Reference Guide

Spanning Tree Protocol | 689
Adding an Interface to the Spanning Tree Group
To add a Layer 2 interface to the Spanning Tree topology:
Removing an Interface from the Spanning Tree Group
To remove a Layer 2 interface from the Spanning Tree topology:
Modifying Global Parameters
You can modify Spanning Tree parameters. The root bridge sets the values for forward-delay, hello-time,
and max-age and overwrites the values set on other bridges participating in Spanning Tree.
Table 38-2 displays the default values for Spanning Tree.
Task Command Syntax Command Mode
Enable Spanning Tree on a Layer 2 interface.
spanning-tree 0
INTERFACE
Task Command Syntax Command Mode
Disable Spanning Tree on a Layer 2 interface.
no spanning-tree 0
INTERFACE
In FTOS versions prior to 7.6.1.0, the command no spanning tree disables Spanning Tree on the interface,
however, BPDUs are still forwarded to the RPM, where they are dropped. Beginning in FTOS version 7.6.1.0,
the command
no spanning tree disables Spanning Tree on the interface, and incoming BPDUs are dropped at
the line card instead of at the RPM, which frees processing resources. This behavior is called Layer 2 BPDU
filtering and is available for STP, RSTP, PVST+, and MSTP.
Note: Dell Networking recommends that only experienced network administrators change the Spanning
Tree parameters. Poorly planned modification of the Spanning Tree parameters can negatively impact
network performance.
Table 38-2. STP Default Values
STP Parameter Default Value
Forward Delay 15 seconds
Hello Time 2 seconds
Max Age 20 seconds