3 Roads to Network Segmentation

In this article, we’ll delve into the successful strategies we've employed with our clients, explore why network segmentation is crucial, and review the solutions that have proven effective in various environments. Let's get started by understanding what network segmentation is and why it's essential.

What is Network Segmentation?

At its core, network segmentation involves dividing a network into smaller, logical segments, typically through the use of VLANs (Virtual Local Area Networks). Imagine a default setup with a switch – be it 24-port or 48-port – where every device is part of a single VLAN (usually VLAN 1). This setup allows all devices to communicate freely with one another, which, while convenient, poses several security risks. Network segmentation, therefore, aims to create isolated segments within the network to enhance security, performance, and compliance.

The Three Main Reasons for Network Segmentation:

1. Security

One of the primary drivers for network segmentation is security. In an unsegmented network, devices can freely communicate, leading to significant East-West traffic (communication within the network). This unrestricted access can facilitate the lateral movement of threats within the network, making it easier for attackers to compromise multiple systems. By segmenting the network, we can implement firewall rules and access control lists (ACLs) at the points where these segments intersect (typically on core switches or firewalls), effectively limiting East-West traffic. Common segments include clients, servers, printers, cameras, and IoT devices, each with restricted access to one another, thereby reducing the attack surface.

2. Performance

Another critical aspect is performance. Network segmentation can significantly improve the performance of networked applications, particularly those requiring high quality of service (QoS), such as VoIP systems. By placing phones in a dedicated VLAN, we can apply QoS policies across the entire VLAN, ensuring reliable voice communication. Additionally, segmentation helps manage broadcast domains. Large networks with many devices can experience broadcast storms, where excessive broadcast traffic hampers network performance. By segmenting the network, we reduce the number of devices in each broadcast domain, minimizing the likelihood of such issues.

3. Compliance

Compliance with industry standards and regulations is another compelling reason to segment your network. For example, if you're handling payment card data, PCI DSS standards mandate stringent controls on how data is processed and stored. By isolating cardholder data environments in separate VLANs, you can limit the scope of compliance audits, reducing the complexity and cost associated with demonstrating compliance.

The Three Roads to Network Segmentation:

1. Manual Segmentation

The traditional approach to network segmentation is manual segmentation. This involves creating VLANs on core switches or firewalls and assigning devices to these VLANs manually. Each switch port is configured to associate with a specific VLAN, ensuring that devices connected to these ports are placed in the correct segment.

• Advantages: Manual segmentation is straightforward and doesn't require sophisticated equipment beyond standard-managed switches. It's a cost-effective method for small, static networks where devices don't move frequently.
• Disadvantages: This approach doesn't scale well. In dynamic environments where devices are frequently moved, manual reconfiguration can be time-consuming and error-prone. Additionally, manual segmentation inherently trusts endpoints, making it vulnerable to unauthorized access if devices are unplugged and replaced.
• Security Features: To enhance security, some enterprise switches offer port security features, such as limiting the number of MAC addresses per port and implementing sticky MAC addresses, which only allow the initially connected device to communicate. Unused ports should also be disabled to prevent unauthorized access.

2. Dynamic Segmentation

Dynamic segmentation automates the assignment of devices to VLANs based on authentication and profiling, typically managed by a Network Access Control (NAC) system.

• NAC Systems: The NAC serves as the brain of this system, interfacing with Active Directory or other identity services to authenticate devices. Common NAC solutions include Microsoft NPS, Aruba ClearPass, and Cisco ISE. These systems use protocols like RADIUS for communication with network devices and 802.1X for authenticating endpoints.
• Device Profiling: Not all devices support 802.1X. For such cases, NAC systems can use MAC authentication and profiling to identify and segment devices accurately. Advanced NAC solutions can also check device compliance (e.g., antivirus status, OS updates) before granting network access.
• Advantages: Dynamic segmentation provides granular control over network access, ensuring that devices are placed in the correct VLANs based on their identity and compliance status. This approach simplifies network management by removing the need for manual configuration changes.
• Disadvantages: Implementing dynamic segmentation requires investment in NAC systems and compatible network infrastructure. Additionally, deploying and maintaining these systems can be complex and resource-intensive.

3. Agent-Based Segmentation

Agent-based segmentation shifts the segmentation logic to the endpoint devices themselves. This method involves installing agents on devices, which then enforce segmentation policies using host-based firewalls.

• How It Works: Agents installed on devices communicate with a central management system to receive segmentation policies. These policies dictate how devices interact with each other, using host-based firewalls to enforce rules.
• Advantages: This approach provides detailed visibility into device interactions, allowing for precise control over network traffic. 
• Disadvantages: Not all devices can run agents, such as IoT devices and printers. In such cases, a hybrid approach combining agent-based and traditional network segmentation methods may be necessary.
• Common Solutions: Notable solutions in this space include Illumio and Guardicore, which offer comprehensive management dashboards and robust policy enforcement capabilities.

Conclusion

Whether you choose manual, dynamic, or agent-based segmentation depends on your specific needs, network complexity, and resources. By understanding and implementing the appropriate segmentation strategy, you can protect your network from threats, ensure reliable performance, and meet compliance requirements. If you need assistance with implementing network segmentation, our team at Matrix Networks is here to help. Reach out to us for tailored solutions that fit your unique environment. Contact Matrix Networks today.