On 23 May, Bill Paul wrote: >> > >> > Just to let people know, I have been trying to investigate this, but >> > my time has been somewhat limited lately. The original reason I turned >> > off the IP checksumming on transmit was that there was one test case >> > where the chip seemed to be generating improper checksums. That is, >> > if you did something like: ping -s 1473 <otherhost>. This would result >> > in a full sized frame, plus a small IP fragment containing just one >> > byte of data. On the machine I used for testing, the small fragment >> > was rejected by the host on the other side due to a bad header checksum. >> >> According to the second note in the Intel document that I cited, >> hardware checksumming is unsupported in this case. > > Argh. No. IP checksumming == a checksum of the IP header only. The > chip is perfectly capable of computing IP header checksums over > fragments, and does so quite well, _except_ in this one bizarro case > I encountered with tiny packets on this single P166 system. Maybe that was the original intent and hardware bugs were found later. The Intel document specifically says (emphasis mine): Therefore, the driver should not request *any* offload features for an IP fragment.Received on Fri May 23 2003 - 11:35:28 UTC
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