Six popular network topology types

No two networks are designed and built alike. One enterprise's network deployment goals may be drastically different from another. Network professionals need to tailor each system to meet access, control, and performance levels based on business goals.

That said, enterprise-class network technologies have their own limitations, so network professionals must build networks based on how the equipment operates. Most network topologies (including network equipment and complementary software) are flexible, but they also have some specific deployment methods.

Below are six popular types of network topologies. Some are traditional and rarely used, while others are newer and offer greater performance, reliability, and security. Let's look at each topology type and how each operates.

1. Bus network topology

The bus network topology consists of a flat network where all devices (called stations) are directly connected and transfer data between each other. From an intelligence point of view, bus networks are simple in nature when it comes to transmitting and retransmitting data.

When one station transmits data, the bus automatically broadcasts it to all other stations. Only the destination station accepts the transmission; all other devices recognize that the traffic is intended for them and ignore the communication.

However, despite its simplicity, the bus topology is sometimes inefficient because it broadcasts data to all devices on the network. This can cause network congestion and reduce performance. As a result, bus networks are rarely used in modern enterprise environments.

2. Ring network topology

Ring topology is a configuration where each device is directly connected to two other devices on the network, forming a continuous circle in a non-hierarchical structure. Data sent to a specific device is transmitted from one device to another in the ring until it reaches its intended destination. In some cases, data is transmitted in a single direction in the ring. In other cases, the transmission occurs in both directions.

In the early days of Token Ring networks, data would travel around the ring, touching each endpoint network interface card until the data reached its destination. Today, ring networks, such as Synchronous Optical Networks, consist of network switches that form a ring.

3. Mesh network topology

Mesh topology is another non-hierarchical structure where each network node is directly connected to all other nodes. Mesh topology ensures tremendous network resiliency because if a connection is broken, there is neither an outage nor a loss of connectivity. Instead, traffic is simply rerouted along a different path.

However, the downside of using a mesh topology is that it increases the complexity of the architecture. If the mesh uses wired links, this can also significantly increase the amount of network cables required. To avoid cabling issues, enterprises often subsume mesh networks to wireless systems, such as Wi-Fi-based mesh deployments.

4. Star network topology

Star topology, also known as hub-and-spoke topology, uses a central node - usually a router or a Layer 2 or Layer 3 switch. Unlike a bus topology, which simply broadcasts transmitted frames to all connected endpoints, a star topology uses components with additional levels of built-in intelligence.

Layer 2 switches maintain a dynamic media access control (MAC) address table in a star topology deployment. This table maps the MAC address of a device to the physical switch port to which it is connected. When a packet is transmitted to a specific MAC address on the LAN, the switch performs a MAC address table lookup to determine the destination port for the frame. This significantly reduces unnecessary broadcast traffic that can create bottlenecks.

Using a layer 3 device as a star topology center node enables IP addressing and routing tables to target and send traffic forwarding to a single destination.

5. Tree network topology

A tree topology is a hierarchical structure where nodes are linked and arranged like a tree when drawn in the form of a network diagram. Network professionals typically deploy a tree topology with a core layer, distribution layer, and access layer.

At the top of the tree is the core layer, which is responsible for high-speed transmission from one part of the network to another. The distribution layer in the middle of the tree performs similar transmission duties as the core, but at a more localized level. The distribution layer is also where network administrators apply access control lists and quality of service policies. At the bottom of the tree is the access layer, where endpoint devices connect to the network.

Leaf-spine network topology is a tree topology that is becoming increasingly popular in data centers. Leaf-spine topology adheres to the hierarchical structure of the tree model but has only two layers instead of the traditional three. Leaf-spine network switch components are responsible for high-speed transmission throughout the data center; leaf switches are perfectly matched with spine nodes and are responsible for connecting application, database, and storage servers to the data center.

6. Hybrid network topology

Enterprise networks often use more than one type of network topology. One topology may be preferable to another, depending on factors related to performance, reliability, and cost. For example, a network professional might configure a wireless LAN that uses a star topology for most network connections but also uses a wireless mesh network in certain situations, such as when network cables cannot be run to an access point.