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The I/O graph appears to let you visually graph throughput, yet there's the TCPStream Throughput graph. The throughput measured between the two graphs seem to be way off just comparing Bytes/sec. I'm not sure how either is derived, so I need some input on this.

Which is the more accurate representation of actual data throughput?

asked 28 Sep '12, 09:51

CarlT's gravatar image

accept rate: 0%

They are both accurate, but they're displaying different things by default.

Unless you apply a display filter, the I/O graph will show you the throughput of all traffic in the trace file, in both directions. The TCP Stream Throughput graph will show only the throughput from one TCP stream, in one direction, based on the selected packet. If you filter the I/O graph so that it is looking at the same traffic as the Throughput graph, you'll see the same values for Bytes/sec.

To verify:

Select a TCP packet traveling in the direction of data flow. Note the source IP address, then expand the TCP portion of the packet and note the stream index number. With this packet still selected, view the TCP Stream Throughput graph.

Now open the I/O graph (leave the Throughput graph open for comparison). Under 'X-axis' leave the 'Tick interval' at 1 second. Under 'Y-axis' change 'Units' to 'Bytes/Tick' and then apply the following filter to the Graph 1 field: && ip.src==a.b.c.d

For 'n' substitute the TCP stream index number and for a.b.c.d substitute the source IP address. Click the Graph 1 button once to turn it off, then click it again to turn it back on, which will activate the filter that you entered.

Now arrange the I/O graph and the Throughput graph side-by-side on your screen. The two graphs are now looking at the same data and you should see that the values in the two graphs correspond very closely.

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answered 29 Sep '12, 22:43

Jim%20Aragon's gravatar image

Jim Aragon
accept rate: 24%

edited 29 Sep '12, 23:56

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question asked: 28 Sep '12, 09:51

question was seen: 19,415 times

last updated: 29 Sep '12, 23:56

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