What is network segmentation: a complete guide

How does network segmentation work?

The network’s division into segments allows it to manage each of them individually. Network traffic protocols can supervise what connections and content are allowed. Security protocols can also be applied for each subnetwork to manage overall security rules better.

Network segments frequently have dedicated hardware to minimize touching points between them. Network configurations usually define interconnectivity between them, branching network segmentation into its two types.

Physical segmentation

As you can guess from its name, physical segmentation uses dedicated hardware to set up closed-off networks. This makes it one of the most difficult and costly network segmentation approaches. Each network segment requires separate internet connections, physical hardware, and a firewall.

This approach is sometimes called perimeter-based segmentation, and everything else outside the network perimeter is considered untrustworthy. The problem is that once hackers penetrate such networks, they don’t have any capabilities to protect themselves. There is no internal filtering, so every user can access everything on the network by default. What made the situation even worse was that due to the amount of currently used endpoints, it was very hard to inspect each connecting device thoroughly.

Virtual segmentation

The modern workplace has so many endpoints that it’s almost impossible to pinpoint where the perimeter ends. Therefore, virtual segmentation aims to extend beyond the perimeter. Switches manage virtual local area networks, and the firewalls are deployed to oversee the whole network independently of physical infrastructure.

Essentially, this flips the idea of the perimeter on its head, and segmentation is something that allows the creation of numerous virtual structures for easier supervision. It has the same benefits as the physical approach but in a distributed model that isn’t susceptible to flaws. This approach is also cheaper and allows adjusting security policies within each segment.

Why do businesses need network segmentation?

IT infrastructure security is one of the key assets for modern organizations. Network segmentation is a good way to achieve this and reduce cybersecurity expenses. Perimeter-based segmentation plans are being phased out in favor of more modern solutions that better respond to current business needs.

Network segmentation enforces security policies and helps create boundaries between teams to prevent data spills. It also helps distribute network traffic, increasing performance more evenly.

Network segmentation use cases

Network segmentation can help organizations in several ways. Below are a few use cases of how businesses use network segmentation to enhance security.

Guest Wi-Fi: A company can offer Wi-Fi to visitors and contractors with low risk. When guests log in, they only get access to the internet, not the main network.

User group access: Companies can separate departments into their own networks. This limits access to only those who need it. For example, if someone from the marketing team tried to access the accounting resources, there would be an alert.

Public cloud security: Cloud providers secure the infrastructure, but customers are accountable for their own data, systems, and apps. Segmenting cloud environments can keep applications and data separate and secure.

PCI DSS compliance: Credit card data can be placed in a secure zone with strict rules. Only necessary traffic is allowed, and everything else is blocked. This is often done with virtual firewalls for PCI DSS compliance.

Benefits of network segmentation

Better administrative controls are undeniably one of the greatest appeals of network segmentation. However, this isn’t the only advantage that this approach brings.

• Network isolation. Creating boundaries between different sub-segments increases security, obstructing lateral movement for hackers once they breach the network. With such movement restrictions, it’s also much easier to mitigate threats.
• Strict access control. Subsegment rules can be applied to close off particular network areas, only allowing access to those with clearance.
• In-depth monitoring. Due to their smaller scope, detecting a threat in a subnet is much easier than in a larger network.
• Higher performance. A network’s size can negatively affect its performance. Smaller subnets can be more effective, and it will be easier to balance their load. One segment won’t throttle another segment’s traffic allowing fluid business operations free of network congestion.
• Helps to meet compliance requirements. Most regulatory frameworks require administrators to ensure data is inaccessible to unauthorized users. Successful adoption of network segmentation can contribute to your organization’s compliance.
• Safer network and endpoints. A secure network means that threats can’t easily spread to endpoints. The opposite is true—the whole network can’t get infected as it’s limited only to the endpoint.

Challenges of network segmentation

While the benefits of network segmentation are undeniable, preparation and implementation can be challenging. Several barriers should be considered when implementing it in your business.

Oversegmentation

While smaller networks are easier to manage and secure, this should be done reasonably. It’s easy to go too far and begin micro-segmenting your network, which takes time to implement without achieving meaningful results. Good strategic insight can be invaluable here to balance out how small segments should be beneficial rather than detrimental.

Resource mismanagement

Restructuring the whole network is a serious undertaking in an enterprise. Therefore, it’s important to prepare beforehand to see whether there will be enough personnel to make it happen, not to mention the needed skills and other business projects and ventures where they may also be needed. Poor planning can lead to huge setbacks and threaten the project’s success.

Treating network segmentation as a finished project

Cybersecurity shouldn’t be treated as something that’s already taken care of and can be crossed off the list. The same applies to network segmentation. Even after finalizing network segmentation, it should be periodically audited. The reason is that cybersecurity threats constantly change, and your security needs to be improved to better secure against them.

Types of network segmentation

There are many network segmentation solutions available. Here are the most common ones you might come across.

VLAN network segmentation

Virtual local area networks (VLANs) create smaller network segments using IP addresses for partitioning. This method achieves everything expected from network segmentation and protects against threats spreading from VLANs to VLANs. However, it entails managing an access control list to track which devices can access it.

Firewall segmentation

Instead of relying on virtual networks, you can deploy firewalls carving out particular zones. This can block internal communications between them, which helps to limit the spread if the network becomes infected. However, depending on your organization’s size, you may need hundreds of firewalls implemented. Due to its scope, it’s easy to miss important details and introduce considerable complexity to the system.

SDN-based segmentation

Software-defined networking (SDN) uses centralized controllers abstracted from the network’s physical hardware. Its main benefit is that it supports greater segmented network automation and programmability, so it’s possible to set them to do exactly what you need. However, the most frequent use case for those is network security policies implementation rather than security visibility into workflows.

Host-based segmentation

This method relies on special software installed on endpoints to report data back to a central location. It uses technologies like workload telemetry and visualizations to paint a map of multi-cloud environments that humans can easily control from a central dashboard.

Micro-segmentation

This approach uses firewalls deployed in the data center to segment the network by blocking all traffic except for what is allowed. That way, the workloads are divided by applying predefined rules to each unique segment.

Zero Trust & network segmentation

Network segmentation is very useful when paving the way for the Zero Trust approach, where implicit trust is eliminated from the IT infrastructure. In this framework, trust has to be earned through verification.

This helps to address the flaws in previous network cybersecurity models, which assumed their perimeter was secure. Therefore, access to Zero Trust is a privilege, and it’s granted only on a case-by-case basis.

Network segmentation is a perfect fit as network division can help to introduce tighter controls for important assets. User access permissions can be configured for each subnetwork, creating barriers to enforcing Zero Trust across the network infrastructure.

In this framework, users aren’t allowed to roam the internal network, and data is freely provided only on a ‘need to know basis. This protects from insider and external threats and reduces the attack surface the hackers could use.