Operation Manual – MSTP
H3C S9500 Series Routing 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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MSTP Overview
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Configuration Task List
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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 the VLAN Ignore Feature
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Configuring Digest Snooping
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Configuring No Agreement Check
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Configuring Protection Functions
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Displaying and Maintaining MSTP
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MSTP Configuration Examples
1.1 MSTP Overview
1.1.1 Introduction to STP
I. Functions of 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 device performance 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) for exchanging information. BPDU is also
known as configuration packets or configuration messages.
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 computing.
In STP, BPDUs come in two types: