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

From: Eric Gray <[email-masked]>
Date: Thu, 28 Oct 2010 03:14:43 -0400

Mach/So,

    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 (17,
18 and 19) in your draft (draft-ietf-mpls-return-path-specified-lsp-ping) that
have some issues.

    First, we are rapidly discovering that "suggesting" actual values for these
numbers is 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-lsp-ping-enhanced-dsmap), 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.

    If you are in fact, defining a new TLV type, you should not need to request
IANA assignment of the sub-type numbers (since you will be defining a new
name space for the TLV type).

    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.

    I think that you also made a small typographical error in section 6.3, where
I believe you have "TVL" instead of "TLV"...

--
Eric