Administrator Guide

Spanning Tree Protocol (STP)

Dell Networking OS supports spanning tree protocol (STP).

Topics:

• Protocol Overview

• Configure Spanning Tree

• Configuring 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 Port Fast

• Global BPDU Filtering

• Selecting STP Root

• STP Root Guard

• SNMP Traps for Root Elections and Topology Changes

• Displaying STP Guard Configuration

Protocol Overview

STP is a Layer 2 protocol — specified 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 65. Dell Networking OS Supported Spanning Tree Protocols

Dell Networking Term IEEE Specification

Spanning Tree Protocol (STP) 802.1d

Rapid Spanning Tree Protocol (RSTP) 802.1w

Multiple Spanning Tree Protocol (MSTP) 802.1s

Spanning Tree Protocol (STP) 869