DTM — A True Broadband Concept Based on Fast Circuit Switching

The paper discusses the use of fast circuit-switching in future highcapacity networks. We believe that the capacity and the size of the public network will increase to an extent where it is infeasible to rely on bandwidth optimization and dynamic congestion control mechanisms [8]. Dynamic synchronous Transfer Mode (DTM) is a new protocol suite based on synchronous fast circuit switching. It is designed for high-speed networks running at several gigabits per second. We believe a large part of the traffic in future high-speed integrated networks will result from real-time applications, such as video and audio. We argue that a circuit-switched network with variable channel sizes such as DTM is well suited to provide real-time services. To avoid the static nature of ordinary circuit-switched networks, DTM uses dynamic allocation of resources among the nodes in the network. Resources are reallocated according to user demands. Many of the new services for broadband networks are either distributive, such as cable TV, or multiparty applications, such as teleconferencing and CSCW. An important feature for broadband networks is therefore to provide means for efficient multicast. Synchronous networks have to provide an asynchronous service to support variable packet lengths. This may be provided by a segmentation and reassembly (SAR) protocol. In DTM, the SAR protocol is simplified by the fact that the DTM network does not reorder or lose data.