Token ring network

What is a token ring network?

A token ring network is a type of local area network (LAN) in which devices are arranged in a logical ring and take turns transmitting data using token passing. Only the device holding the token can transmit at any given time, ensuring orderly communication.

The ring is logical rather than always physical. Devices connect in a star configuration to a central hub called a multistation access unit (MAU), which manages node connections and maintains ring continuity if a device fails. Token ring networks were common in IBM enterprise environments but are now considered legacy technology.

How does a token ring network work?

A small control frame called a token circulates continuously around the ring. When a device receives the token, it can attach data and send it along the ring. The destination device copies the data as it passes and marks the frame as received. The originating device sees this acknowledgement, removes the frame from the ring, and releases the token for the next device to use.

A designated device on the ring acts as the active monitor (AM), which detects conditions such as token loss and can generate a new token if necessary to restart communication. Token ring network diagram showing computers in a logical ring.

Token ring vs. Ethernet

While popular in the 1980s and 1990s for its reliability, token ring was largely replaced by Ethernet.

Aspect	Token ring	Ethernet
Access method	Token passing	Carrier sense multiple access with collision detection (CSMA/CD)
Collisions	None	Possible (rare in modern switched networks)
Performance under load	Predictable and stable	Can degrade with congestion
Speed	4–16Mbps	10Mbps to multi-gigabit
Cost	Higher	Lower
Current use	Legacy	Standard

Ethernet became the dominant standard because it is simpler, faster, and more cost-effective, while still offering strong performance in modern switched networks.

Why is token ring important?

Token ring networks introduced a structured method of controlling network access that reduced collisions compared to early Ethernet systems and improved stability in shared network environments.

Token ring also provides useful context for understanding how modern networking technologies evolved. It remains relevant for maintaining older network infrastructures and supporting networking education and certifications.

Where is it used?

Token ring networks are now limited to legacy environments, including:

Older enterprise systems originally built on IBM networking technologies.
Industrial systems that have not been upgraded.
Educational settings for teaching networking concepts.

Limitations

Token ring networks have several practical drawbacks compared to modern networking technologies:

Slower speeds than modern Ethernet.
Configuration errors can disrupt network operation.
MAU failure or token loss can interrupt communication across the ring.
Limited compatibility with modern hardware and security controls.
Higher cost and complexity.
Increasing difficulty in sourcing replacement components.

FAQ

What is a token in networking?

A token is a small control frame that circulates continuously through the network and grants permission to transmit data to the device that currently holds it.

Is a token ring network still used today?

Token ring networks are rarely used today. They remain only in legacy systems where replacing the infrastructure is costly or impractical.

How is token ring different from Ethernet?

Token ring uses token passing to control access, allowing only one device to transmit at a time. Ethernet uses collision detection and, in modern switched networks, supports simultaneous transmissions across multiple devices. Ethernet is generally simpler, faster, and more cost-effective.

Why did token ring networks decline?

Token ring networks declined as Ethernet became more scalable and affordable. As Ethernet technology improved in speed and efficiency, its practical advantages outweighed the predictable performance benefits of token ring.

Is token ring secure by modern standards?

Token ring is not considered secure by modern standards. It was developed before current cybersecurity practices and lacks built-in protections, requiring additional measures to meet today’s security requirements.