A question for NDIS 5.1 Checksum offload

NTDEV
1

Hi everyone

I’m playing the checksum offload on NDIS 5.1.
I’ve confirmed the flags NdisPacketChecksumV4 and NdisPacketTcpChecksum in NDIS_TCP_IP_CHECKSUM_PACKET_INFO are both set to 1.
Why the TCP checksum field is not zero in the send packet?
According to the document, it should be zero, doesn’t it?

– Pingwei

2

Humm…

The WDK documentation for this says:

“Before offloading the checksum calculation for a TCP packet, the TCP/IP
transport calculates the one’s complement sum for the TCP pseudoheader.”

Thomas F. Divine
http://www.pcausa.com

From:
Sent: Thursday, November 11, 2010 9:10 AM
To: “Windows System Software Devs Interest List”
Subject: [ntdev] A question for NDIS 5.1 Checksum offload

> Hi everyone
>
> I’m playing the checksum offload on NDIS 5.1.
> I’ve confirmed the flags NdisPacketChecksumV4 and NdisPacketTcpChecksum in
> NDIS_TCP_IP_CHECKSUM_PACKET_INFO are both set to 1.
> Why the TCP checksum field is not zero in the send packet?
> According to the document, it should be zero, doesn’t it?
>
> – Pingwei
>
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