Spanning Tree Domains - Extreme Networks ExtremeWare Command Reference Manual

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STP Commands

Spanning Tree Domains

The switch can be partitioned into multiple virtual bridges. Each virtual bridge can run an independent

Spanning Tree instance. Each Spanning Tree instance is called a Spanning Tree Domain (STPD). Each

STPD has its own root bridge and active path. After an STPD is created, one or more VLANs can be

assigned to it.

A port can belong to multiple STPDs. In addition, a VLAN can span multiple STPDs.

The key points to remember when configuring VLANs and STP are:

• Each VLAN forms an independent broadcast domain.

• STP blocks paths to create a loop-free environment.

• When STP blocks a path, no data can be transmitted or received on the blocked port.

• Within any given STPD, all VLANs belonging to it use the same spanning tree.

If you delete a STPD, the VLANs that were members of that STPD are also deleted. You must remove

all VLANs associated with the STP before deleting the STPD.

An STPD has two modes of operation:

• 802.1d mode

Use this mode for backward compatibility with previous STP versions and for compatibility with

third-party switches using IEEE standard 802.1d. When an STPD is configured in this mode, all

rapid configuration mechanisms are disabled.

• 802.1w mode

Use this mode for compatibility with Rapid Spanning Tree (RSTP). When an STPD is configured in

this mode, all rapid configuration mechanisms are enabled. This mode is available for point-to-point

RSTP is enabled or disabled on a per STPD basis only. You do not enable RSTP on a per port basis.

Use this mode for compatibility with Multiple Spanning Tree (MSTP, 802.1s). MSTP is an extension

of RSTP and offers the benefit of better scaling with fast convergence. When an STPD is configured

in this mode, all rapid configuration mechanisms are enabled. Like 802.1w mode, the benefit of

MSTP mode is available on point-to-point links and when the peer is likewise configured in MSTP

You can create only one MSTP region on the switch, and all switches that participate in the region

must have the same regional configurations. You enable or disable an MSTP on a per STPD basis

only. You do not enable MSTP on a per port basis.

By default, the following conditions exist:

• STPD operates in 802.1d mode.

• The default device configuration contains a single STPD called s0.

• The default VLAN is a member of STPD s0.

All STP parameters default to the IEEE 802.1d values, as appropriate.

ExtremeWare 7.7 Command Reference Guide

Extremeware 7.7