"Suggestion for a QoS Metric "

Cornelia Kappler

Information Communication Mobile
Siemens AG, Berlin, Germany

Andrew Reeve

Roke Manor Research, Romsey, UK


The term QoS is not well defined in the sense of a measurable quantity. Yet it is desirable to be able to quantify QoS: Service Level Agreements(SLA) include QoS.

Hence it necessary to be able to measure QoS and to quantify the violation of an SLA. In the Internet Draft "draft-tequila-sls-00", a (QoS) performance guarantee, to be eventually included in an SLA, is specified. It includes guaranteed throughput, bounds on delay, jitter and packet loss, as well as a precise description of how to measure these quantities.

We suggest a simple QoS metric based on such a performance guarantee. Particularly, we suggest measuring the percentage of packets which satisfy all aspects of the performance guarantee. If n% of the packets of a flow satisfied the performance guarantee, the flow received n% QoS.