How Multimedia Data Transported Over ATM Network?

Asynchronous Transfer Mode (ATM) is a high-speed networking technology that provides a reliable and efficient way to transport multimedia data over a network. It was designed to handle a wide range of multimedia traffic such as voice, video, and data traffic, and has become a popular choice for backbone networks in large enterprises.

In this article, we will discuss how multimedia data is transported over an ATM network.

1. ATM Cell Format:

ATM uses a fixed-length cell format of 53 bytes to transport data over the network. Each cell consists of a 5-byte header and a 48-byte payload. The header contains information about the source and destination addresses, priority, and other control information.

2. Multiplexing:

ATM uses a technique called time-division multiplexing (TDM) to multiplex multiple data streams onto a single physical link. Each stream is assigned a time slot in a round-robin fashion, and data is transmitted in a continuous stream of cells.

3. Virtual Circuits:

ATM uses virtual circuits to establish a connection between two endpoints in the network. A virtual circuit is a logical connection that is created between two endpoints for the duration of a session. It is identified by a unique identifier, called a virtual circuit identifier (VCI) and virtual path identifier (VPI).

4. Quality of Service (QoS):

ATM provides a high degree of QoS by offering different service classes to meet the requirements of different types of traffic. The service classes are defined based on the delay, jitter, and loss characteristics of the traffic. The five classes of service offered by ATM are:

• Constant bit rate (CBR)
• Variable bit rate (VBR)
• Available bit rate (ABR)
• Unspecified bit rate (UBR)
• Guaranteed frame rate (GFR)

5. Segmentation and Reassembly:

ATM uses segmentation and reassembly (SAR) to divide large data packets into smaller segments to fit into the 48-byte payload of each ATM cell. The SAR function reassembles the segments at the receiving end to reconstruct the original packet.

In conclusion, ATM is a reliable and efficient technology for transporting multimedia data over a network. Its use of virtual circuits, multiplexing, QoS, and SAR allows it to handle a wide range of traffic types and ensure that the data is delivered in a timely and reliable manner.