An ATM WAN for CSCW applications: The BETEUS Network (Broadband Exchange for Trans-European USage)

Multimedia is an important issue that drives the request for ATM (Asynchronous Transfer Mode) communication. The usage of multimedia features in a collaborative work environment is the core of BETEUS - Broadband Exchange for Trans-European USage. In this paper we discuss the design and implementation of the BETEUS communication platform. BETEUS is a european project funded by the EC which is aiming at providing a platform for the support of CSCW applications such as tele-teaching, tele-meeting or tele-seminar. The communication platform is the part of the overall BETEUS platform that provides end-to-end connectivity between BETEUS sites. The realization of the communication platform is constrained by the services available on the European ATM pilot. The development of the BETEUS application platform is independent from the actual support of the underlying communication infrastructure. Although all BETEUS user sites run FORE ATM 200 switches, this was not obvious when the design of the communication platform was started. But, at that time, it was apparent that IP connectivity was available for all partners either directly over ATM or SMDS (Switched Multimegabit Data Service). The communication platform can be extended so that IP multicast facilities can be used for point-to-multipoint communication as is requested by tele-teaching applications. The paper discusses the services offered by the European ATM pilot. Since the BETEUS communication platform is designed to provide reliable connectivity between BETEUS user sites, sites are connected by a fully meshed network using ATM VPs (Virtual Path), i.e. permanent virtual channels (PVC). PVCs are based on the semi-permanent virtual path service (Section 2.2). Such a service has been considered most appropriate with respect to the design considerations of the BETEUS communication platform.