The User Goodput view captures the client experience. It shows the number of good bytes transmitted (minus retransmissions) divided by the amount of time required to transmit this information.
When you download data from the Web, the browser typically computes the throughput for you as you download the file. Throughput is the number of bytes transferred divided by the period of activity. Typically, you would use this throughput value to gauge the effectiveness of your network connection and view the calculated User Goodput by subtracting retransmitted bytes from the throughput because retransmitted bytes artificially inflate throughput.
If you have a throughput measurement of 100 kbps, but half of the download consists of retransmissions, the User Goodput is 50 kbps; therefore, you benefit from only half of the throughput.
User Goodput and Throughput are computed only during periods of active transmission. The monitoring device averages the Traffic Rate over 5-minute intervals. Much of that time could be silent. There is little relationship between User Goodput/Throughput and Traffic Rate.
To illustrate this point, consider the following scenario. If the only transfer during a 5-minute interval is a 50 KB document downloaded without retransmissions in 1 second, these metrics apply:
50 KB * (8 bits/byte)/1 second = 400 kbps
50 KB * (8 bits/byte)/300 second = 1.3 kbps
User Goodput is useful only if there is significant data transfer and is used for bulk transfers, not interactive transactions. Throughput is computed using the same formula as User Goodput (bytes divided by Data Transfer Time) except that it includes retransmitted packets. Throughput is always greater than or equal to User Goodput.
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Look for |
Might Indicate |
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Dips in User Goodput |
Network congestion. Use User Goodput as a network metric only when there is traffic being transferred. few bytes, whether transmitted slowly or quickly, might not be useful. |
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Poor Goodput |
Data Transfer Time is hampered by poor server or application performance. |
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