Measurement considerations for assessing unidirectional latencies

Abstract

This paper presents a study of single direction latencies to selected destinations of the Internet utilizing a variety of paths. The objective is to demonstrate that round-trip latencies are an insufficient and sometimes misleading method to determine unidirectional delays. This claim has significant implications for high-speed, multi-application, wide area, traffic aggregating networking environments which often require predictability of precise delay. Keywords: measurement, delay, unidirectional, jitter, latency. 1 Introduction In the Internet community a common method for assessing network latencies is to measure round trip delivery time, the time it takes for a packet to get to and return from a target host. Dividing this value in half to arrive at an outgoing or return latency implicitly assumes that the path to a target host is symmetric. There are both static and dynamic components of transmission latencies which contribute to inaccuracies of this method. Statically, the...