VZ FIOS and Intel TCP IPv6 Checksum Offload problems

Michael Thomas mike at mtcc.com
Sat Aug 27 22:07:12 UTC 2022

On 8/27/22 12:00 PM, Sean Donelan wrote:
> Hopefully, my pain will help someone else.
> I've had sporadic Internet slowdowns and stuck networking since IPv6 
> was enabled on my FIOS ONT a few months ago.
> After too much troubleshooting, I found out some older Intel GbE 
> ethernet cards have a IPv6 Checksum Offload incompatibility with 
> certain fiber ONT terminals.  As Verizon is enabling IPv6 on its FIOS 
> network, you might find intermittent network problems.
> Intermittent are the worst kind of problems.
> 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.
> Intel published an alert in 2017, but I didn't have IPv6 on FIOS then.
> https://www.intel.com/content/www/us/en/download/19174/disabling-tcp-ipv6-checksum-offload-capability-with-intel-1-10-gbe-controllers.html 
> TLDR; turn off TCP IPv6 Checksum Offload
> Affects all operating systems (Windows, BSD, Linux, etc) using the 
> affected wired Intel ethernet controllers.  Not a problem with Intel 
> WiFi.

My reaction is "offload from what"? Isn't this all done in silicon?


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