FDDI (Fiber Distributed Data Interface) is a high-speed networking technology designed for use in local area networks (LANs). It operates at the physical layer (Layer 1) and the data link layer (Layer 2) of the OSI model, providing reliable and high-performance data transmission capabilities.
Key Features and Components of FDDI:
- Dual Ring Topology:
- FDDI networks typically use a dual ring topology for redundancy and fault tolerance. There are two counter-rotating rings: a primary ring and a secondary ring.
- Data is transmitted in one direction on each ring (counter-clockwise on one ring and clockwise on the other).
- Physical Medium:
- FDDI networks use optical fiber cables as the primary physical medium for data transmission. This choice of medium provides high bandwidth and immunity to electromagnetic interference, making it suitable for high-speed data communication.
- Transmission Speed:
- FDDI supports transmission speeds of up to 100 Mbps (Megabits per second), which was considered very high-speed during its introduction in the 1980s and 1990s. It offers ample bandwidth for multimedia applications, large file transfers, and high-volume data traffic.
- Token Passing Protocol:
- FDDI uses a token passing protocol for media access control (MAC), similar to Token Ring networks. The token circulates around the ring, granting devices permission to transmit data when they possess the token.
- This approach ensures fair access to the network and prevents data collisions, contributing to reliable and efficient data transmission.
- Fault Tolerance and Reliability:
- The dual ring topology in FDDI provides built-in fault tolerance. If a break occurs in the primary ring, data can automatically reroute through the secondary ring, maintaining network connectivity.
- This redundancy minimizes downtime and enhances network reliability, crucial for mission-critical applications.
- Connectivity and Scalability:
- FDDI supports a large number of nodes (up to 500 devices) in a single network segment, making it scalable for growing network environments such as enterprise LANs and campus networks.
- Devices can connect to the FDDI network through concentrators or hubs, which manage connections and ensure efficient data distribution.
- Standards and Compatibility:
- FDDI is standardized by the ANSI (American National Standards Institute) as ANSI X3T9.5 and is also recognized by the ISO (International Organization for Standardization) as ISO 9314.
- It provides interoperability with other networking technologies and protocols, facilitating integration into diverse network environments.
Applications of FDDI:
- Enterprise Networks: Used in large organizations and enterprises for connecting multiple buildings or departments within a campus environment.
- Backbone Networks: Deployed as a backbone infrastructure to interconnect various LANs and provide high-speed data transfer between different network segments.
- Mission-Critical Applications: Suitable for applications requiring high reliability, fault tolerance, and high bandwidth, such as financial transactions, data centers, and multimedia content delivery.
In summary, FDDI is a robust and scalable networking technology designed to meet the demands of high-performance LANs, offering high-speed data transmission, fault tolerance, and reliability through its dual ring topology and token passing protocol.
While newer technologies like Ethernet have largely replaced FDDI in modern LAN deployments, its architectural principles and design concepts continue to influence network design and implementation practices
