Dual-bus metropolitan area networks (MANs) are well suited to provide broad-band network access and network interconnection over a city area by functioning as distributed broadband multiplexers between existing corporate/public networks, multi-media terminals, and broadband integrated services' digital networks employing an asynchronous transfer mode. The authors address the important problem of integrating time-sensitive and non- time-sensitive traffic over MANs. In the proposed integration scheme, time-sensitive variable bit-rate isochronous (VBRI) traffic, such as voice and video, is statistically multiplexed over the MAN by a novel, reservation-arbitrated (RA) access protocol, while non-time-sensitive asynchronous traffic, such as data, is transported over the residual bandwidth by queue-arbitrated access. RA access allows a VBRI traffic source to capture and reserve some isochronous channels on a bandwidth-on-demand basis. Compared to previously proposed reservation protocols, RA access is fair, provides a better isochronous transport service, and is compatible to the slot format of the existing IEEE 802.6 MAN standard. The system performance is analysed by an approximate theoretical model and computer simulations. Results indicate that the proposed integration scheme can be engineered to meet the stringent quality of service requirements of the time-sensitive VBRI traffic, while providing a satisfactory service to the non-time-sensitive data traffic and ensuring efficient bandwidth utilisation.
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