Asynchronous Transfer Mode (ATM): Pros and Cons

This article explores the pros and cons of Asynchronous Transfer Mode (ATM). We’ll delve into the benefits and drawbacks of ATM, while also providing a basic overview of the technology itself.

What is Asynchronous Transfer Mode (ATM)?

ATM stands for Asynchronous Transfer Mode. This technology facilitates data transmission between a source and destination using ATM cells. Each ATM cell has a fixed size of 53 bytes, consisting of a 5-byte header and a 48-byte data payload.

ATM played a crucial role in the success of Broadband Integrated Services Digital Network (B-ISDN), enabling the transport of voice, data, and video. Unlike Synchronous Transfer Mode (STM), where bandwidth is periodically assigned (like in Time Division Multiplexing or TDM), ATM transmits cells only when data is available for transmission.

ATM is a connection-oriented technology that employs virtual packet switching. This means multiple logical connections can be multiplexed over a single physical connection.

_Figure 1: ATM Network Interfaces

Advantages of Asynchronous Transfer Mode (ATM)

Here’s a look at the benefits of using ATM:

• Versatile Traffic Support: ATM is optimized for transporting voice, data, and video, providing a single network for diverse needs. It effectively handles mixed traffic types, including real-time and non-real-time data.
• Seamless Integration: ATM easily integrates with various network types, including LANs, MANs, and WANs.
• QoS and High Speed: ATM is designed for Quality of Service (QoS) and high-speed data transmission.
• Efficient Bandwidth Usage: It enables efficient use of network resources through bandwidth on-demand allocation.
• Simplified Infrastructure: ATM uses a simplified network infrastructure compared to some alternatives.

Disadvantages of Asynchronous Transfer Mode (ATM)

Here’s a list of the drawbacks associated with ATM:

• Cell Header Overhead: The 5-byte cell header adds overhead to each cell, reducing the effective bandwidth.
• Complex QoS Mechanisms: Achieving QoS requires complex mechanisms, which can increase implementation and management overhead.
• Congestion and Cell Loss: Network congestion can lead to cell losses, affecting data integrity.
• High Equipment Costs: ATM switches are typically more expensive than LAN hardware. Similarly, ATM NICs are pricier than Ethernet NICs.
• Connection Setup Overhead: As a connection-oriented technology, ATM requires time for connection setup and tear-down, which can be longer than the actual data transmission time.