Ring Topology: Working, Types, Advantages, Disadvantages & Applications Explained

Introduction

Ring topology is a network configuration in which each node is connected to exactly two other nodes, forming a circular pathway for signal transmission. Data travels from node to node, with each device processing one packet at a time.

Ring networks may be unidirectional (data flows in one direction—clockwise or anticlockwise) or bidirectional as seen in SONET/SDH systems. In a unidirectional ring, a single link failure can disrupt the entire network.

To prevent this, some ring networks use a counter-rotating ring (C-Ring) to provide redundancy. During a failure, data is rerouted through the complementary ring, ensuring continuous connectivity. Examples of dual-ring networks include SS7, FDDI, Spatial Reuse Protocol, and Resilient Packet Ring.

IEEE 802.5 Token Ring networks solved limitations of physical ring topology by using a star-based structure with a Media Access Unit (MAU) to emulate a ring at the data-link layer.

In many SS7 and SONET/SDH rings, two sets of bidirectional links enable maintenance work and link failures without interrupting primary traffic.

How Data Travels in a Ring Network

Data packets travel from one device to another until they reach the destination node. Once the packet reaches its destination, it is copied, and when it returns to the sender after completing a full circle, it is removed.

Each node in the ring has equal access to the media. However, if one node fails to pass the data further, the entire network may fail—unless redundancy mechanisms are in place.

How Is a Ring Topology Formed?

Each device in a ring is connected to two other devices, forming a circular data path. Data moves step-by-step from one device to the next until it reaches the destination.

Some ring networks use token-passing to manage access, such as Token Ring Topology. It is also known as Active Topology because all nodes must remain active for communication to continue.

Repeaters are often added in larger rings to avoid data loss and maintain signal strength.

Types of Ring Networks

1. Unidirectional Ring (Half-Duplex)

Data flows in only one direction—either clockwise or counter-clockwise. This is common in simple ring networks.

2. Bidirectional Ring (Dual Ring)

Also known as a dual-ring network, two connections between nodes allow data to flow in both directions. If one path fails, the alternate ring ensures communication continues.

Media Access Protocols in Ring Networks

Ring networks can transmit packets, circuits, or both. SDH rings carry circuits configured with out-of-band signaling, while packet transmission uses MAC protocols.

Three types of media access protocols used in ring networks are:

1. Slotted Ring

The network’s latency is treated as a continuously rotating shift register divided into fixed-size slots. Stations look for empty slots to insert data. The slot is freed when the destination copies the data or when it returns to the source. The Cambridge Ring is a well-known example.

2. Token Ring

A token circulates around the ring granting permission to transmit. Only the node holding the token can send data.

3. Register Insertion

A station inserts data directly into the ring using a register mechanism, which helps manage traffic efficiently.

Advantages of Ring Topology

• Reduced chances of data collision as data flows in one direction.
• No need for a central server to control network connectivity.
• Devices can be added without affecting overall performance.
• Faults are easier to isolate due to the circular structure.
• Handles high-traffic environments better than bus topology.

Disadvantages of Ring Topology

• Data must pass through each device, which may slow performance.
• A single device failure can bring down the entire network.
• Cabling and setup are more complex.
• Bus topology is often cheaper to install.

Applications of Ring Topology

• Used in both LANs and WANs.
• Common in SONET fiber networks in telecom.
• Often used as a backup topology in enterprise networks.
• Helps reroute traffic using bidirectional rings when a node fails.
• Used in educational institutions due to low operating cost.