H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 159)

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MSTP Configuration
The term switch in this document refers to a switch in a generic sense or an access controller
configured with the switching function unless otherwise specified.
When configuring MSTP, go to these sections for information you are interested in:
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MSTP Overview
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Configuring the Root Bridge
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Configuring Leaf Nodes
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Performing mCheck
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Configuring Protection Functions
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Displaying and Maintaining MSTP
MSTP Overview
Introduction to STP
Why STP?
The Spanning Tree Protocol (STP) was established based on the 802.1d standard of IEEE to eliminate
physical loops at the data link layer in a local area network (LAN). Devices running this protocol detect
loops in the network by exchanging information with one another and eliminate loops by selectively
blocking certain ports until the loop structure is pruned into a loop-free network structure. This avoids
proliferation and infinite recycling of packets that would occur in a loop network and prevents
deterioration of the packet processing capability of network devices caused by duplicate packets
received.
In the narrow sense, STP refers to the STP protocol defined in IEEE 802.1d; in the broad sense, it refers
to the STP protocol defined in IEEE 802.1d and various enhanced spanning tree protocols derived from
the STP protocol.
Protocol Packets of STP
STP uses bridge protocol data units (BPDUs), also known as configuration messages, as its protocol
packets.
STP identifies the network topology by transmitting BPDUs between STP-compliant network devices.
BPDUs contain sufficient information for the network devices to complete the spanning tree calculation.
In STP, BPDUs come in two types:
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Configuration BPDUs, used for calculating spanning trees and maintaining the spanning tree
topology.