>>
>>I am not sure why Windows kernel doesn't compute UDP checksum for all
>>tunnels. I added Nithin to the thread to see if he has some idea. My
>>wild guess is that it tries to save some computational workload.
>
>My guess is that it is because VXLAN originally specified that
>checksums should not be used. However, my expectation is the checksums
>will be more common with Geneve and in all cases the request of
>userspace should be honored. It also seemed like GRE was allocating
>space for the checksum but not actually computing/verifying it, which
>is odd. However, it's definitely possible that I'm missing something.

Yes indeed. For VXLAN, UDP checksum was optional and we got by without
calculating it. We seem to be parsing the OVS_TUNNEL_KEY_ATTR_CSUM
attribute. So, might as well add the code to request NDIS to calculate UDP
checksum if OVS_TNL_F_CSUM is set.

For GRE, you are right Jesse. Looks like we are punting on calculating
checksum even though we reserved space for it. On the sending side there¹s
no validation either so, that make Hyper-V to Hyper-V case work. KVM to
Hyper-V interop would probably fail.

-- Nithin

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