Glossary

Types of Network Topologies Explained

A network topology is the layout in which computers and networking hardware (switches, routers, etc.) are connected together. Different network topologies offer various benefits to the business, such as better efficiency or increased resiliency. Selecting the right network topology is important to ensure that a corporate network meets business needs.

Physical vs. Logical Network Topologies

A network topology describes how a network is laid out and how traffic can flow through the network. However, in some cases, these are two different things. A network can have both a physical and a logical topology, both of which have an impact on the network’s layout, performance, and availability.

Physical Network Topology

A physical network topology lays out the collection of cables and switches that make up an organization’s physical network infrastructure. For example, an organization may have a subnet laid out so that all of the computers on the subnet are connected to a central switch, which provides access to the public Internet.

This design is an example of a star topology. Other options for physical network topologies include bus, ring, tree, and mesh, which we will touch on below. 

Logical Network Topology

In addition to a physical topology, a corporate network may also have a logical topology. With virtual local area networks (VLANs), software-defined networking (SDN), and similar tools, an organization can use software to define how traffic can flow over the physical network.

With these tools, an organization can create a logical network topology that differs significantly from the physical layer. For example, two devices attached to the same switch may be unreachable from one another due to routing rules defined at the software level. In contrast, two geographically distant sites can behave as part of the same LAN if they are linked together with a virtual private network (VPN). 

Common Types of Network Topologies

Physical network topologies can be laid out in a few different ways. As we previously mentioned, the most common physical network topologies include bus, ring, star, tree, mesh, and hybrid topologies. Let’s take a closer look at each:

Bus Topology

In a bus topology, all of the devices on the network are connected to a central bus or cable that carries their traffic. The main advantages of a bus topology are that it is the cheapest and most resource-efficient network topology, and the network can be extended by adding more cable. 

However, it also has its disadvantages. One is that the cable is a single point of failure within the network, causing all devices to lose network access if it fails. Additionally, the cable has limited bandwidth, so network performance decreases as the number of devices connected to the cable increases.

Ring Topology

In a ring topology, devices are connected in a circle, with each device connected to its two neighbors. Traffic flows in one direction around the ring. These types of networks are easy to set up and can handle large traffic volumes well.

However, a ring topology is highly sensitive to potential disruptions. Any computer in the network is a single point of failure, and adding or removing devices disrupts network communications.

Star Topology

In a star network, every computer in the subnet is directly connected to a switch or router. This device is then connected to a higher-level switch or provides direct access to the public Internet. Star topologies are a commonly used network topology because they’re easy to set up and maintain. Adding or removing devices from the network doesn’t disrupt the network, and no end-user device is a potential single point of failure.

However, star topologies are more expensive than some other topologies due to the need for additional cabling and a central switch. Additionally, the router/switch at the center of the subnet is a single point of failure.

Tree Topology

A tree topology combines elements of a bus and star topology. The network has a central trunk line with branches connected to it. This creates a hierarchical structure within the network.

Tree topologies are easily expandable and have the ability to isolate individual branches of the tree from the rest of the network. However, the top level of each branch is a single point of failure for the rest of the branch, and these topologies tend to be more difficult to set up.

Mesh Topology

Mesh topologies directly connect devices to one another in a peer-to-peer network. Mesh networks can have varying levels of interconnectivity, up to a full mesh where every device is connected directly to every other device. Mesh topologies are the most reliable and fault-tolerant network infrastructure since many paths exist between any two devices. This makes them ideal for situations requiring redundancy and high availability.

However, mesh networks are also the most expensive type of network. They require the most cabling to set up and can be difficult to configure and maintain.

Hybrid Topology

Hybrid topologies combine elements of multiple base topologies. For example, a tree topology is technically a hybrid between a bus and a star topology.

Companies implement hybrid topologies to take advantage of the various benefits of the different topologies. For example, an organization may use a mesh in a network segment where availability is critical but use a star or bus elsewhere to save money.

While physical topologies have remained largely the same for years, the introduction of new technologies has had a significant impact on logical network topologies. Some emerging trends that are changing how networks are structured and used include the following:

  • Intent-Based Networking: Intent-based networking uses artificial intelligence (AI) and machine learning (ML) to automatically manage a corporate network. At the logical level, intent-based networking can define network topologies based on the business needs for that network.
  • Software-Defined Networking (SDN): SDN allows network topologies and routing to be defined and managed using code at the logical level. This enables organizations to create much more flexible network topologies that adapt to changes in IT infrastructure and business requirements.
  • Internet of Things (IoT): IoT devices collect large volumes of data and need high-performance connectivity to systems that process this data and issue commands. As IoT devices grow more common, companies need network topologies that can scale to support them and that offer an acceptable level of network availability and resiliency.
  • Edge Computing: The growth of 5G and edge computing means that processing power is increasingly moving to the network edge, near the IoT devices and other systems that need it. This impacts decisions regarding network topologies since devices may need high-performance connectivity to their near neighbors rather than centralized infrastructure.

Network Topology Mapping and Monitoring Best Practices

Network topology mapping can be useful for understanding and optimizing the structure of the corporate network. These visualizations should also be documented to support troubleshooting efforts and make it easier to manage the network in the future.

While it’s possible to map network topologies by hand, tools are available that automatically generate these visualizations. Taking advantage of these tools and implementing network monitoring best practices can improve corporate network visibility and performance.

Network Topology Mapping Tools

Numerous network topology mapping tools are available. Some commonly used options include:

  • SolarWinds Network Topology Mapper.
  • N-able N-central Network Mapping Software.
  • LibreNMS.
  • NetDisco.
  • Domotz.
  • Nmap.

In general, these tools operate as network scanners, using various network protocols — ICMP, TCP, SNMP, etc. — to detect and identify systems connected to the network and their locations. Based on the collected information, they can produce a visualization of the network.

In most cases, the available tools offer a tradeoff between cost, network size, and features. Some tools can scan a limited number of hoists, and others provide additional features, such as the ability to generate multiple maps from a single scan or a complete device inventory. Companies should select a tool based on their available budget and resource requirements.

Network Monitoring Best Practices

Continuous network monitoring is essential to identify potential issues with the corporate network and address them before they cause downtime or other undesirable effects for the business. Some network monitoring best practices to implement include the following:

  • Establish Performance Baselines: Network performance is impacted by various factors, including network topology, cable types, and the devices used. Baselining network performance is important to help the organization identify potential issues with the network.
  • Configure Alerts: If a device goes down, it affects the usability of the network, especially in topologies with a single point of failure. Configuring automated alerts to warn of potential issues enables the networking team to act quickly and minimize downtime and other impacts on the organization.
  • Proactively Optimize and Troubleshoot: SDN and logical topologies provide organizations with a great deal of flexibility in their network infrastructure. Companies can take advantage of this by proactively optimizing and troubleshooting their networks to maximize performance and reliability.

How to Select the Right Topology for Your Network

Networks can be laid out in various topologies, and each has its own pros and cons. When considering which topology to select, keep the following in mind:

  • Consider Growth: Some network topologies offer greater scalability than others, and adding or removing devices can impact network connectivity in some topologies. When selecting a topology, consider whether the network is expected to stay largely stable or grow over time.
  • Assess Performance Requirements: Network topologies differ in the level of performance they can offer and which types of communications are most performant. For example, mesh topologies offer extremely fast communications between different devices but are also more expensive and complex to implement.
  • Consider Reliability: Different networks also have varying reliability requirements. For example, critical infrastructure networks require high availability, so a network topology that minimizes single points of failure would likely be the best choice for them.
  • Determine Resource Constraints: All network topologies have their tradeoffs, and more reliable or high-performance topologies often require additional cabling and devices. Determining budget and resource constraints in advance can help with selecting a network topology or developing a custom one that provides the best balance of features and expense.
  • Evaluate Management Overhead: Some network topologies are simple to set up and manage, while others are more complex. When selecting a network topology, it is important to consider whether the company has the expertise and resources required to configure it correctly and to maintain it throughout its lifetime.
  • Define Logical Topologies: Thanks to SDN, an organization can use a combination of physical and logical topologies to better support business needs. For example, an organization could use a more resilient physical topology — like mesh — to improve availability but use SDNs to layer a different logical topology on top of it to better fit the roles of connected devices.

Conclusion

A network topology can either be the layout of physical cables and devices or a software-defined logical network layout. Different topologies and solutions have their own pros and cons, so IT leaders should carefully consider which topology to use in their systems to ensure that it meets the needs of the business.

While the various physical topologies have existed for decades, emerging technology has driven innovation in logical topologies. The growth of SDN, IoT devices, and edge networking all contribute to significant changes in how networks are structured and how data flows over the underlying physical infrastructure.

Cato SASE Cloud enables companies to customize and optimize their corporate WAN with built-in SD-WAN capabilities. SD-WAN optimally routes traffic between distributed LANs, offering improved performance and simplified routing within the corporate WAN.