Router optical mirroring

Router optical mirroring, also known as port mirroring or SPAN, duplicates network traffic from one port to another for monitoring and analysis.

What is Router Mirroring?

Router mirroring is a technique that copies network traffic from a source port to a destination port without affecting the original traffic flow. This allows network administrators to monitor, troubleshoot, and optimize network performance in real-time. It is commonly used for:

• Network monitoring: Detecting congestion, packet loss, or unusual traffic patterns.
• Troubleshooting: Identifying latency issues or misconfigured devices.
• Security and compliance: Feeding mirrored traffic into SIEM, IDS/IPS, or audit systems for analysis .

Types of Router Mirroring

1. Local SPAN: Mirrors traffic from one port to another on the same router, useful for monitoring local network issues .
2. Remote SPAN (RSPAN): Mirrors traffic from a port on one router to a port on a different router, enabling monitoring across multiple network segments .
3. Ingress/Egress Mirroring: Traffic can be mirrored incoming (ingress), outgoing (egress), or both, depending on the monitoring needs .

How It Works

• Source Port: The port whose traffic is being monitored.
• Destination Port: The port where mirrored traffic is sent, often connected to a network analyzer or monitoring device.
• Monitor Session: A configuration that defines which source ports are mirrored to which destination ports .
• Mirrored traffic does not interfere with normal network operations .

Configuration Example (TP-Link Routers)

1. Access the router's network menu and select Port Mirror.
2. Enable the Port Mirror function.
3. Choose the mirroring mode: Ingress, Egress, or Ingress & Egress.
4. Select the Mirroring Port (destination) and Mirrored Port(s) (source).
5. Save the configuration to start monitoring traffic .

Applications

• Performance Analysis: Monitor bandwidth usage and optimize Quality of Service (QoS).
• Security Monitoring: Detect suspicious activity or unauthorized access.
• Compliance: Maintain audit trails for regulatory requirements.
• Enterprise Networks: WiFi 6/6E and 5G networks benefit from port mirroring due to higher throughput and complexity .

Supported Hardware

Many modern routers, including enterprise-grade and prosumer models, support port mirroring. Examples include TP-Link AC1200 (Archer A54), TP-Link AX3000 (Archer AX55), and Cisco NCS 5500 series . Note that some models may not support this feature, so checking the router's specifications is essential . Router optical mirroring is a critical tool for network visibility, troubleshooting, and security, making it an integral part of modern network management.