Re: Proposed new pcap format

[Guy Harris <guy () alum mit edu>]

On Tue, Apr 20, 2004 at 06:16:48PM -0700, Michael Richardson wrote:
>     Darren> btw, is it at all easily possible to get the 802.3 checksum
>     Darren> into captured data ?
>  
>   On some OSes you ask for that. Not on BSD AFAIK, yes, with PF_PACKET
> on Linux.

Some BSDs give it to you, at least for some interfaces, with no way of
not getting it (OS X with the Apple 10/100/1000 interfaces, and I think
at least some NetBSD drivers do).

How do you ask for it on Linux?  (Or are they like those BSDs in that
regard?)

>   And with GbE encoding, ECC memory and parity protected L3 cache buses,
> the PCI bus *is* the least reliable interface in a typical PC. I believe
> that people who do TCP checksum offload have experienced this problem
> already. 

"Everything old is new again."  We had a similar problem with an
EISA-bus network device at Network Appliance ages ago - we didn't turn
UDP checksumming on by default, and that problem caused us to do so, and
the checksum caught the problem.
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