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Adaptive Bandwidth Control with Adjustable Threshold Disclosure Number: IPCOM000131685D
Original Publication Date: 2005-Nov-14
Included in the Prior Art Database: 2005-Nov-14
Document File: 3 page(s) / 64K

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Disclosed is a method for Adaptive Bandwidth Control that combines TCP-Nice [*] with an adjustable threshold. Also included is a method for determining and setting the appropriate threshold for a network.

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Adaptive Bandwidth Control with Adjustable Threshold

Method to determine the threshold (thresh) of a network in user-space:
1. Determine which network path you would like to test, and choose a target along that path.
2. Establish a network connection with the target, and capture packets leaving and arriving on that connection.
3. Send data to a target for at least 1 minute.
4. Keep track of the time from when a packet leaves the sender to when the "TCP Ack" is received from packet capture on the sender. This is called: usrtt.
5. Using this data - graph the usrtt vs. time. (See examples below).
6. Determine the time at which a large percent (ex. 90%) of the usrtt's appear below this line. This is the thresh expressed in round trip time.
7. Convert thresh in round trip time so that it is a fraction from minRTT to maxRTT (example 90% of packets are below the line that is 10% of the way from minRTT to maxRTT - then threshold is equal to 10%).

The test should be run along different network paths from the sender to receivers. So - if the sender manages receivers in both Los Angeles and New York then one target in each location should be tested.

The test should also be run under different network conditions, such as during business hours and in the middle of the night.

Based on how "adaptive" you would like the sender to be, you should pick the value for threshold that is the largest. For example a threshold of 10% may be okay for LAN endpoints but if VPN targets require 30%, then using 30% for all connections will give slower but more adaptive distributions.

Finally, change the value of thresh in the TCP-Nice algorithm using the value determined above. The configurable thresh should be available to end users without recompiling the TCP-Nice code.

Example, Threshold configured too lo...