What is the architecture of Asynchronous Transfer Mode?

ATM is a connection-oriented network at a point where the sender or user which access devices are known as end-point, these end-points connected through a user to network interface (UNI) to the switches on the network, these switches provide a network to network interface (NNI).

The architecture of the ATM is shown in the figure below.

ATM transfers the information through a transmission path which is made up of a logical virtual path and virtual channel. The transmission path consists of the physical cable, which is connected to an ATM switch. The cables have a transfer speed of up to 155 megabits per second on an optical fiber link.

Virtual Path

The transmission path is logically divided into separate virtual paths identified using the virtual path identifier (VPI) in the ATM header.

Virtual Channel

The bandwidth of a logical virtual path is further divided into a separate channel. Each channel is given a virtual channel identifier in the ATM header.

Traffic flow through the Network

A two-tiered addressing design is used with the following elements being contained in the addressing assignments.

• Virtual Channel: A virtual channel represents the structure of a single network connection data flow between two ATM end-users. The ATM standards represent this as a unidirectional connection between two end-points on the network.
• Virtual Path: A virtual path can carry one or more virtual channels by the network. It is represented as a group of channels between the two end-points.