What is Hub and Spoke Topology?

Quick Definition: Hub and spoke topology is a network configuration where all nodes are connected to a central server, known as the hub, for data exchange and communication. It's a straightforward and cost-effective way of routing and managing data on a network, with the central hub serving as a mediator for all communication, making it easier to configure security settings and monitor traffic. Hub and spoke topology is highly regarded for its simplicity, scalability, and enhanced security capabilities, making it a valuable choice for organizations.

Hub and spoke topology is a network configuration where all nodes are connected to a central server for data exchange and communication. 

A solid grasp of hub and spoke topology — and all network topology types, for that matter — is essential if you plan to take the Network+ exam. Knowing your way around each of the major network topology types will help you become a successful network engineer. In addition to hub and spoke topology, the other main types of network configurations include star, bus, ring, tree, and mesh. Each has its own advantages and disadvantages, and understanding those differences will help you to map and manage your network based on the needs of your organization.

What is Hub and Spoke Technology in Networking?

Before discussing hub and spoke technology, let’s ensure we have a general understanding of what topology means.

What is Network Topology?

Network topology is a term used to describe the physical or logical arrangement of devices on a computer network. There are many ways to connect a network topology — from bus, mesh, star, and more. In short, a network topology describes how computers will be set up to facilitate communication. 

Generally, network engineers use numerous criteria to determine which topology best suits their purpose. Some of those criteria include the amount of physical space, the expected amount of nodes on the network, budgetary constraints, and more. 

Nodes and Central Devices, Explained

Hub and spoke topology can best be understood with an analogy, much like many other IT concepts. Think of it like a teacher in a classroom. The classroom itself is the network, and each student is a node. The pupils’ requests are processed and arbitrated by a teacher, who serves as the “hub” in the classroom, responding to requests.

In this case, the teacher (our classroom's hub) would be a central node. The students (the spoke nodes) relay all communication to the hub. This provides several benefits and a couple of drawbacks that we'll get into later. For now, let’s dive into the details about how hub and spoke technology actually works.

How Does Hub and Spoke Topology Work?

The way hub and spoke topology works is fairly straightforward. There are two obvious components: the hub and the spoke. 

What is a Central Hub?

In hub and spoke topology, a central hub is the decision maker for all communications within a network. It is responsible for receiving any data from a spoke node and passing it to the designated recipient. It acts as a mediator of data to ensure packets are sent securely and without risk of collision. In short, every single packet routes through the central hub. While simple, we’ll soon see why that can be a double-edged sword.

In addition to its primary duties, the central hub is also used by network administrators to monitor the environment through logging. A central hub is also used to patch the spoke nodes effectively, respond to security threats, and monitor traffic flow.

Let’s break down the basics of the central hub in simple terms:

• The central hub is a specific node on the network with unique designations.

• The hub is responsible for managing and directing all traffic.

• The hub serves as a mediator of communications.

• the hub provides a point for network administrators to configure secure settings and monitor traffic.

Next, let’s talk about the other critical component of hub and spoke topology — the spokes!

How Do Spokes Communicate with Each Other?

Spokes are the rank-and-file of the network. These are the computers that the employees use, printers, fax machines, and switches. However, it may not be clear how exactly spokes communicate with each other.

Let’s say you are emailing a colleague on the other side of your building. (Or, in the remote-working world, the other side of your VPN.) The data is sent as binary packets on the hub and spoke network. Like every other packet, it is not sent to the other spoke but to the central hub. 

The central hub extracts the destination from the packets and forwards the message to the intended recipient. Once the recipient node receives the data, it processes the information accordingly. In this example, an email is delivered. Let’s walk through more about the actual communication flow in hub and spoke.

Communication Flow in a Hub and Spoke

The communication flow in hub and spoke is completely managed by the central hub. The hub prioritizes packet transmission to ensure data collision events are mitigated. The key thing to remember about hub and spoke communication flow is that the central hub receives and forwards all communication.

Real-World Examples and Use Cases of Hub and Spoke

Since hub and spoke is such a popular topology, several real-world examples and use cases exist. There are numerous illustrative cases, but one of the best examples is air traffic control. 

Hub and Spoke Example: Air Traffic Control

Airline traffic control is a canonical example illustrating hub and spoke. Each airplane represents a node. The airport represents the network. The air traffic control tower represents the central hub. The air traffic control tower tells the planes when and where to land. This is largely based on flight patterns and feedback from the pilots themselves.

Each airplane has an invisible “connection” to the tower — i.e. a spoke. The planes may fly around but are always connected to the air traffic controller, their sole communicator. 

Between this and the teacher example, we’ve covered hub and spoke topology well. But we still haven’t really spoken about practical applications. Wide area networks (WANs) are a perfect example. 

Why Do Wide Area Networks (WANs) Tend to Be Hub and Spoke?

Wide area networks are, as you can imagine, pretty big. A WAN can have thousands of nodes on it, with more nodes getting removed and added all the time. If we were to think of this in terms of ring or mesh topology, the amount of cable needed would be massive. In a mesh, each of the thousand nodes would have to be connected to each other, and this would be impossible to maintain or troubleshoot.

Adding or removing new nodes from the WAN is easy with hub and spoke. Just add a new node, attach it to the hub, and you’re done. This is very cost-effective compared to other solutions that involve hooking your new node up to another random node. This will inevitably lead to additional and unpredictable maintenance.

Additionally, hub and spoke topology scales well. Since only the central hub directs traffic, it is the only piece of hardware you’d have to scale up.

Lastly, hub and spoke makes security a breeze. Since all packets must go through the central hub, all antivirus and malware detection can occur in one place. 

To sum it up, WANS use hub and spoke for the following reasons:

• Hub and spokes affinity for scaling

• Cost-effective

• Easy to add and remove nodes

• Easy to add security configurations

As discussed, WANs use hub and spoke topology, but what about telephone connections?

Are Telephone Connections Hub and Spoke?

Regular telephone lines, called Plain Old Telephone Service (POTS), usually use a point-to-point system to relay communication — not hub and spoke. At best, it would be a star topology. 

When you make a telephone call, the call is sent to a central office but is not managed there. No central hub is determining where it should be routed. Instead, you are connected directly to the end user. The central office is more of a central jump point than a central hub.

Modern telephone connections such as VoIP utilize hub and spoke topology. For example, a VoIP call will route calls to different recipients using central data servers.

In summary, POTS is point-to-point communication, while VoIP leverages hub and spoke topology. We’ve discussed theoretical and practical examples of hub and spoke topology. Now, let's go over how your organization could benefit from its implementation.

Main Benefits of Hub and Spoke Topology

As one of the most widely used topologies, you can bet hub and spoke technology has numerous advantages. Here’s how it can benefit your organization. 

Hub and Spoke in Networking is Straightforward

One of the greatest benefits of hub and spoke topology is its ease of use. For instance, let’s say you have a Local Area Network (LAN) with ten nodes and one central server. If you need to add an 11th one, all you need to do is set up the node and hook it into the central hub (i.e. server). Very simple.

In contrast, in a mesh topology, you would have to hook that node up to every single other node. In this case, that would be twenty connected cables. I hope you like crimping CAT 5!

Not only is it simple for connectivity, but it is simple for scaling. To scale up your network's response time, the only node that will need more horsepower is the central hub, which does all the heavy lifting.

In other topologies, the duties of network traffic management are delegated in part to each node. Hub and spoke is not only simple, but it has more bang for its buck.

Hub and Spoke Can Be Cost-Effective

Oftentimes, an organization's bottom line is significantly affected by the labor and parts required to troubleshoot hardware. 

Hub and spoke topology makes this extremely easy to figure out. If traffic is no longer getting routed, then it's because the server is down. That’s it. (This is assuming the cable is working, of course.) Granted, as the hub’s duties increase in complexity, it may not be so trivial. But at least you know where to start.

Hub and spoke topology is also cost-effective because it reduces hardware costs. For example, in a mesh topology, you need roughly double the amount of cables as you have nodes. 

For dual ring topology, you also need double the amount of cable. But for hub and spoke, you only need as many cables as you have nodes. This saves a LOT of capital on cables. 

Why Security Can Be Better on Hub and Spoke

There is a saying in IT that if you don’t have security, you don’t have anything. With hub and spoke technology, you will make your system administrator’s life much easier. That is because security configurations are far easier to manage from a centralized point. 

For instance, if an antivirus program needs to be on every node, then the central hub can be ordered to disseminate it to all of its spoke nodes. In contrast with mesh, star, or bus, the antivirus would have to be installed on each node individually. 

In addition to ease of dissemination, the central hub can serve as a firewall. It can detect different ports from the packets being sent to and fro. So, if port 8080 is supposed to be closed on Node B, it can easily check that. 

Lastly, logging is far easier on a central server. An administrator can check all network activity from the central hub, simply because all network activity travels through it.

What Are Hub and Spoke Topology Alternatives?

While hub and spoke is certainly a worthwhile topology, several alternatives exist.

Hub and Spoke vs. Mesh Topology

Mesh topology is a network environment where every node is connected to every other node. As you can imagine, that's a lot of wires. However, it has an extremely high level of fault tolerance. This differs from hub and spoke, where the whole network goes down if the central hub goes down.

Ring Topology vs. Hub and Spoke

Ring topology is another battle-tested topology connecting each computer to its two nearest neighbors. This creates a ring for data to pass in one direction. Ring topology can benefit smaller networks but relies on each node working correctly. If even one goes down, then so does the network. 

However, network failure can be prevented using dual ring topology. In this instance, the topology has a secondary ring that is in a passive state. If the primary ring loses connectivity, then it is activated.

Star Topology vs. Hub and Spoke in Networking

While people (myself included) often use star topology and hub and spoke topology interchangeably, there are subtle differences.

In star topology, the central node serves as a simple data router. It does not manage the routing at all — it acts more as a way to facilitate point-to-point communication.

On the other hand, the central hub takes a more active role in data management in a hub and spoke topology.

Hub and Spoke Topology vs. Tree Topology

Tree topology can often be considered a hybrid of star topology and bus topology. Bus topology is when each node is connected via a bus or a “backbone” that transmits data to the intended recipient. 

The tree topology is often a wise decision when certain parts of the network need to be cordoned off. For example, the software engineering department must be sequestered from the HR department. In that case, its essential multiple-star topology is connected via a bus. 

Understanding Network Topology Types: What's Next?

Knowing the pros and cons of different topology types is one of the foundational lessons any network engineer should learn early on in their career. Now that you know more about hub and spoke topology, you can make smarter decisions about when you'd want to use hub and spoke versus another topology type for your organization's needs.

Hub and spoke topology can be a simple, cost-effective solution for transmitting packets across a network. It works by using a central hub that routes and analyzes data and forwards it to the intended recipient. Hub and spoke topologies are highly regarded as secure because of how easy it is to configure security protocols and analyze packet data.

The next steps are to better understand each of the other topologies, which you will definitely need to know for your Network+ certification. As you learn about the characteristics of network topologies, make sure to cover these other fundamental networking topics:

• Open Systems Interconnection (OSI) model layers

• Types of cables and connectors

• Common ports and protocols

• Cloud concepts and connectivity

• Subnet configuration and IP addressing schemes

CBT Nuggets subscribers have access to Network+ training and resources that will help you learn these concepts and more. Start training today — the first 7 days are free.