This paper presents a QoS evaluation in a DiffServ experimental test-bed scenario. We implemented our field trial using prototypal routers running under Linux OS and we arranged them in order to make possible the interconnection with a remote island of a Multi-domain DiffServ network. The performance evaluation of Real-time applications presented in the paper will make clear how it is possible to provide "mission critical" applications with tool-quality level of service when appropriate algorithm and resource sharing are chosen and when these features are associated with a fair degree of aggregation. As a consequence the paper describes the results by means of a Mean Opinion Score (MOS) evaluation campaign to show how Real-Time applications (such as voice and video conferencing) may suffer for the lack of QoS.

Keywords: Experimental test-bed, Multi-Domain, DiffServ, Real-Time traffic.