Bridge Protocol Data Units (BPDUs) are frames that
contain information about the spanning tree protocol (STP). A switch
sends BPDUs using a unique source MAC address from its origin port
to a multicast address.
There are two kinds of BPDUs for 802.1D
Spanning Tree:[
- Configuration BPDU, sent by root bridges
to provide information to all switches.
- TCN (Topology Change Notification), sent by bridges towards
the root bridge to notify changes in the topology, such as port
up or port down.