Token Ring is a network topology and protocol used in local area networks (LANs) to connect devices in a ring or star topology. Developed in the early 1980s by IBM, Token Ring was an alternative to Ethernet, another popular LAN technology. Token Ring networks were widely used during the 1980s and 1990s but have largely been replaced by Ethernet in modern networking environments.
Key features and concepts of Token Ring:
- Ring Topology: In a Token Ring network, devices are connected in a physical or logical ring. Each device is connected to exactly two others, forming a continuous loop. Data travels around the ring from one device to another in a unidirectional or bidirectional manner.
- Token Passing Protocol: Token Ring uses a token passing protocol to control access to the network. A token is a small data packet that circulates around the ring. Only the device in possession of the token is allowed to transmit data. When a device wants to send data, it must wait for the token to arrive at its position in the ring.
- Predictable Performance: Token Ring offers more predictable and consistent network performance compared to Ethernet, especially under heavy network loads. This is because devices take turns transmitting data based on the token, reducing the likelihood of collisions.
- Reliability: Token Ring networks are known for their reliability. They can quickly detect and isolate faults or failures in the network, allowing for rapid recovery.
- Data Integrity: Token Ring networks typically provide higher data integrity because they use a token passing mechanism. This means that only one device can transmit at a time, reducing the chances of data collisions.
- Speeds: Token Ring networks were initially designed to operate at 4 Mbps (megabits per second). Later, standards such as Token Ring IEEE 802.5 introduced 16 Mbps and 100 Mbps variants.
- Connectors: Token Ring networks often used specialized connectors, such as IBM’s Type 1 or Type 3 connectors. These connectors provided a physical connection between devices and allowed the network to maintain its ring topology.
- Legacy Technology: While Token Ring was widely used in the past, it is now considered a legacy technology. Most modern networks, including LANs and data centers, use Ethernet due to its higher speeds, widespread industry support, and cost-effectiveness.
- Migration to Ethernet: Many organizations that once used Token Ring networks have migrated to Ethernet-based solutions, as Ethernet has evolved to offer faster speeds and improved performance.
Token Ring networks, with their predictable performance and data integrity, had their advantages, but they were more expensive to implement and maintain than Ethernet. As a result, Ethernet became the dominant LAN technology and is now the standard for wired LANs worldwide. While Token Ring is no longer commonly used in new network installations, it remains an important part of networking history.