Measurement of Processing and Queuing Delays Introduced by a Software Router in a Single-Hop Network

Measurement of main contributions of single-hop delay peculiar to a software router is here dealt with. A method is proposed, capable of distinguishing the time interval during which a generic packet stays in either input or output queue (queuing delay) of the router under analysis and that characterizing the effective routing process (processing delay) the packet undergoes. Thanks to proper measurement probes, i.e. kernel-layer functions, the method makes the occurring time of events of interest available at application-layer, thus giving the possibility of separately evaluating the aforementioned delays and, ultimately, pursuing a deeper insight of the considered router. After brief remarks concerning various delays a packet experiences when passing through a generic router, the measurement principle underling the method is presented in detail. Particular emphasis is put on its capability of locally monitoring the transit of each packet from the input to the output port of a software router along with main features and implementation issues of the proposed measurement probes. Results obtained in many experiments carried out on an ad-hoc test-bed in different operating conditions are then given in order to highlight method's reliability and effectiveness