuesday, October 17, 2006 1:34 AM
> Subject: Working group last call on
> > This starts a two week working group last on
> >
> >
> > Please send your comments to the CCAMP mailing list by 12 midnight
> time
> > on Monday 30th October
> >
> > Thanks,
> > Adrian and Deborah
> _______________________________________________
> Isis-wg mailing list
> Isis-wg@ietf.org
> https://www1.ietf.org/mailman/listinfo/isis-wg

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