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Re: 4rd-U informal meeting - Tuesday 15:15 Room 204

by Maoke Chen :: Rate this Message:

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2012/3/28 Simon Perreault <simon.perreault@...>
On 03/28/12 09:22, Tetsuya Murakami wrote:
In terms of CNP, CNP needs to be calculated every time if the packet
is toward to outside of domain because the embedded IPv4 address
could be different. So, I think there is no difference between CNP
and recalculation of L4 checksum from the implementation point of
view.

On the contrary, there is a big difference. The difference is that you are only concerned with L3. L4 can change: UDP, TCP, ICMP, STCP, DCCP, etc, etc, etc. You need a lot of code to handle all existing transport protocols, and you still can't handle future protocols that people might develop.

misunderstanding on ICMP. 
1. ICMP is not transport protocol. 
2. ICMP cannot benefit from CNP at all because ICMPv4 checksum doesn't cover the pseudo-header while ICMPv6 does. 

just FYI. 

- maoke
 

Checksum neutrality is a *big* advantage.


Simon
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