Administrator Guide
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Spanning Tree Protocol (STP)
The spanning tree protocol (STP) is supported on the MXL switch platform.
Protocol Overview
STP is a Layer 2 protocol — specied by IEEE 802.1d — that eliminates loops in a bridged topology by enabling only a single path
through the network.
By eliminating loops, the protocol improves scalability in a large network and allows you to implement redundant paths, which can be
activated after the failure of active paths. Layer 2 loops, which can occur in a network due to poor network design and without
enabling protocols like xSTP, can cause unnecessarily high switch CPU utilization and memory consumption.
The Dell Networking OS supports three other variations of spanning tree, as shown in the following table.
Table 66. Dell Networking OS Supported Spanning Tree Protocols
Dell Networking Term IEEE Specication
Spanning Tree Protocol (STP) 802.1d
Rapid Spanning Tree Protocol (RSTP) 802.1w
Multiple Spanning Tree Protocol (MSTP) 802.1s
Per-VLAN Spanning Tree Plus (PVST+) Third Party
Congure Spanning Tree
Conguring spanning tree is a two-step process.
• Conguring Interfaces for Layer 2 Mode
• Enabling Spanning Tree Protocol Globally
Related Conguration Tasks
• Adding an Interface to the Spanning Tree Group
• Removing an Interface from the Spanning Tree Group
• Modifying Global Parameters
• Modifying Interface STP Parameters
• Enabling PortFast
• Prevent Network Disruptions with BPDU Guard
• STP Root Guard
• SNMP Traps for Root Elections and Topology Changes
Important Points to Remember
• STP is disabled by default.
• The Dell Networking operating system (OS) supports only one spanning tree instance (0). For multiple instances, enable the
multiple spanning tree protocol (MSTP) or per-VLAN spanning tree plus (PVST+). You may only enable one avor of spanning
tree at any one time.
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Spanning Tree Protocol (STP)