Chapter 20: Stp Commands - Extreme Networks ExtremeWare XOS Command Reference Manual

ExtremeWare XOS 11.5 supports only the Summit X450 family of switches and the BlackDiamond 8800 series switch.
20 STP Commands
This chapter describes commands for:
Creating, configuring, enabling, and disabling Spanning Tree Protocol (STP) on the switch
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Enabling and disabling Rapid Spanning Tree Protocol (RSTP) on the switch
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Enabling and disabling Multiple Spanning Tree Protocol (MSTP) on the switch
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Displaying and resetting STP settings on the switch
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STP
The Spanning Tree Protocol (STP) is a bridge-based mechanism for providing fault tolerance on
networks. STP is a part of the 802.1D bridge specification defined by the IEEE Computer Society. To
explain STP in terms used by the 802.1D specification, the switch will be referred to as a bridge.
STP allows you to implement parallel paths for network traffic and ensure that redundant paths are:
Disabled when the main paths are operational.
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Enabled if the main path fails.
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NOTE
STP and Extreme Standby Router Protocol (ESRP) cannot be configured on the same Virtual LAN (VLAN)
simultaneously.
RSTP
The Rapid Spanning Tree Protocol (RSTP) IEEE 802.1w provides an enhanced spanning tree algorithm
that improves the convergence speed of bridged networks. RSTP takes advantage of point-to-point links
in the network and actively confirms that a port can safely transition to the forwarding state without
relying on any timer configurations. If a network topology change or failure occurs, RSTP rapidly
recovers network connectivity by confirming the change locally before propagating that change to other
devices across the network. For broadcast links, there is no difference in convergence time between STP
and RSTP.
RSTP supersedes legacy STP protocols, supports the existing STP parameters and configurations, and
allows for seamless interoperability with legacy STP.
MSTP
MSTP logically divides a Layer 2 network into regions. Each region has a unique identifier and contains
multiple spanning tree instances (MSTIs). An MSTI is a spanning tree domain that operates within and
is bounded by a region. MSTIs control the topology inside the regions. The Common and Internal
Spanning Tree (CIST) is a single spanning tree domain that interconnects MSTP regions. The CIST is
responsible for creating a loop-free topology by exchanging and propagating BPDUs across regions to
form a Common Spanning Tree (CST).
ExtremeWare XOS 11.5 Command Reference Guide
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