[mpls] Issues with your use of TLV Type and sub-types in your draft

Eric Gray <eric.gray@ericsson.com> Thu, 28 October 2010 07:13 UTC

From: Eric Gray <eric.gray@ericsson.com>
To: George Swallow <swallow@cisco.com>, 'Nitin Bahadur' <nitinb@juniper.net>, Kireeti Kompella <kireeti@juniper.net>
Date: Thu, 28 Oct 2010 03:14:45 -0400
Thread-Topic: Issues with your use of TLV Type and sub-types in your draft
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Subject: [mpls] Issues with your use of TLV Type and sub-types in your draft
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George/Nitin/Kireeti,

    A comment on your draft, for information only, at this point.

    You have suggested a new TLV type (20) and 3 new TLV sub-types (1,
2 and 3) in your draft (draft-ietf-mpls-lsp-ping-enhanced-dsmap) that have
some issues.

    First, we are rapidly discovering that "suggesting" actual values for these
numbers may be a serious problem.  There is a process for early allocation
of code points managed by IANA.  It is a simple process, requiring only that
the draft co-authors request early allocation by the appropriate WG chair(s).
The WG chair will take it from there.

    It is my opinion that - until assigned - these code points may only be
referred to as "TBD."

    Second, the TLV type you have suggested is also suggested by another
draft (draft-ietf-mpls-return-path-specified-lsp-ping), but for a different purpose.

    This is precisely the reason why "suggesting" values is a problem for IANA
managed name spaces.

    Third, if you are defining a new TLV-Type from the name-space defined by
RFC 4379, you can (and probably should) use the numbers in sequence
(starting either with zero or one), in order to avoid confusing and/or fragmenting
the number space unnecessarily.

    You have chosen to start with the value 1, but have not indicated a specific
reason why zero should not be used.  In fact, you have stated that the valid
range is 0-65535.  You may want to either use the values 0, 1 and 2, or state
why zero is not used.

    Since you are in fact, defining a new TLV type, you do not need to request
IANA assignment of the sub-type numbers (since you have explicitly defined a
new name space for the TLV type).  You should simply make the assignment
of these initial TLV sub-types part of your definition of the new sub-registry.

    The WG chairs are working with the IESG to resolve this and related issues.
I believe it would be inappropriate to take any action on this information until
you are informed by the WG chairs as to what action to take.

--
Eric

[mpls] Issues with your use of TLV Type and sub-t… Eric Gray
[mpls] Issues with your use of TLV Type and sub-t… Eric Gray
Re: [mpls] Issues with your use of TLV Type and s… Loa Andersson