Connection Analysis
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SQRT01: Retransmit Timeouts greater than 0
Consider this real life example. Imagine having a telephone conversation where the line is crystal clear. In such a call it is unlikely that you will have the need to repeat anything you say. Now imagine a bad connection like a poor cell phone call where you ask a question but due to the poor quality you do not hear the answer. In such a call you will wait a short while (timeout) and then you will repeat the question. When a timeout occurs there is a heavy time penalty incurred because TCP falls over to a TCP slow start (talks slower in the hope of being better understood) and a slow start has a large impact to data flow over a much longer time period. Also if the trip latency is high end-to-end then the penalty is more severe because the time incurred for the penalty is higher. This is a bit like leaving your passport behind when you go to the airport for a flight. The cost of recovery will be longer the further away from the airport you live. If you live a mile away returning home to get the passport has a smaller impact to living 100 miles away. Equally the TCP slow start that is invoked as a result of a timeout injects a longer recovery time for the slow start ramp to get back to the full data flow speed (called a TCP episode). Need more help or have questions, please contact us. |