Re: Netboot E250 -- tftp problem (SOLVED)
On Wed, Jan 23, 2008 at 10:07:15PM +0800, Hero_xbd!.RRR wrote:
> 2. There was a lot of UDP checksum errors in TFTP packets annoying us
> badly. But they are really irrelevant: before I got to the solution, I
> replaced Realtek 8139 NIC with Intel e100, and the checksum errors had
> all gone, but it still get stuck with packet. After I succeeded with
> Intel e100, I changed back to Realtek 8139, the checksum errors emerged
> again, but E250 still netbooted.
> I don't know whether it is a bug with wireshark or a flaw with Realtek 8139.
It's neither. If your capturing on the host sending out the packets, you'll
only see what packets look like when linux sends them to the network card, not
what's actually going onto the wire. If the checksumming is offloaded to the
network card, then the linux won't put a valid checksum in, as the nic will do
that before sending it out onto the wire anyway.
So your e100 apparently doesn't do hw checksumming, while the 8139 does.
Causing wireshark to detect invalid checksums with the 8139, but not with the
e100.
It's a quite common cause for confusing, but as long the checksum errors are
for packets send out by the capturing machine you can (and should) just ignore
them.
Sjoerd
--
The moon is a planet just like the Earth, only it is even deader.
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