Real time multimedia applications are emerging over networks originally designed to support asynchronous services. The traffic generated by these applications represents a very critical component of the total traffic to be supported by future broadband telecommunication networks. The paper presents the experimental measurements carried out in Italy over a broadband network infrastructure represented by a 140 Mbit/s DQDB MAN. Particular interest was directed to multicast desktop conferencing tools based on software coding of voice and video. The two main traffic components, represented by traditional data traffic and packetized voice and video, were highly variable and bursty. Our measurements show that aggregated traffic offered to the broadband network is well described by self-similar processes which exhibit long range dependence. The interest of this analysis is directed to the performance evaluation of a broadband network which provides a best effort, asynchronous interconnection of several remote LANS. Some relevant effects of the arrival processes on network performances are presented by considering a model of the DQDB IEEE 802.6 network. Our work is directed to point out the need for more realistic traffic scenarios in the analysis of broadband telecommunication networks. rationale behind this choice is that real sources correspond to the multiplexing of several traffic over the network and not to a single isolated video or voice source. This will be particularly true for LAN interconnections that will represent the first service to be provided by broadband networks in a business and educational environment.