A tool to measure the round-trip time and bandwidth of a TCP connection with different methods. Bandwidth (or more precisely Goodput) is measured with the harmonic mean. rtt is measured via weighed moving average.
Currently tcp-metrics only supports resources that are available via HTTP/1.1. The reason for this is that most static resources are available via HTTP and it is easy to deploy a static testing resource on a HTTP server.
Two methods are available to measure the Goodput:
1.: by using the first socket.read() timestamp as the start time.
2.: by using a later subsequent socket.read() timestamp as the start time (to avoid bursts and slow-start falsifying the estimate).
For detailed information concerning the techniques applied please check out http://fishi.devtail.com/weblog/8/
Usage: tcp-metrics [OPTION...] DOMAIN PATH
Example: tcp-metrics yourdomain.com /your/resource
-a, --all Measure everything - option1 + option2 + rtt.
-b, --bandwidth-method-A Measure the bandwidth with option 1, meaning the
first socket.read() operations are skipped in
order to avoid initial bursts and TCP slow-start
to falsify the result.
-c, --bandwidth-method-B Measure the bandwidth with option 2, meaning we
measure beginning from the first socket.read()
operation.
-k, --skips=Skips Number of socket.read() Skips to avoid bursting
and TCP slow-start to falsify the result - by
default this value is 10. Note that a value of 0
here would be the same as using measurement option
2 (-c).
-m, --multi If set, for each round a different TCP socket is
used. That way you might get a better overall
estimate about an expected path between the client
and the resource. Please note, that you need at
least two measurement rounds for this option,
since otherwise you will only use one TCP socket
anyways...
-n, --rounds=Rounds Number of repeated measurement Rounds. In order
to get a fair estimate of the rtt, several rounds
should be used. By default this value is 1.
-p, --port=Port The Port the resource to measure is available at
- default is 80.
-r, --rtt Measure the rtt.
-s, --size=Size Size of the receiver buffer - if not specified,
by default a 2MB receiver buffer is used. Note
that on each socket.read() the buffer is written
from the start (it is just a dummy buffer...).
Please note, that if this buffer is to small, the
socket.read() operation does not have enough
memory to store data to - thus a huge bottleneck
in the application layer would occur.
-t, --timeout=Timeout The socket Timeout in seconds - by default 2s.
-v, --v Verbose - print subsequent estimates to stdout.
-?, --help Give this help list
--usage Give a short usage message
-V, --version Print program version
Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.