Quick Reference Guide

Spanning Tree | 145

Spanning Tree

This chapter discusses the SFTOS implementation of Spanning Tree Protocol (STP), Multiple Spanning

Tree Protocol (MSTP), and Rapid Spanning Tree Protocol (RSTP). The chapter contains the following

major sections:

• SFTOS STP Switching Features

• Spanning Tree Protocol (STP, IEEE 802.1D) on page 146

• Rapid Spanning Tree Protocol (RSTP, IEEE 802.1w) on page 147

• Multiple Spanning-Tree Protocol (MSTP, IEEE 802.1s) on page 148

• Spanning Tree Configuration Tasks on page 150

• Setting the STP Version Parameter on page 151

• Enabling STP on page 152

• MSTP Configuration Example on page 156

• Display Spanning Tree Configuration on page 157

SFTOS STP Switching Features

• Forwarding, Aging, and Learning

• Spanning Tree, IVL and STP per VLAN

• IEEE 802.1D — Spanning Tree Protocol (STP)

• IEEE 802.1w — Rapid Spanning Tree Protocol (RSTP)

• IEEE 802.1s — Multiple Spanning Tree Protocol (MSTP)

Forwarding, Aging, and Learning

• Forwarding: At Layer 2, frames are forwarded according to their MAC address.

• Aging: SFTOS supports a user-configurable address-aging timeout parameter, defined in IEEE 802.1D.

• Learning:

— SFTOS learns and manages MAC addresses, as specified in IEEE 802.1D and IEEE

802.1q.

— SFTOS supports Shared VLAN Learning (SVL), although Independent VLAN Learning

(IVL) is the default.

Note: The default spanning tree mode in SFTOS is IEEE 802.1s (MSTP), which is

backward-compatible with IEEE 802.1D and IEEE 802.1w. Those standalone legacy modes are

also available in SFTOS, as described in Setting the STP Version Parameter on page 151.