Design , Implementation and Experiences of the OMEGAEnd - Point

New cell-switched network technologies and multimedia peripherals enable distributed applications with strict real-time requirements such as remote control with feedback. Time-bounded network communications services are necessary, but not suucient, to meet application-to-application real-time requirements. Real-time communication must be coupled with real-time computing support at the network end-points. An end-point architecture for this computa-tion/communications coupling must be exible and robust to support a diversity of applications. The OMEGA architecture, when coupled with cell-switched networks (or others which can make bandwidth and delay guarantees), can approximate the behavior of dedicated microcon-trollers connected by dedicated circuits in support of an application. The essence of the OMEGA architecture is resource reservation and management within the set of multimedia endpoints. Communications is preceded by a call-set up period where requirements, expressed in terms of Quality of Service (QoS) parameters, are negotiated, and guarantees are made at several logical levels, such as between applications and the network subsystem, applications and the operating system, and the network subsystem and the operating system. This establishes cus-tomized connections and allocation of resources appropriate to the application requirements and OS/network capabilities. To facilitate this resource management process, a new paradigm called thèQoS Brokerage' is used. This paradigm requires new services and protocols across all layers of the protocol stack (i.e., the higher layers of B-ISDN), as well as rearchitecting the application/network interface. A prototype of OMEGA has been implemented and tested with a master/slave telerobotics application using a dedicated 155 Mbps ATM LAN. This application employs media with highly diverse QoS requirements and therefore provides a good platform for testing how closely one can approximate a dedicated circuit and controller with workstation hosts and cell-switching. Experience with this implementation has helped to identify new challenges to extending these techniques to a larger domain of applications and systems, and raises several new research questions.