ATM Overview

ATM Overview

ATM is a connection-oriented, unreliable (does not acknowledge the receipt of cells sent), virtual circuit packet switching technology. Unlike most connectionless networking protocols, ATM is a deterministic networking system — it provides predictable, guaranteed quality of service. From end to end, every component in an ATM network provides a high level of control. ATM technology includes:

• Scalable performance. ATM can send data across a network quickly and accurately, regardless of the size of the network. ATM works well on both very low and very high-speed media.
• Flexible, guaranteed Quality of Service (QoS). ATM allows the accuracy and speed of data transfer to be specified by the client. This feature distinguishes ATM from other high-speed LAN technologies such as gigabit Ethernet. The QoS feature of ATM also supports time dependent (or isochronous) traffic. Traffic management at the hardware level ensures that quality service exists end-to-end. Each virtual circuit in an ATM network is unaffected by traffic on other virtual circuits. Small packet size and a simple header structure ensure that switching is done quickly and that delays due to high traffic are minimized.

• Unobstructed speed. ATM imposes no architectural speed limitations. Its pre-negotiated virtual circuits, fixed-length cells, message segmentation and re-assembly in hardware, and hardware-level switching all help support extremely fast forwarding of data.
• Integration of different traffic types. ATM supports integration of voice, video, and data services on a single network. ATM over Asymmetric Digital Subscriber Line (ADSL) enables residential access to these services.