On Apr 26, 2010, at 9:07 PM, Jukka Manner wrote:

> Hi Lloyd,
> 
> I have to object here. :)
> 
> On 22.4.2010 13:50, [email protected] wrote:
> 
>> The GUT draft and recreating IP packets strikes me as problematic in 
>> implementation, just as much as NATs. I'd rather have a simple 
>> IP-in-IP-tunnel (or even GRE) and rely on decap at the endpoints...
>> 
> 
> GUT is not problematic, nor difficult. We have it running on Linux and works 
> great. Next we'll put it on BSD (should be just a medium update to the code). 
> I'm hoping to release the implementation as open source sometime in the 
> future.
Hi Jukka,

please note that the encapsulation/decapsulation part for SCTP is simple. 
However,
if you want to do the encapsulation because you want to traverse NAT which are
not supporting SCTP, you also must avoid all transport addresses inside the SCTP
layer. This needs to be described somewhere and is specific to SCTP. It might
be able to generalize it to transports which support multihoming.

Also, if you cover the handling of ICMP messages, you must provide some protocol
specific packet validation, I think. For example, in case of SCTP, you need to
validate the verification tag before processing the packet inside the SCTP 
stack.

Best regards
Michael
> 
> Our draft could be much better in explaining the idea clearly. The fact that 
> we are "creating ip packets" is due to our implementation being a separate 
> piece of code, a separate service on the OS, easily installed. The 
> functionality could be as well be integrated into the IP stack, but that 
> would be somewhat more challenging.
> 
> regards,
> Jukka
> 

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