On Mon, Jan 28, 2019 at 07:20:10PM +0000, Shah, Ashwin (Nokia - US/Sunnyvale)
wrote:
> The change conforms to Annex E.1 (IPV6) of the IEEE spec.
Oh really?
A transmitting node shall extend the UDP payload of all PTP
messages by two octets beyond the end of the PTP message. The
contents of the UDP checksum field or the final two octets of the
UDP payload may be modified by the initiator or an intermediate
node to ensure that the UDP checksum remains uncompromised after
any modification of PTP fields.
TWO bytes, not four, are allowed.
> Included is an explanation from Qulsar on why are they adding the additional
> bytes to the UDP payload.
> https://qulsar.helpscoutdocs.com/article/74-why-are-there-4-bytes-after-the-ptp-message
After reading that, kind words fail me, so I should probably say
nothing at all. The last paragraph is downright insulting.
In any case, there are plenty of other one-step implementations that
update the UDPv4 checksum in place. It isn't rocket science.
Long ago I decided not to let this project's software become a
showcase of workarounds for various random hardware bugs.
Sorry,
Richard
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