Operation Manual – MSTP
H3C S3610&S5510 Series Ethernet Switches
Chapter 1 MSTP Configuration
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Chapter 1 MSTP Configuration
When configuring MSTP, go to these sections for information you are interested in:
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Configuring Protection Functions
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Displaying and Maintaining MSTP
1.1 MSTP Overview
1.1.1 Introduction to STP
I. 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.
II. 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.
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Topology change notification (TCN) BPDUs, used for notifying concerned devices
of network topology changes, if any.
