Hello,
While going through the following piece of code in
linux/include/net/tcp.h in linux kernel 2.4.2:
In function : tcp_initial_window(...) on line 1520
if (mss > (1<<*rcv_wscale)) {
int init_cwnd = 4;
if (mss > 1460*3)
init_cwnd = 2;
else if (mss > 1460)
init_cwnd = 3;
if (*rcv_wnd > init_cwnd*mss)
*rcv_wnd = init_cwnd*mss;
}
It seems to me that if the mss is 1460 , then unless the rcv_scale
is 11, the rcv_wnd will always be 4*mss .
I think this is the reason that I am always observing 5840 ( 4*1460 )
in <SYN> packets orignating from machine.
Even when I try to increase SO_RCVBUF using setsockopt, initial
window doesnot change.
Is there any specific reason for keeping initial window value fixed ?
Manish
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