[v6ops] Operational Implications of IPv6 Packets with Extension Headers

[tom petch <[e-mail]>]

The problem that I have with this I-D is that I do not think that it will achieve its objectives.  It wants to raise awareness about the problems caused by Extension Headers so the target audience should be the world at large, especially those involved in setting up and operating IPv6 networks, but the style is, to me, rather academic, as if the audience was the sort of people who would be expected to be familiar with the literature and need little or no explanation.  I see this strongly in s.1, about Extension Headers, yet devoid of any reference, any explanation.  The first reference is RFC2460, which is Normative, so are readers expected to be familiar with the details therein?  One reaction might be 'So Extension Headers create problems so don't ever use them!'

The I-D lacks any explicit explanation of what an Extension Header is, what they were intended for, which bits have worked and which have failed so eg deprecating RHT0 is not very meaningful without some comment about RH something else.  Size matters as can be inferred from s.4 but there is no mention of the sizes involved of the IPv6 packet, with or without headers.  As I say, it seems that the reader is expected to know the literature.  There needs to be a page or two at the start giving the context within which the detail makes sense.

And then there is the future; should more Extension Headers be allocated, should they be constrained to avoid the difficulties raised here?  The I-D, for me, lacks an ending, lacks a look forward.

Tom Petch