Technical data

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CHAPTER 5
Spanning Tree Group
When multiple paths exist on a network, Spanning Tree Group (STG) configures the network so
that a switch uses only the most efficient path. The following topics are discussed in this chapter:
 “STG Overview” on page 73
 “Bridge Protocol Data Units (BPDUs)” on page 74
 “Multiple Spanning Trees” on page 78
 “Multiple Spanning Tree Group Protocol” on page 81
 “Port Fast Forwarding” on page 84
 “Fast Uplink Convergence” on page 84
 “Hot Links” on page 85
STG Overview
Spanning Tree Group (STG) detects and eliminates logical loops in a bridged or switched network.
When multiple paths exist, Spanning Tree configures the network so that a switch uses only the
most efficient path. If that path fails, Spanning Tree automatically sets up another active path on the
network to sustain network operations.
The RackSwitch G8000 (G8000) supports IEEE 802.1D Spanning Tree Protocol. It is compatible
with PVST+ by configuring each STP Group in different STP instances.
Note – The G8000 also supports IEEE 802.1w Rapid Spanning Tree Protocol, and IEEE 802.1s
Multiple Spanning Tree Protocol. For more information, see Chapter 6, “Rapid Spanning Tree
Protocol/Multiple Spanning Tree Protocol.”