[P4-dev] Incremental checksum with v1model?

Tom Barbette barbette at kth.se
Sun Feb 16 03:48:30 EST 2020

Hi Andy,

Thanks I'll try that and report back ;)


Le 14/02/2020 à 19:20, Andy Fingerhut a écrit :
> I do not have source code to point you at, but the PSA specification has 
> some sample P4-like pseudocode for the implementation of the 
> InternetChecksum extern that should be correct (I won't bet $1000 on it, 
> but I will bet $100 on it :-).  Look here:
> https://p4.org/p4-spec/docs/PSA-v1.1.0.html#appendix-internetchecksum-implementation
> I did some very careful reading of RFCs related to the Internet checksum 
> involving prior bugs in older RFCs specifying how it was specified 
> incorrectly in earlier versions, and tried hard to follow them, and used 
> some formal proof techniques for small cases that looked promising that 
> it should be correct.
> Andy
> On Fri, Feb 14, 2020 at 6:43 AM Tom Barbette <barbette at kth.se 
> <mailto:barbette at kth.se>> wrote:
>     Hi all,
>     Does anyone have an example of incremental checksum correction (in my
>     case for TCP) in P4 with the v1model? I know PSA has the
>     InternetChecksum.substract, but I'd like to run it with v1.
>     I tried a few common tricks, but I have a one compilment's bug from
>     time
>     to time.
>     Thanks,
>     Tom
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