wierd dsl performance with -CURRENT

Kenneth Culver culverk at yumyumyum.org
Wed Jul 9 19:56:30 PDT 2003

> In the last episode (Jul 09), Kenneth Culver said:
> > > look of any large values in the timestamps and see if there is
> > > anything before that indicates a lost packet or a re-ordered one or
> > > something (or a retransmitted ack)
> > >
> > > The key is to find the gap in the arriving packets and figure out
> > > what caused it..
> > >
> > Alright, I'll have to do this later this evening, don't have time
> > right now. Thanks for the help though.
> Tcptrace is great for this; the tsg output graph will mark out-of-order
> packets and duplicate acks for you.
Alright, I used this and got a bunch of xpl graphs, but I'm not really
sure what I'm looking at or for. The only graph I really understand is the
d2c_tput.xpl, which is the thruput of the ftp data connection from
ftp2.freebsd.org to my machine. I have posted the xpl's, along with the
binary tcpdump output used to create the graphs. I've also posted the
ascii output of the same download. All of these are posted at

the graphs are *.xpl, the binary output is tcpdump.out, and the ascii is




Commands used:

for tcpdump:


tcpdump -ttt -w tcpdump.out host kenshin


tcpdump -ttt host kenshin | & tee tcpdump.ascii

and to create graphs:

tcptrace -GC tcpdump.out

And the output of tcptrace:

1 arg remaining, starting with 'tcpdump.out'
Ostermann's tcptrace -- version 6.3.2 -- Mon Oct 14, 2002

1756 packets seen, 1756 TCP packets traced
elapsed wallclock time: 0:00:00.203206, 8641 pkts/sec analyzed
trace file elapsed time: 0:00:09.670714
TCP connection info:
  1: kenshin:49178 - ftp2.freebsd.org:21 (a2b)       9>    8<
  2: kenshin:49179 - ftp2.freebsd.org:58751 (c2d)  717> 1022<  (complete)

All the xpl and output files are at the site listed above.

Thanks again

More information about the freebsd-current mailing list