Freebsd IP Forwarding performance (question, and some info) [7-stable, current, em, smp]

Ingo Flaschberger if at
Tue Jul 1 01:00:34 UTC 2008

Dear Alex,

>    >OK, I setup 2 boxes on either end of a RELENG_7 box from about May
>    >7th just now, to see with 2 boxes blasting across it how it would
>    >work.  *However*, this is with no firewall loaded and, I must enable
>    >ip fast forwarding. Without that enabled, the box just falls over.
> What is "ip fast forwarding" ?

instead of copying the while ip packet into system memory, only the ip 
header is copyied and then in a "fast" path determined if it could be fast 
if possible, a ned header is created at the other network-cards-buffer
and the ip-data is copied from network-card-buffer to network-card-buffer 

Kind regards,
    Ingo Flaschberger

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