When it comes to network traffic analysis, Westermo devices offer powerful features to help you monitor and troubleshoot your network effectively. Whether you’re diagnosing issues or implementing Intrusion Detection Systems (IDS), understanding the difference between Port Mirroring and Port Monitoring is essential.

What is Port Mirroring?

Port mirroring is a network feature that copies traffic from one or more switch ports to another port so that the data can be analyzed without interrupting the live network. Port Mirroring is available on the SandCat-3000 series and is configured via DIP switches. With this setup, all ingress (incoming) and egress (outgoing) traffic from ports 2–5 is duplicated and sent to Ethernet port 1.

Key benefits of Port Mirroring:

• Ideal for network troubleshooting
• Perfect for small, low-powered devices like SandCat-3000
• Simple to deploy between two points for full traffic visibility
  
  

Limitations:

• Not suitable for IDS
• Can be prone to packet loss, which may result in missing critical data
  
  

What Is Port Monitoring?

Port monitoring is the process of observing and tracking network ports to ensure services are running correctly, efficiently, and securely. Port Monitoring is available on WeOS-enabled devices and configured through the WeOS interface. This feature allows you to define specific ingress and egress traffic on any port and forward it to a designated destination port.

Advantages of Port Monitoring:

• Highly configurable for IDS applications
• Isolates the destination port from the network, ensuring accurate traffic capture
• Reduces packet loss thanks to dedicated hardware and software
  
  

Secure IDS Traffic Monitoring
When it comes to IDS, a more powerful and highly configurable device is required, such as the Lynx 3000 series or other WeOS-supported devices. Port Monitoring enables users to define and capture traffic flowing in and out of specific ports, providing precise control over what is monitored.

This approach effectively isolates the destination port from the rest of the network, ensuring that no traffic leaves the destination port. This isolation is critical for IDS systems because it guarantees accurate traffic analysis and allows monitoring of specific ports without interference.

Another key difference between Port Mirroring and Port Monitoring is the risk of packet loss. Port Mirroring can be prone to packet loss, which means the packet you need might be the one that gets dropped. Port Monitoring, on the other hand, leverages advanced configuration options and dedicated hardware and software to significantly reduce this risk - making it the preferred choice for IDS solutions.

Bandwidth Considerations

One important factor for both Port Monitoring and Port Mirroring is bandwidth. The combined ingress and egress traffic cannot exceed the maximum capacity of the destination port. In practical terms, if you monitor two ports consuming 60 Mbps each and the destination port supports only 100 Mbps, you will not be able to capture all traffic.

This is why careful network design is essential when implementing either method. If your bandwidth requirements exceed the destination port’s capacity, consider using a device with higher-speed ports to avoid data loss.

Which solution is right for you?

• Use Port Mirroring for basic troubleshooting and Port Monitoring for complex, security-focused network designs.
• Always design your network with bandwidth in mind. If necessary, choose devices with higher-capacity ports.
• Port Monitoring minimizes packet loss compared to Port Mirroring, making it better for critical monitoring tasks.