Flags (1 byte) (BPDU)

Protocol: BPDU (Spanning Tree)

Field: flags

Length: 1 byte

Contents: topology change notification.

Indicates the contents of BPDU in case of a topology change. Specified are:

00000001 - TC - Topology Change Notification

This flag is used by a designated bridge to acknowledge a Topology Change Notification BPDU. This flag lets the root bridge recognize that a topology changed has taken place. (LSB)

10000000 - TCA - Topology Change Notification Acknowledgement

This flag tells the receiving bridge that the following topology data (contained in the current BPDU) shall be read and saved. (MSB)