How is bandwidth calculated?

[Terje K. <te...@kr...>]

From a quick test run on a linux box, using 1.7:

[terje@tzu terje]$ iperf -c 172.25.25.100 -u -t 5 -f b -b 5000k
------------------------------------------------------------
Client connecting to 172.25.25.100, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 65535 Byte (default)
------------------------------------------------------------
[  5] local 172.25.25.106 port 32781 connected with 172.25.25.100 port 5001
[ ID] Interval       Transfer     Bandwidth
[  5]  0.0- 5.0 sec  3128160 Bytes  5001318 bits/sec
[  5] Server Report:
[  5]  0.0- 5.0 sec  3107580 Bytes  4954921 bits/sec  3.454 ms   14/ 2128 (0.66%)
[  5] Sent 2128 datagrams

Looking at the figures, the client reports having transmitted
3128160 bytes. Apparently this is payload only, without 28 bytes
of UDP header. 3128160*8/5 = 5005056, which is close but not quite
correct. Is this due to timing issues?

However, on the wire data is transmitted with the headers, so it
should really be 2128 packets * 1498 bytes = 3187744, which becomes
3187744*8/5 = 5100390 bits/sec. Should there be an option to print the
data including headers? This concerns me, since I'm using iperf to test 
network hardware.

-- 
Terje Krogdahl

  "If it's a question of the network going down, we get helicopters, air 
   support, tanks - whatever we need," - Lieutenant Colonel Mims, Iraq