Hi all,
in our community mesh network we recently discovered that a TP-Link
Archer C2600 device is unable to receive IPv6 UDP packets with a zero
checksum when RX checksum offloading is enabled. The device uses
ipq806x-gmac-dwmac for its ethernet ports.
According to https://tools.ietf.org/html/rfc2460#section-8.1 this sounds
like correct behavior as it says a UDP checksum must not be zero for
IPv6 packets. But this definition was relaxed in
https://tools.ietf.org/html/rfc6935#section-5 to allow zero checksums in
tunneling protocols like VXLAN where we discovered the problem.
Can the behavior of the stmmac driver be changed to meet RFC6935 or
would it be possible to make the (RX) Checksum Offloading Engine
configurable via a device tree property to disable it in environments
were it causes problems?
Best regards,
Julian Labus
