Administrator Guide
Spanning Tree Protocol (STP)
Spanning tree protocol (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.
Topics:
• Protocol Overview
• Congure Spanning Tree
• Conguring Interfaces for Layer 2 Mode
• Enabling Spanning Tree Protocol Globally
• 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
• Global BPDU Filtering
• Interface BPDU Filtering
• Selecting STP Root
• STP Root Guard
• Enabling SNMP Traps for Root Elections and Topology Changes
• Conguring Spanning Trees as Hitless
• STP Loop Guard
• Displaying STP Guard Conguration
Protocol Overview
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 STP, can cause unnecessarily
high switch CPU utilization and memory consumption.
Dell Networking OS supports three other variations of spanning tree, as shown in the following table.
Table 95. 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
57
Spanning Tree Protocol (STP) 919