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About Spanning Tree protocol topology change detection

Change detection enables the detection of topology changes and sends a topology change notification (TCN) to the Root on a per port basis. Change detection is enabled by default. When change detection is enabled and a topology change occurs, a trap is sent containing the following information so that you can identify the device:

• the MAC address of the STG sending the TCN
• the port number
• the STG ID

You can disable change detection on ports where a single end station is connected, and where powering that end station on and off would trigger the TCN. Change detection is referenced in IEEE STD 802.1D.

• About Spanning Tree protocol (STP)
• About spanning tree groups
• Understanding STGs and VLANs
• Topology change detection configuration rules
• Creating an STG