What Is Network Segmentation?

Network segmentation divides a computer network into smaller parts. This helps improve performance and security, among other benefits. You might also hear it called network segregation, network partitioning, or network isolation. 

To visualize network segmentation, think about a large office building. If each department has its own section of the network, they won't interfere with each other's work. This makes everything run smoother.

How network segmentation works

Segmentation works by controlling how traffic flows between the smaller, segmented parts. You can completely block traffic from moving between sections. Alternatively, you can limit the accessible parts of a network based on traffic type, source, destination, or even more specific criteria. This is what's known as a segmentation policy. 

Imagine a large bank with multiple branches. The bank's security policy might restrict branch employees from accessing the financial reporting system. Network segmentation would enforce this policy by keeping branch traffic away from the financial system. This not only keeps data safe but also ensures the financial system runs efficiently for analysts who need it.

In the past, we used things like internal firewalls and Access Control Lists (ACLs) to enforce segmentation policies. We also configured Virtual Local Area Networks (VLANs) on our networking equipment. However, these methods were complicated and expensive. 

Nowadays, software-defined access technology simplifies the process. It groups and tags network traffic and then uses these tags to enforce policies. This happens directly on the network equipment, but without the complexity we used to deal with.

Microsegmentation takes it a step further. It uses more detailed information, such as application-layer data, to create highly specific policies. This allows for a level of granularity and flexibility that fits the unique needs of different organizations or business applications. 

Types of network segmentation

Physical segmentation

Physical network segmentation is a practical, hands-on approach to breaking down a network into smaller, more manageable segments. You achieve this by using tangible tools—routers, wiring, switches, firewalls, and other hardware components.

Picture your entire network as a sprawling open space, like a large, open-plan office. Physical segmentation is like constructing walls and doors within that space, creating distinct rooms or sections. Each section can be monitored and controlled individually, making it easier to manage and secure. 

Think of physical segmentation as the brick-and-mortar foundation of your network's security house. Each segment is a well-defined space, providing a robust barrier against unauthorized access and helping keep your network safe and sound.

In a corporate environment, you might have separate segments for different departments. The finance department might have its own isolated network segment, accessible only by finance staff. This ensures that sensitive financial data is kept secure and separate from the network traffic of, say, the marketing department.

Managing a physically segmented network can be straightforward because you have a clear overview of where each piece of hardware is located. For instance, if a device on the network starts acting up, you can physically check and isolate the issue without it affecting other segments.

However, physical segmentation isn't just about plugging in hardware and calling it a day. You need to ensure there's sufficient equipment to maintain these isolated segments, which can be a substantial investment. But the trade-off is clear: improved security, better control, and easier management of network resources.

Logical segmentation

Logical segmentation organizes and secures your network without changing the physical layout. You use software and configuration settings to create virtual networks within the same physical network. 

This type of segmentation helps you manage traffic efficiently and enhance security by isolating different types of network traffic. It gives you the flexibility to create secure, efficient, and manageable network environments using software configurations.

One of the common methods used for logical segmentation is VLANs or Virtual Local Area Networks. If you have a large office with several departments like HR, Sales, and IT, you can create separate VLANs for each department. 

That will keep the network traffic from each department isolated, which is great for both performance and security. The HR team’s sensitive data stays within their VLAN, while the IT team can manage infrastructure without interference.

Another example is the use of VPNs or Virtual Private Networks. Imagine you have remote employees who need to access corporate resources securely. You can set up a VPN to segment their traffic from the public internet. This ensures that their connection to the office network is encrypted and secure, even if they’re working from a coffee shop or at home.

You can also deploy software-defined networking (SDN) for more advanced logical segmentation. SDN allows you to programmatically control the network, making it flexible and adaptable. 

For instance, if you have a web server that needs to handle traffic from different user groups, you can use SDN to dynamically allocate network resources. This approach helps you efficiently manage bandwidth and enhance user experience without physically changing the network infrastructure.

Logical segmentation is particularly useful in scenarios where you need to create multi-tenant environments. Let’s say you are a cloud service provider hosting services for multiple clients. 

Using logical segmentation, you can create isolated virtual networks for each client within the same physical infrastructure. This guarantees that one client’s traffic doesn’t interfere with another’s, ensuring privacy and security.

Micro-segmentation

Micro-segmentation takes network segmentation to the next level by creating highly granular zones in your network. It splits your network into tiny, more manageable pieces.

One of the best attributes of micro-segmentation is its precision. Imagine you have a data center with hundreds of servers. Instead of just grouping these servers into a few large segments, micro-segmentation lets you control the communication between individual servers or small groups of servers. 

This means, for example, that a web server can only talk to an application server, not directly to a database server unless it's explicitly allowed. It’s like building tiny, secure “rooms” within the larger “house” of your network. If a hacker somehow gets into your system, moving laterally would be incredibly difficult because each segment has strict access controls.

A good application scenario of micro-segmentation is with virtual environments. In a virtualized data center, you might have virtual machines (VMs) running various applications. With traditional segmentation, if one VM gets compromised, it could potentially affect others on the same network. 

With micro-segmentation, however, each VM can be isolated, reducing the blast radius if something goes wrong. It’s like having fire doors between each room in a building – a fire in one room won't easily spread to others.

Micro-segmentation also shines when it comes to compliance. Different segments can enforce different policies based on regulatory requirements. For instance, healthcare organizations must comply with HIPAA. 

By using micro-segmentation, the organization can create segments that meet HIPAA standards while keeping unrelated parts of the network separate. This targeted approach makes audits and compliance checks much easier.

Benefits of segmenting enterprise networks

Improves network security

Network segmentation slows down or even stops attackers from moving freely within a network. If a malicious actor breaches your network defenses and gets into one segment of the network, they can't automatically access and take down the entire network. This helps secure the network.

Consider your employees' workstations. If you segment them from the critical infrastructure, an infected laptop won't compromise your servers. Any malware on a user's machine would be contained, reducing the risk to other parts of the network. 

Another real scenario is guest Wi-Fi. By segmenting it from the main corporate network, you ensure that visitors can't access sensitive resources. Guests get their own isolated segment with limited access, which protects our internal systems.

Virtual Local Area Networks (VLANs) are often used to achieve this level of segmentation. In a standard corporate setup, you could have VLANs for different departments like HR, Finance, and R&D. This approach limits who can interact with whom, based on their job roles.

With proper network segmentation, you can also implement more focused security policies. For example, the Finance VLAN might have stricter monitoring and logging compared to the Sales VLAN. This helps you catch any suspicious behavior early, tailored to the segment's specific needs.

Isolates sensitive data

Network segmentation helps to isolate sensitive data, essentially creating a fortress within your network. This ensures that only authorized personnel can access the most crucial information. 

For example, you could segment the network so that employees handling payroll only have access to relevant payroll systems and data. This prevents anyone outside that specific segment from even seeing the data, let alone tampering with it.

Network segmentation isn't just about keeping the bad actors out; it's also about reducing the impact if they get in. Imagine an attacker breaches your network through a less critical section, like a public-facing web server. If your financial records are in a separate, isolated segment, the attacker can't simply waltz over to that sensitive area.

Streamlines network traffic management

Splitting up your network into different segments enables you to control the flow of information more effectively. It allows you to create a tunnel for critical applications so you can prioritize its traffic, ensuring it gets the bandwidth it needs. 

Troubleshooting becomes less challenging with a segmented network. If there’s an issue in the system, you know exactly where to look. For example, if your email server is acting up you don’t have to sift through the whole network to pinpoint the problem.

Bandwidth management is another perk of network segmentation. You can allocate more resources to segments that need it the most. For example, if your video conferencing tools are crucial, you might place them in a dedicated segment with ample bandwidth. This prevents a situation where a big file download in another segment chokes the video quality for everyone.

Network segmentation allows you to apply specific policies per segment too. This granularity means you can fine-tune rules based on the needs of each group. Suppose you need stricter security policies for the accounting team. By segmenting their part of the network, you can enforce tighter controls without impacting other users.

Reduces congestion

Segmentation reduces network congestion by isolating traffic into smaller, manageable parts. Without it, all your devices would share the same network. This can cause slowdowns, especially during peak usage times. 

By creating separate network segments, you ensure that less critical devices don't interfere with critical ones. Your essential services can operate smoothly without having to compete with someone streaming videos in the canteen. 

You can also segment the corporate network to separate employee workstations from the guest Wi-Fi network. This way, guests can browse the internet without affecting the company's core business applications. Segmentation provides the structure needed to keep network traffic under control, ensuring each segment gets the performance it requires.

Simplifies compliance

Navigating the maze of regulatory compliance is tough. However, network segmentation makes it simpler. By dividing a network into smaller, manageable parts, you can easily apply targeted security measures. 

For example, think of segmenting an office network to separate the workstations from the financial systems. This way, only authorized personnel can access sensitive financial data, making both security and audits more streamlined.

When dealing with PCI DSS (Payment Card Industry Data Security Standard) compliance, segmentation is a lifesaver. Financial services companies can isolate cardholder data environments from the rest of the network, reducing the number of systems that need to comply. This minimizes risk and makes audits quicker and less painful. 

With GDPR (General Data Protection Regulation), segmentation helps protect personal data and control access. For instance, you can segment customer service areas from marketing departments. This control ensures that personal data is only handled where it's needed, minimizing data breach risks and simplifying GDPR compliance checks.

Continuous monitoring is crucial. By segmenting the network, you enhance visibility and control. For example, using firewalls and IDS/IPS (Intrusion Detection and Prevention Systems) within each segment helps monitor traffic and identify any anomalies.

Network segmentation also aids in compliance by logging and tracking access. Detailed records of who accessed what and when are automatically generated. If there’s a breach, it’s easier and faster to pinpoint the vulnerability. This thorough approach not only satisfies compliance regulations but also bolsters overall network security.

How to implement network segmentation at the enterprise level

Identify and classify your assets

Think about what's critical, what's sensitive, and what's routine. For example, your finance department's servers shouldn't be on the same network segment as the coffee machine or office printers. These classifications will guide your segmentation strategy.

Set up VLANs

VLANs are like the dividers in a big warehouse. They help separate different types of traffic. Say you've got a department handling customer data and another one handling internal communication. 

You don't want cross-talk between these departments because it could lead to data breaches. By assigning each department its own VLAN, you create a secure bubble around their communications.

Firewalls come into play here too. Picture them as security guards stationed at the entrances and exits of each VLAN. They enforce policies about which data can travel where. So, if someone from the marketing department tries to access the HR files, the firewall steps in and blocks it unless it's explicitly allowed.

Establish tight access controls

Network segmentation requires tight access controls. Use role-based access control (RBAC) to simplify this. For instance, only IT staff should have access to network infrastructure components, whereas sales staff only need access to CRM tools. By narrowing down who can access what, you reduce the risk of insider threats and accidental breaches.

Set up physical subnetwork boundaries

In some cases, it makes sense to have separate physical networks for extremely sensitive operations. For example, a lab working on a top-secret project might be completely isolated from the corporate network. 

This is not just about plugging cables differently, but also about setting up distinct hardware like routers and switches.

Configure network monitoring tools

Implementing a solid network monitoring system will alert you to unusual activity. For example, if there's a spike in traffic on a segment that usually has low activity, it could be a sign of a problem. Tools like intrusion detection systems (IDS) and intrusion prevention systems (IPS) can be invaluable here.

Draw up a network audit schedule

Don't overlook the importance of regular audits. You need to check if your segmentation is effective and up-to-date. Network configurations can drift over time, especially in a growing company. Policies that made sense a year ago might need tweaking today. Regular audits help you stay on top of this.

Implementing network segmentation might seem daunting at first, but it pays off in the long run. It’s all about creating smaller, manageable, and secure zones within your larger network. By taking these steps, you help ensure your corporate network is both safe and efficient.