Designated bridge and designated port

The designated bridge:

• For a device: Device directly connected with the local device and responsible for forwarding BPDUs to the local device.
• For a LAN: Device responsible for forwarding BPDUs to this LAN segment.

The designated port:

• For a device: Port through which the designated bridge forwards BPDUs to this device.
• For a LAN: Port through which the designated bridge forwards BPDUs to this LAN segment.

In the following topology, Device B and Device C are directly connected to a LAN.

If Device A forwards BPDUs to Device B through port A1, the designated bridge and designated port are as follows:

• The designated bridge for Device B is Device A.
• The designated port of Device B is port A1 on Device A.

If Device B forwards BPDUs to the LAN, the designated bridge and designated port are as follows:

• The designated bridge for the LAN is Device B.
• The designated port for the LAN is port B2 on Device B.