Subject: [Fwd: Re: [rohc] IPv6 deployment in profile 2 and 4]

From: Ana Carolina Minaburo <[email-masked]>
Date: Tue, 30 Jul 2002 10:35:54 +0200

hi!

We are interesting in the compression of IPv6 header, and analising your 
draft we found some problems using it with IPv6.

Perhaps your proposition is correct for IPv4 but it needs something more 
simple for IPv6.
As IP-Id is not in the original header, new format packets for IPv6 can 
be proposed?

Another porblem we found, but perhaps you have the solution is: in the 
transition modes is that the IR, IR-Dyn and UOR-2 do not contains the 
mode in which the compressor is working, only when you send UOR-2 with 
extension 3 then the transition is finish, in our implementation, the 
transition is blocked until an UOR-2+ext3 arrives!  In profile 1, the 
mode is added in  the original RTP header, then it is send in IR, 
IR-DYN, UOR-2 packets, then as in profile 4 there is not RTP then the 
mode is not added.

Ana

Lars-Erik Jonsson (EAB) wrote:

>>>First an important note. Profile 4 has not yet been defined, there 
>>>is a proposal available but that does not mean the profile will look
>>>that way when it is finalized.
>>>
>>Ok, as in your draft description profile 4 seams to be similar to 
>>profile 2, then normally you use the same packets types with the same 
>>fields.
>>
>
>Yes, the intention with the current draft was to make the profile 
>totally in line with profile 2. However, as we discussed in Yokohama, 
>we might want to make profile 4 much more simplified. That is an issue
>for further discussion.
>
>
>>>Anyway, back to the original question. If a format is used for IPv6,
>>>which has an IP ID field, that could be set to any value since it 
>>>would not be used by the decompressor.
>>>
>>Ok, but perhaps it is better do not send it. Perhaps I am 
>>wrong but if it is not needed is better do not send it.
>>
>
>We should be clear with what we are discussing here. In general, 
>of course it is a waste of bits to send unnecessary information.
>However, it might be motivated with common formats, which was
>the case here. Further, we do not have a choice for profile 2, 
>since there we already have standardized the formats as they are
>now written. We do have an option to do different for the
>future profile 4, so in that context the discussion might be
>motivated.
>
>
>Cheers,
>/L-E
>
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