On 16 Nov 2010, at 18:53 , Hing-Kam (Kam) Lam wrote:
> On Tue, Nov 16, 2010 at 12:32 AM, RJ Atkinson <rja.li...@gmail.com> wrote:
>> Standardising this proposal has the effect of breaking
>> this *deployed* capability, which is important to a
>> significant installed base that use this capability today.
>
> Standardising any new protocol number will break this deployed box.
No.
Only adding new non-terminal protocols with distinct Protocol
numbers could break the deployed systems. Having the IETF TSV
Area define, for example, a new transport protocol does not break
the deployed systems.
> How will this box be able to parse a new extension header that is
> introduced when it does not understand this.
Protocol numbers can be assigned by IANA in response to a request
from nearly any WG in any IETF Area, and usually are not even
IPv6-specific.
This draft would only apply to a new IPv6-specific Protocol
number assignment, so it can not solve the problem you describe.
>> We do not want to encourage the creation of ANY IPv6 option
>> that is NEITHER a Destination Option NOR a Hop-by-Hop option
>> and consequently are NOT carried inside either of those headers.
>
> The draft does not do that. I dont know which version you have been
> reading.
It does encourage development of such IPv6 optional headers --
simply by saying this is how one specifies new IPv6 header types.
RFC-2460 says that new optional headers ought NOT be created
except under very carefully defined narrow circumstances
(RFC-2460 Section 4.6, but read my text below first :-).
This draft's language is not fully aligned with RFC-2460
at present.
At a bare minimum, this draft needs editing to be fully aligned
with RFC-2460, including new text to say explicitly that:
"Any new IPv6 extension MUST use either the existing
IPv6 Destination Options Header or the existing IPv6
Hop-by-Hop Options Header if the new extension has
either end-to-end or hop-by-hop properties."
Note also that the paragraph I've written above is only slightly
stronger than what RFC-2460 already says about creating new
optional headers (see Section 4.6, specifically the bottom
of Page 23 and the top of Page 24 in RFC-2460).
Yours,
Ran
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