> On May 16, 2016, at 8:21 AM, Tal Mizrahi <[email protected]> wrote:
> 
> Hi Ole,
> 
> Thanks for the prompt response. 
> 
> It would be helpful if the authors added a comment about the L4 Checksum to 
> the current draft, even though this functionality was defined in RFC 2460.


please read carefully draft-ietf-6man-segment-routing-header.

The model described assumes encapsulation of the original packet into an outer 
ipv6 header followed by a SRH. When the packet leaves the SR tunnel there are 
no traces of segment routing whatsoever. L4 clearly does not apply here, it’s 
basic tunneling.

s.


> 
> Best regards,
> Tal.
> 
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]]
>> Sent: Sunday, May 15, 2016 9:07 PM
>> To: Tal Mizrahi
>> Cc: [email protected]; [email protected];
>> 6man WG
>> Subject: Re: [spring] L4 Checksum and draft-ietf-6man-segment-routing-
>> header
>> 
>> Tal,
>> 
>>> [Apologies if this issue has been discussed before.]
>>> 
>>> According to draft-ietf-6man-segment-routing-header, an ‘SR Segment
>> Endpoint Node’ updates the Destination IP address.
>>> Therefore, it must also update the Layer 4 Checksum, right?
>>> 
>>> I wonder if there is an upper bound on the size of the SRH. Otherwise, the 
>>> L4
>> Checksum may be located in a pretty deep location.
>>> Speaking from a chip vendor’s perspective this may be a problem.
>> 
>> From RFC2460, RH0:
>> 
>> 
>>     o  If the IPv6 packet contains a Routing header, the Destination
>>        Address used in the pseudo-header is that of the final
>>        destination.  At the originating node, that address will be in
>>        the last element of the Routing header; at the recipient(s),
>>        that address will be in the Destination Address field of the
>>        IPv6 header.
>> 
>> I would expect SR would work the same.
>> 
>> Cheers,
>> Ole
> 

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