in case of resetting the t_dupacks in tcp_input.c

[조용민]

Hi,

I have a question that reset a dupack count in tcp stack.
My company's product was tested on freebsd 10.
As far as I know The fast retransmission is triggered when the receiver is
received 3 dup acks.
Why is the t_dupack value reset, if we happen to get data or a window
update along with a duplication ack?

I checked openbsd and netbsd.
The t_dupack is not reset on the netbsd, if it receive ack that
get a window update(changed) along with a duplication ack.
The t_dupack is reset on the openbsd, if it receive ack that
get a window shrink along with a duplication ack.
I don't know why the t_dupack is reset, if to get a window update.
I think Just it is skipped(is not reset),
if we receive the ack that is window update. like netbsd.

could you explain about this?

Thank you in advance for your answers!

Best Regards,
Yongmin