Technology Independent – Service Access Point for QoS Interworking Mario Marchese  , Maurizio Mongelli  , Vincenzo Gesmundo  , Annamaria Raviola   DIST – Department of Communication Computer and System Science, University of Genoa, Via Opera Pia 13 - 16145 Genoa, Italy { Mario.Marchese, Maurizio.Mongelli }@unige.it  Selex Communications S.p.A., via Pieragostini 80 - 16151 Genoa, Italy { Vincenzo.Gesmundo, Annamaria.Raviola }@selex-comms.com Summary. The paper deals with protocol architectures to support mapping of Quality of Service (QoS) between protocol layers of telecommunication networks. A Technology In- dependent – Service Access Point (TI-SAP) is studied to this aim. Inherent TI-SAP map- ping operations introduce the generalization of the regular concept of equivalent bandwidth (EqB). Some performance evaluation is proposed to highlight EqB dimensioning at the TI- SAP interface. 1 Introduction Protocol stacks in telecommunication networks are composed of func- tional layers. Quality of Service (QoS) provision depends on the perfor- mance achieved at each layer and is based on functions performed at layer interfaces. Having in mind the OSI paradigm, QoS derives from reliable physical and link layers that can offer specific transport services to the up- per network layers. The flows generated by the network layers (or bundles of them) are forwarded down to a physical interface that transports the in- formation along a channel. Even if network layer implements efficient QoS mechanisms (IP IntServ, IP DiffServ, MPLS), it is topical that layers below can assure con- nection to the channel with specific degrees of performance. Otherwise the implementation of complex QoS mechanism is useless. As a consequence, the QoS requirements must flow vertically and need to be received and sat- isfied by all the layers of the protocol stack. More specifically, the link