Re: I-D Action:draft-ietf-6man-exthdr-02.txt

[John Leslie <[e-mail]>]

Suresh Krishnan <[e-mail]> wrote:
> On 11-03-15 09:25 AM, John Leslie wrote:
>>>>
>>>> But I don't see the equivalent of Section 4.2 of RFC 2460, specifying
>>>> the TLV format.
>>> 
>>> The T is the "Next Header", the L is the "Hdr Ext Len" and V is the 
>>> "Header Specific Data" as specified in the figure in Section 4 of the
>>> draft.
>>
>> Well, of course "Next Header" _isn't_ the Type of this option (rather
>> it's the Type of the next option).
>>
>> And the "Hdr Ext Len" isn't a particularly intuitive coding of Length
>> either...
> 
> Yep. You are right on both counts, but I am not sure how we can change 
> this. We cannot chain the headers without the T being in the *previous* 
> header. I think the best we can do is to refrain from calling this TLV 
> like you said.

   That would satisfy me...

   But, the 2460 section 4.2 TLV also defines four actions when a Type
isn't recognized (skip and three cases of discard). exthdr-02 gives
us no way of defining skip-vs-discard.

   I think some mention of this issue would be wise. It appears, at
first blush, that you intend for a middlebox to skip over these
prospective extension headers, whereas 2460 calls for dropping the
packet.

   I'm not prepared to say what the resolution may be; I just think
it deserves some text (even if only to say, "Beware!").

--
John Leslie <[e-mail]>