Quick Reference Guide

152 | Spanning Tree
www.dell.com | support.dell.com
Enabling STP
Use the following commands to run Spanning Tree convergence on participating switches.
Example of configuring STP
Figure 10-110 shows three S-Series switches, S50-1, S50-2, and S50-3. A physical connection exists
between each pair of switches. Enabling the Spanning Tree Protocol (STP) on this topology will enable
one least-cost route between each of the switches, so that redundant packets are not sent in both directions
around the loop.
Figure 10-110. Spanning Tree Topology Example
1. Use the show spanning-tree interface command and show spanning-tree summary command to
determine if STP is initially disabled on the interface and globally (See Figure 10-116 on page 158 and
Example Output from show spanning-tree vlan Command on page 162). Use
show spanning-tree brief
(see Figure 10-118 on page 159) to determine the current bridge characteristics.
2. In Global Config mode on each participating switch, use the
spanning-tree command to enable
Spanning Tree.
spanning tree
Global Config Enable the Spanning Tree Protocol on participating
switches.
spanning-tree port mode enable
Interface Config Enable STP on selected ports.
spanning-tree port mode enable all
Global Config Alternatively to enabling STP on selected ports,
activate STP on all ports.
spanning-tree port mode enable all
Interface Port
Channel Config
Enable STP on participating LAGs.
S50-1
S50-2
S50-3
1/0/1
1/0/2
1/0/1
1/0/2
1/0/2 1/0/1