Switched Port Analyzer (SPAN)

Switched Port Analyzer, or SPAN, is a feature commonly associated with Cisco switches for monitoring network traffic. It copies traffic from one or more source ports or VLANs to a defined destination port. An analysis device or packet capture system can be connected to this destination without directly interfering with the original traffic flow. SPAN is used for network monitoring, packet capture, performance analysis, troubleshooting and security analysis. Depending on the switch and configuration, incoming and outgoing traffic can be selectively mirrored. A related technology is Remote SPAN, or RSPAN, which enables mirrored traffic to be transported across multiple switches. SPAN helps network administrators examine communication flows in detail and investigate network performance, connectivity and security issues.