High short-term bit-rates from TCP flows

Micro-bursts from TCP flows are investigated. The chip-rate is introduced and used to quantify the short-term bit-rate of TCP flows. This paper examines packets with chip-rates above the 90^th percentile. The examination is performed over time scales ranging from 244 μs to 125 ms. Two issues are addressed, the impact and the causes of the micro-bursts. It is found that the packets with high chip-rate experience an elevated probability of burst losses. For example, the probability of a burst loss is up to 10 times larger for packets sent in micro-bursts. Furthermore, in some settings, these packets experience higher loss rate in general. It is also found that micro-bursts cause an increase in queuing delay. The causes of these micro-bursts are investigated. One finding is that at short-time scales, ACK clocking, which should reduce micro-bursts, is not functioning correctly. For example, in some cases, most of the packets contained in micro-bursts are ACKed at a rate that is less than half of the data rate.