Re: [lwip-users] Help in getting maximum throughput with LWIP.

[David Empson]

Dany Thiffeault wrote:
> I found in the AVR32 datasheet this line:
> • Automatic Pad and CRC Generation on Transmitted Frames

That is referring to the padding (to a minimum length) of Ethernet frames, 
and the CRC which is appended to every Ethernet frame. (These are 
implemented in hardware on almost every platform.)

It is not the same thing as hardware support for TCP and UDP checksumming. 
These are normally handled at a higher level (in software), unless your 
Ethernet MAC has a special feature to automatically generate these checksums 
on transmit, and test them on receive.

The Ethernet frame CRC only protects the frame against errors when 
travelling over a local network segment. The TCP or UDP checksum allows for 
end-to-end verification of data in the packet, including possible corruption 
while the packet was held in memory of a switch or router, or some other bug 
which caused the data in the packet to be corrupted.