Hello,
> -- slow start sequences
You can recognize slow start sequences by looking at the middle line
of the time sequence graph, i.e. the transmitted segments. Especially
in the beginning, they should be forming a somewhat exponential line,
that is transmitting first one segment at a time, then two, then 4,
then 8, and so on. It doesn't quite come out to be that way, but
somewhat along those lines. Cf.
http://colmar.informatik.uni-tuebingen.de/uwe/10-10-slow.png
(For the archive: The links are not to stay, and will expire fairly
soon.)
> -- retransmission triggered by duplicate acks,
Retransmissions should occur after more than 3 duplicate acks.
Generally, and fairly simply speaking, you can recognize
retransmissions by watching for segments (the middle line), which get
transmitted again. Cf.
http://colmar.informatik.uni-tuebingen.de/uwe/retrans.png for
retransmissions at second 21 through 26.
> -- regions where the sliding window is limiting transmission
After the congestion in the picture mentioned above, the sliding
window is limited by a newly set cwnd value. There you can see the
cwnd limiting the amount of segments transmitted, and not the raw.
> -- lost acks
Don't know. I'd think you cannot read them from the graph, since they
are lost. We would never know, or see them, since at some point they
will get resent.
> -- understand the segment and ack numbers
?! They can be read from the y-Axis.
> -- congestion and sliding window sizes
The picture under
http://colmar.informatik.uni-tuebingen.de/uwe/retrans.png is the
result of a congestion (pingflood on a low memory router.) I interpret
the sliding window to be the distance between the acks (the lower
line) and the minimum of cwnd and ssthreshold. In general, the sliding
window is the distance between the acks and the transmitted segments.
>
>
> I was also wondering if it would be possible to change the
> axis scaling of
> graphs and if I could save the generated graph in some format?
You can zoom in by using the center button, zoom out by using shift
and center button. The graph can be moved by klicking and dragging
with the right mouse button.
Scaling can probably be changed also with the graph dialog box, but I
never use it.
Hope this helped a bit.
Uwe
