On allocation schemes for the interconnection of LANs and multimedia sources over broadband networks

One fundamental difference between traditional telecommunications networks and traditional data networks is the level where statistical multiplexing takes place. The LAN world uses broadcast topologies, shared media and statistical multiplexing is performed inside the network. The traditional telecommunications world uses dedicated point-to-point links and the customers compete for resources before entering the network nodes. THe current ATM paradigm for B-ISDN inherits a lot from the telecommunications environment but ironically enough its first applications are expected to be the broadband (ATM) LAN and the interconnection of LANs over wide areas. In order to allow for statistical gains, the dedicated links have been transformed into virtual connections which share the physical transmission medium, but without an access coordination mechanism similar to the MAC in LANs. Instead, a host of bandwidth allocation and congestion control schemes are used, which are largely based on a statistical measure of the characteristics of the individual and aggregate traffic streams. The paper presents a critical survey of the tools available to explore the multidimensional allocation space and to characterize the blocking properties of the broadband shared resource environment when carrying traffic generated by heterogenous sources and in particular by interconnected LANs.