VZ FIOS and Intel TCP IPv6 Checksum Offload problems

Sean Donelan sean at donelan.com
Mon Aug 29 15:59:58 UTC 2022

On Sat, 27 Aug 2022, Michael Thomas wrote:
>> In some situations where a client machine is connected via some specific 
>> Optical Network Terminals (ONTs), and data is appended after the packet 
>> checksum, the network adapter can drop receive packets when using TCP-IPv6 
>> Checksum Offload for receive traffic.
> My reaction is "offload from what"? Isn't this all done in silicon?

Because the interoperability flaw is in silicon, it can't be easily fixed 
in either the legacy wired Intel ethernet controller or fiber ONT.  Would 
need to replace the hardware to fix the silicon.

Need to disable the hardware IPv6 TCP checksum offload, so its not mangled 
or dropped at the silicon layers anymore.

Its annoyingly intermittent and not visible with client-based Wireshark 
because the corruption occurs in the hardware controller.

More information about the NANOG mailing list