Representative Delay Measurements (RDM): Facing the Challenge of Modern Networks

Abstract

Network access technologies have evolved significantly in the last years. They deploy novel mechanisms like reactive capacity allocation and time-slotted operation to optimize overall network capacity. From a single node's perspective, such optimizations decrease network determinism and measurement repeatability. Evolving application fields like machine to machine (M2M) communications or real-time gaming often have strict real-time requirements to operate correctly. Highly accurate delay measurements are necessary to monitor network compliance with application demands or to detect deviations of normal network behavior, which may be caused by network failures, misconfigurations or attacks. This paper analyzes factors that challenge active delay measurements in modern networks. It introduces the Representative Delay Measurement tool (RDM) that addresses these factors and proposes solutions that conform to requirements of the recently published RFC7312. Delay measurement results acquired using RDM in live networks confirm that advanced measurement methods can significantly improve the quality of measurement samples by isolating systematic network behavior. The resulting high-quality samples are one prerequisite for accurate statistics that support proper operation of subsequent algorithms and applications.

The Right Time: Reducing Effective End-to-End Delay in Time-Slotted Packet-Switched Networks

“…All measurements use an allocated dedicated radio channel. Client and server implementations of the Representative Delay Measurement Tool (RDM) [21] generate the traffic according to predefined scenarios and accurately record start time and measured delay.…”

“…The measurement methodology builds on the one used in the analysis of the randomness cancellation effect [16], [21]. The RDM client running on the laptop sends packets according to a precomputed scenario that defines a priori send time, payload size, and artificial wait time within the reflecting server for all 20 000 measurement packets.…”