On 2012/03/28, at 1:42, Simon Perreault wrote:

> On 03/28/12 00:42, Tetsuya Murakami wrote:
>> Also, as I mentioned during the meeting, I double-checked the current
>> implementation of IPv6 stack (Linux/BSD). If implementing 4rd-u, IPv6
>> stack gives received IPv6 packet to 4rd-u module after processing it.
>> But, according to the current implementation of IPv6 stack, IPv6
>> stack totally removes IPv6 fragment header when IPv6 stack finds IPv6
>> fragment header and processes it.
>> 
>> Since 4rd-u module gets the packet after IPv6 stack processes the
>> packet, IPv6 fragment header is not present when 4rd-u module gets
>> the packet. 4rd-u utilizes IPv6 fragment header to carry some of IPv4
>> information. But all information embedded in IPv6 fragment header is
>> disappeared in IPv6 stack before 4rd-u module gets the packet. Hence,
>> in order to keep/pass the information embedded in IPv6 fragment
>> header to 4rd-u module, I think the existing IPv6 stack needs to be
>> changed.
> 
> Depends how you implement it. I can think of at least one way to do it on 
> Linux without touching the IPv6 stack. (with NF hooks)

Yes. It could be possible. But NAT44 requires a network device. If NAT44 is 
also utilized, a 4rd-u module attached to IPv6 stack similar to a tunnel/pseudo 
device is reasonable from the implementation point of view.

Thanks,
Tetsuya Murakami
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