Subject: Re: 6MAN WG Last Call: <draft-ietf-6man-exthdr-03.txt>

From: David Malone <[email-masked]>
Date: Fri, 1 Jul 2011 10:49:42 +0100

I was a little surprised by this document when I read it. The title
is "An uniform format for IPv6 extension headers", and the abstract
reads as I'd expect. However, when we get to section 3 (Applicability)
"SHOULD" and "MUST" are used, *not* to require people to use a uniform
format for IPv6 extension headers, but instead:

	1) implementations SHOULD use destination options as the
	preferred mechanism for encoding optional destination
	information

	2) The request for creation of a new IPv6 extension header
	MUST be accompanied by an specific explanation of why
	destination options could not be used

	3) new IPv6 Extension Header(s) having hop-by-hop behaviour
	MUST NOT be created or specified

	4) new options for the existing Hop-by-Hop Header SHOULD
	NOT be created or specified unless no alternative is feasible

	5) new optional information to be sent SHOULD be encoded
	in a new option for the existing IPv6 Destination Options
	Header

	6) new IPv6 extension headers MUST NOT be created or
	specified, unless no existing IPv6 Extension Header can be
	used

	7) Any proposal to create or specify a new IPv6 Extension
	Header MUST include a detailed technical explanation of why
	no existing IPv6 Extension Header can be used

I don't particularly object to any of these, but none of these
relate to the format of IPv6 extension headers. When we get to
section 4, which details the uniform format, no SHOULD or MUST
language is present.

This seems to mean that the document's title and abstract do not
match the imperative content of the document. Fixing this could be
a simple as changing the title and abstract, plus possibly adding
something in Section 4 to actually encourage use of the uniform
format.

I've also noted a few more minor points below.

	David.

Title: "An Uniform" - for me this should be "A Uniform". Googling
for both says "A Uniform" is more used by about 40-1, but also
brings up some documents explaining the disagreement.

Section 1: "Also, Several" -> "Also, several"

Section 3: I think there's an unwanted page break after the first
paragraph of section 3.

Section 4: Should you give a reference to the IANA protocol numbers
registery when you desceibe Next Header?

Section 5 should probably give a list of the existing headers that
do follow this format.