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bridge protocol data unit (BPDU)

The Bridge Protocol Data Unit (BPDU) is a protocol data unit for bridges or switches that uses the spanning tree protocol

to exchange management information and control information between the bridges of a network. To determine the network topology and the location of bridges in the network, root bridges exchange BPDU frames with each other. Such a BPDU frame consists of several data fields


Bridge Protocol Data Unit (BPDU) frame

Bridge Protocol Data Unit (BPDU) frame

The first data field contains the destination address of the root bridge as seen by the sending bridge. This address field is followed by the Source Address (SA) data field, which is the address of the sending bridge and its port designation. The other data fields are the Length field, which is the length of the BPDU frame, and the Destination Service Access Point (DSAP) and Source Service Access Point (SSAP) data fields. The service access point data fields are individual destination and source addresses or a merged group address of a MAC address

. Completingthe Bridge Protocol Data Unit (BPDU) are the configuration messages containing important identifiers for the corresponding route segment.

Bridge Protocol Data Units are typically sent every two seconds. Receiving bridges use the configuration messages contained in the BPDUs to optimize routing

. Theyalso transmit this data to the connected local area networks (LAN).

Bridge Protocol Data Units (BPDU) are used for loop suppression in the network and to improve data traffic. If the protocol data units do not reach the communication partner, then there is a fault or interruption in the frequently used connection. The new path selection is then executed via the spanning tree protocol.

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Englisch: bridge protocol data unit - BPDU
Updated at: 05.05.2020
#Words: 415
Translations: DE