Chapter 5 Configuring Spanning Tree Parameters; In This Chapter - Alcatel OmniSwitch 6800 Series Network Configuration Manual

5 Configuring Spanning Tree
The Spanning Tree Algorithm and Protocol (STP) is a self-configuring algorithm that maintains a loop-
free topology while providing data path redundancy and network scalability. Based on the IEEE 802.1D
standard, the Alcatel STP implementation distributes the Spanning Tree load between the primary
management switch in the stack and the other switches in the stack. This ensures a Spanning Tree that
continues to respond to STP Bridge Protocol Data Units (BPDU) received on switch ports and port link up
and down states in the event of a management fail over to a backup management switch. In addition, the
Alcatel distributed implementation incorporates the following Spanning Tree features:
Configures a physical topology into a single Spanning Tree to ensure that there is only one data path
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between any two switches.
Supports fault tolerance within the network topology. The Spanning Tree is reconfigured in the event
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of a data path or bridge failure or when a new switch is added to the topology.
Supports two Spanning Tree operating modes; flat (single STP instance per switch) and 1x1 (single
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STP instance per VLAN).
Supports two Spanning Tree Algorithms; 802.1D (standard) and 802.1w (rapid reconfiguration).
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Allows 802.1Q tagged ports and link aggregate logical ports to participate in the calculation of the STP
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topology.
The Distributed Spanning Tree software is active on all switches by default. As a result, a loop-free
network topology is automatically calculated based on default Spanning Tree switch, VLAN, and port
parameter values. It is only necessary to configure Spanning Tree parameters to change how the topology
is calculated and maintained.

In This Chapter

This chapter describes how Spanning Tree works and how to configure Spanning Tree parameters through
the Command Line Interface (CLI). CLI commands are used in the configuration examples; for more
details about the syntax of commands, see the OmniSwitch CLI Reference Guide.
Configuration procedures described in this chapter include:
Selecting the switch Spanning Tree operating mode (flat or 1x1) on
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Configuring Spanning Tree bridge (VLAN) parameters on
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Configuring Spanning Tree port parameters on
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Configuring an example Spanning Tree topology on
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OmniSwitch 6800 Series Network Configuration Guide
Parameters
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page 5-10.
page 5-15.
page 5-21
November 2004
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