ATM NETWORKS

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In recent years, computer systems have achieved an almost explosive increase in performance, such that developments in the field of data communications have been unable to keep up. Where the processor performance and memory capacity of PCs have grown over the past ten years by a factor of a hundred, transfer speeds in wide area networks have risen only by a factor of ten, and in LANs they have been stayed much the same. ATM is a standard recognized throughout the world, which provides for the first time a method for universal information exchange, independent of the end system and the type of information (data, audio, video). 

The architecture of ATM (53 byte cells) supports the design of massive parallel communication architectures and enables the implementation of networks with transfer rates in the gigabit range. With the high speed networks, it is possible to send huge quantities of data generated by the latest applications (video mail, interactive TV, virtual reality, etc.). ATM is suitable for local area networks as well as wide area networks.

The ability of ATM to emulate traditional LAN and WAN architectures will ensure a smooth transition from today's computer network infrastructure to ATM-based high-speed technology. The intense development efforts being made all major manufacturers of data communication systems in the area of ATM/B-ISDN are evidence of the strategic importance to the industry of this new transmission technology. ATM is increasingly being adopted as the central strategic technology for data communication throughout the industry today.

ATM opens the possibility of designing networks with transmission speeds up to the physical limits. ATM networks with bandwidths approaching the bandwidth of light (30 Terahertz) are imaginable and ATM switches with processing speeds of up to 1 Terabits have already been demonstrated in research laboratories. In ATM we may have on our doorstep the ultimate transfer mechanism in data communications.

PRINCIPLE OF ATM

ATM - originally designed for WAN communications, but quickly adapted for LANs as well, ends this historical separation and forms a universal platform for data communication, In both ATM LAN AND ATM WAN networks the data transport is achieved via connection-oriented communication paths, which are set up though high-speed switching systems. These ATM switches perform the cell routing from the input ports of the switch to the destination port in real time and in parallel for the ports.

For data transport ATM uses packets with a fixed length of 53 bytes, the so-called cells. These cells can be processed significantly faster and more efficiently in switching systems than data packets of variable length. Because of the cell structure, a massive parallel architecture of ATM switching systems is possible. Since all cells have the same length, all data units which wait at the input ports of a switch for transportation at a given time, can be routed simultaneously to their destination port. ATM can handle all of today's data services (telephone, data, video-broadcast and interactive) in an efficient way.

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