Subject: RE: [Hipsec] SHIM6 adopting HIP packet format & small change to theformat

From: "Henderson, Thomas R" <[email-masked]>
Date: Thu, 13 Oct 2005 09:33:39 -0700

> 
> What do you think?  Are we willing to do these changes?
> 

I think this is a great opportunity for convergence.  I support aligning
HIP in this way, but I would like to know how stable the shim6 format is
at this time.

Tom

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From: Pekka Nikander <[email-masked]>
Date: Fri, 14 Oct 2005 12:01:44 +0200

> HIP in this way, but I would like to know how stable the shim6  

Impossible to say at this time.  We'll know better after Vancouver.
I have no idea how we are proceeding with the cross-area reviews.
The changes (swapping the place of the checksum and controls and
setting one reserved bit) are not that big, though.  IMHO, we might
take the risk, if needed.

--Pekka

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From: Petri Jokela <[email-masked]>
Date: Mon, 17 Oct 2005 11:29:18 +0300

> I have no idea how we are proceeding with the cross-area reviews.

The request for a review has been sent to people mentioned earlier on 
the mailing list. Unfortunately we have received only one - and negative 
- response.

> take the risk, if needed.

The checksum's place was selected so that it would be in the same 
location as UDP's checksum field. How possible it is that SHIM6 will 
change the checksum location in future drafts, maybe based on the same 
reason?

Otherwise, the change looks ok.

/petri

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From: Pekka Nikander <[email-masked]>
Date: Tue, 18 Oct 2005 11:22:15 +0200

> location as UDP's checksum field. How possible it is that SHIM6  
> will change the checksum location in future drafts, maybe based on  
> the same reason?

I don't think SHIM6 will bother with that, since the issue is there  
anyway with existing IPv4 UDP only.  From my point of view, it would  
be *nice* if we could use existing IPv4 UDP hardware to verify the  
checksum of the HIP header, but the potential ability to build hybrid  
shim6-HIP protocols is much more important.  Hence, my vote is to  
give up the checksum compatibility with existing IPv4 UDP.

--Pekka

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From: Gonzalo Camarillo <[email-masked]>
Date: Tue, 18 Oct 2005 14:50:25 +0300

Hi Pekka,

is your proposal to perform this change in the current draft of the main 
HIP specification?

Thanks,

Gonzalo

Pekka Nikander wrote:
>> change the checksum location in future drafts, maybe based on  the 
>> same reason?
> 
> 
> anyway with existing IPv4 UDP only.  From my point of view, it would  be 
> *nice* if we could use existing IPv4 UDP hardware to verify the  
> shim6-HIP protocols is much more important.  Hence, my vote is to  give 
> up the checksum compatibility with existing IPv4 UDP.
> 
> --Pekka
> 
> 

-- 
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From: Pekka Nikander <[email-masked]>
Date: Tue, 18 Oct 2005 14:29:15 +0200

Yes.  Plus the other small changes that I described in my previous  
mail, right fresh out from SHIM6 interim.

--Pekka

On Oct 18, 2005, at 13:50, Gonzalo Camarillo wrote:

> Hi Pekka,
>
> is your proposal to perform this change in the current draft of the  
> main HIP specification?
>
> Thanks,
>
> Gonzalo
>
> Pekka Nikander wrote:
>
>>> The checksum's place was selected so that it would be in the  
>>> same  location as UDP's checksum field. How possible it is that  
>>> SHIM6  will change the checksum location in future drafts, maybe  
>>> based on  the same reason?
>>>
>> I don't think SHIM6 will bother with that, since the issue is  
>> there  anyway with existing IPv4 UDP only.  From my point of view,  
>> it would  be *nice* if we could use existing IPv4 UDP hardware to  
>> verify the  checksum of the HIP header, but the potential ability  
>> to build hybrid  shim6-HIP protocols is much more important.   
>> Hence, my vote is to  give up the checksum compatibility with  
>> existing IPv4 UDP.
>> --Pekka

---

From: Erik Nordmark <[email-masked]>
Date: Thu, 20 Oct 2005 01:09:37 -0700

> up the checksum compatibility with existing IPv4 UDP.

FWIW *verifying* TCP/UDP checksums can be done independently of the 
location of the checksum field.

*generation* of the checksums on transmit does require the HW knowing 
(or being told) where the checksum result should go.

But both SHIM6 and HIP are control protocols, thus one wouldn't expect 
to see a large sustained stream of them.

   Erik