When will the TCP checksum go bad?

  • Thread starter Thread starter zhou.honglin
  • Start date Start date
Probably your NIC is calculating the checksums instead of the CPU.
You can change this in the NIC-driver configuration.

/D
 
Can u tell me how to config it?
Sorry but I only know using NIC to calculate checksum can reduce the
load of CPU...
David D 写é“：
 
You really don't have to configure anything. The packet checksums are ok when on the network.
It's just Ethereal captures it before the NIC has done it's job.
You can change Ethereal to not validate the checksums... in Edit/Preferences/Protocols/IP - uncheck "Validate the IP checksums if possible".

If you really, really want to change the NIC config you open "Network Connections"
right-click on the connection, open "preferences", and click "configure".
In the "Advanced" tab there would be some "IP checksum offloading"-properties.
Set them to OFF, especially the one for sending.
The properties varies between NIC drivers so maybe their name is different or they are missing.
My NIC is a Intel Pro/1000MT ant I have 4 of theses ( IP and TCP, send and receive).

/D

ps I run a Swedish WinXP so the properties and other might not be correctly translated, hope you get the point anyway.
 
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