Re: Slow TCP connection between linux and wince

Date: Fri Jun 02 2000 - 13:55:34 EST


> > > I've two computers (PC and philips velo 1) connected using null-modem
> > > cable at 115200. Unfortunately, connection speed is ~2.7K/sec (where
> > > 10K/sec should be possible). TCP dump looks like this:

Check again line. This tcpdump shows nothing abnormal, you should
see full line utilization.

In fact this tcpdump proves that this line is not 115kbaud. 8)
It is perfect to measure its real bandwidth. F.e. RTT is very
good estimated as 0.9sec.

> > The WinCE machine does not seem to implement delayed acks. Without that
> > good performance is very hard.

Failure to delaye acks do not affect throughput. Too long delay really can.
It is possible in this case, by the way. RTT does not match to link speed
even closely.

Window is small, but 2 packet window is also enough to saturate
this link.

To resume: either receiver holds ACKs (probably, it is confused
with its own small window), or something on link is wrong.
Incredible regularity of the tcpdump forces to suspect that it
is not 115kbaud really. 8)


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

This archive was generated by hypermail 2b29 : Wed Jun 07 2000 - 21:00:15 EST