Cisco Certified Network Professional 2025 – 400 Free Practice Questions to Pass the Exam

In a Switched Port Analyzer (SPAN) configuration, spanning tree protocol (STP) must be disabled on destination ports to prevent any potential issues with network loops and unnecessary processing of the mirrored traffic.

When a SPAN session is set up, traffic from the source interfaces is copied to the destination port, where it can be analyzed by a network monitoring device. If STP were to be enabled on the destination port, it could cause the port to participate in the spanning tree calculations, leading to the port being put in a blocking state. This would prevent the monitoring device from receiving the mirrored traffic effectively, defeating the purpose of the SPAN configuration.

Disabling STP on destination ports ensures that they can always forward the mirrored traffic without interference, allowing for clear and uninterrupted analysis of the network traffic flowing through the source ports. Maintaining this configuration is crucial for effective network monitoring and troubleshooting.