Messages in this thread | | | Date | Fri, 4 Jun 1999 14:31:01 +0200 | From | Jamie Lokier <> | Subject | Re: zero-copy TCP fileserving |
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Richard B. Johnson wrote: > It looks as though the normal CRC is appended during the actual transmit. > If the offset of the checksum was known to a controller, it could fill in > the checksum using the same mechanism.
The difference is the Ethernet CRC goes at the end of the frame (designed for insertion by hardware), but the TCP/UDP data checksums go _before_ the data.
So hardware has to buffer an entire frame before it can insert the TCP/UDP checksum. As most (if not all) network drivers do load the entire frame onto the card before beginning transmission, this is a possibility.
-- Jamie
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