What Is a Flat Network? Definition, Benefits, and How It Works

Enterprise Networking Planet content and product recommendations are editorially independent. We may make money when you click on links to our partners. Learn More.

A flat network is a type of network architecture where all the devices in the data center can reach each other without having to go through intermediary devices like routers. 

In a flat network, all devices are linked to a single switch, meaning that all the workstations connected to the flat network are part of the same network segment. Since all devices are connected to a single switch, it becomes one of the easiest network designs to manage. It is also very cost-effective. 

Intermediate System to Intermediate System (IS-IS), Interior Gateway Routing Protocol (IGRP), and Routing Information Protocol (RIP) are some examples of flat network routing protocols.

What is a flat network and how do they work?

Flat networks are network architectures where all devices are connected to a single network segment without any hierarchy or central control. In a flat network, all devices are connected to a single switch or hub in the same broadcast area and communicate with each other without any intermediaries. These connected devices are considered peers with the same level of access.

Unlike a hierarchical network, where devices are segmented by intermediary hardware like routers, in a flat network, there is no hierarchy or division of a network into layers. When one connected device (A) sends a communication to another device (B), then all ports (we’ll call them X, Y, and Z) connected to the switch forward the exact same broadcast message—except the one that received the broadcast, in this case, device B. Ports X and Y may not need that information, yet they waste precious bandwidth in forwarding the message regardless. This happens because there is no logical segmentation, which restricts the traffic to non-designated devices.

Since there’s no central control, it can be difficult to isolate and manage networks in case of a security breach. Therefore, a flat network topology is ideal for small businesses that don’t have complicated requirements or don’t want to invest a ton in setting up complex networks.

Benefits of flat networks

Partially due to their simplicity, flat networks have a number of advantages, including their inexpensiveness, low learning curve, and speed of data transfer.

Cheap to set up

One benefit of flat networks is how cheap they are to set up. That’s because there’s no need for multiple routers and switches, as everything is connected back to a single switch, with low-cost hubs providing additional connectivity where necessary. In addition, since flat networks don’t require complex routing information, specialized design, or training, they significantly reduce internal IT costs.

Easy to set up

When compared to mesh or star topologies, flat networks are simple and easy to set up. Because of this simplicity, it’s very easy to design a flat network. Not a lot of thought has to go into architecting it, so it’s easy to build, easy to operate (when it’s working properly, that is) and easy and cheap to maintain.

Faster data flow

Since flat networks are made up of a single connection between nodes, they allow for faster data transmission as there is no need to route information through various gateways or hub-and-spoke systems.

Flat network issues and drawbacks

Although flat networks are cheap and easy to set up in any environment, several drawbacks in its architecture cannot be ignored, including their lack of redundancy, difficulty troubleshooting, and vulnerability to lateral attacks.

Lack of redundancy

The simplicity of a flat network also comes at a cost: dependence on a single switch. The risk in a flat network is that if the key switch fails, the whole network could come to a grinding standstill since there’s no alternative network path. This shortcoming makes flat networks limited in terms of practical scalability.

Problem in troubleshooting

Ironically, the simplicity of the design of a flat network also means that troubleshooting can be much harder. When a network problem occurs, it could be almost anywhere on the network, so finding the root cause of the problem can be difficult and time-consuming. By contrast, on a segmented network, it can be easier to isolate the location of the problem, and even if major infrastructure needs to be replaced, the problem can be isolated to the network segment hosting that infrastructure.

More prone to lateral attacks

Using a flat network leaves you more prone to lateral attacks, which allow attackers to gain access to the network through an entry point and then spread throughout the compromised network without opposition. For example, if your organization uses a flat network and malware somehow infects one of your devices, it can quickly move laterally to infect other devices on the network until the entire network is infected.

Easy for hackers to hide

When hackers succeed in penetrating the network perimeter and gain access to a corporate network, they often attempt to remain undetected on the network while at the same time performing scans and other network reconnaissance moves. This lets them navigate around the network to find the most valuable assets they can plunder.

On a large flat network, it’s much easier for a hacker to remain undetected. That’s because with so many devices and applications communicating with each other—from IP phones to desktops to print servers to security cameras—it’s much harder for security systems to analyze data flows and spot anomalous traffic that might be the tell-tale signs of hackers at work.

Who should use a flat network?

Flat networks are ideal for home user networks, mobile broadband operators, and small businesses primarily because of the cost savings associated with flat architecture over more complex systems. They’re easy to set up and don’t require costly hardware or complicated software to communicate with each other. Flat networks are also convenient for organizations with employees spread in different locations since they simplify the process of sharing resources through connected devices.

On the other hand, it’s not feasible to use flat networks in big organizations with a large number of users, as they send the same broadcast messages to every port in the broadcast domain, resulting in a lot of “noise.” For instance, consider an organization where thousands of devices talk to each other using a flat network. Apart from the inherent security risk of sensitive data being shared with everyone in the network, the problem is that all switches and hosts in the broadcast domain receive the same traffic. This results in a lot of unnecessary traffic and creates a chaotic situation.

Flat network alternatives

Flat networks make it relatively easy for threat actors to access the entire network through a single entry point and quickly transmit malicious payloads throughout the system. In such a scenario, ransomware doesn’t take long to spread through the system, leaving flat networks vulnerable to widespread and pervasive cyberattacks. 

A way out is to adopt a comprehensive defense-in-depth (DiD) strategy that helps protect your networks from cyberattacks. Network segmentation is a crucial part of a DiD security approach.

Network segmentation

Network segmentation is the process of splitting a network into smaller networks or subnets. Barriers are placed between the subnets, thus preventing interactions between them. With each subnet working as an independent unit, it prevents lateral movement and makes it difficult for malicious actors to take over the entire system. Therefore, one of the biggest benefits of network segmentation is that it improves security. Additionally, even if there is an attack, network segmentation isolates the attack to only that particular network, thereby preventing its spread to the rest of the network.

Featured IT Software

Bottom line: Is a flat network right for your business?

Ultimately, the decision to run a flat network or a segmented one is a matter for each individual organization, and the decision will always be impacted by what currently exists. A flat network may well be simpler and cheaper to set up, but if an organization already has a more complex network, then there’s likely no reason to change it back.

The bottom line is that while flat networks may be simpler and more cost-effective, segmented networks offer better security. It’s up to each organization to decide which of those is most important.

Need help managing your network? Here are the best Network-as-a-Service (NaaS) providers to help keep your network running without having to maintain your own infrastructure.

Susnigdha Tripathy
Susnigdha Tripathy
Susnigdha Tripathy is a full-time writer and editor based in Singapore, and a regular contributor to Enterprise Networking Planet. She has over 10 years of experience writing, editing, and delivering exceptional content for a variety of international technology brands such as Virtasant, a cloud technology company, and Krista Software, a provider of intelligent automation solutions. She has also appeared in ServerWatch and other industry publications.

Get the Free Newsletter!

Subscribe to Daily Tech Insider for top news, trends, and analysis.

Latest Articles

Follow Us On Social Media

Explore More