2.5.2 - Force10 Networks

Chapter 9 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 154
• Rapid Spanning Tree Protocol (RSTP, IEEE 802.1w) on page 155
• Multiple Spanning-Tree Protocol (MSTP, IEEE 802.1s) on page 156
• Spanning Tree Configuration Tasks on page 159
• Setting the STP Version Parameter on page 159
• Enabling STP on page 160
• MSTP Configuration Example on page 164
• Display Spanning Tree Configuration on page 165
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)
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 159.
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.
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