Quick Reference Guide
PowerConnect B-Series TI24X Configuration Guide 93
53-1002269-02
Chapter
6
Configuring Spanning Tree Protocol (STP) Related Features
STP overview
The Spanning Tree Protocol (STP) eliminates Layer 2 loops in networks, by selectively blocking
some ports and allowing other ports to forward traffic, based on global (bridge) and local (port)
parameters you can configure.
STP related features, such as RSTP and PVST, extend the operation of standard STP, enabling you
to fine-tune standard STP and avoid some of its limitations.
You can enable or disable STP on a global basis (for the entire device), a port-based VLAN basis (for
the individual Layer 2 broadcast domain), or an individual port basis.
Configuration procedures are provided for the standard STP bridge and port parameters as well as
features listed in Table 26.
Configuring standard STP parameters
PowerConnect devices support standard STP as described in the IEEE 802.1D specification.
By default, each port-based VLAN on a PowerConnect device runs a separate spanning tree (a
separate instance of STP). A PowerConnect device has one port-based VLAN (VLAN 1) by default
that contains all the device ports. Thus, by default each PowerConnect device has one spanning
tree. However, if you configure additional port-based VLANs on a PowerConnect device, then each
of those VLANs on which STP is enabled and VLAN 1 all run separate spanning trees.
If you configure a port-based VLAN on the device, the VLAN has the same STP state as the default
STP state on the device. Thus, on Layer 2 Switches, new VLANs have STP enabled by default. On
Layer 3 Switches, new VLANs have STP disabled by default. You can enable or disable STP in each
VLAN separately. In addition, you can enable or disable STP on individual ports.
STP parameters and defaults
Table 21 lists the default STP states for PowerConnect devices.
TABLE 21 Default STP states
Device type Default STP type Default STP state Default STP state of new
VLANs
1
1. When you create a port-based VLAN, the new VLAN STP state is the same as the default STP state on the
device. The new VLAN does not inherit the STP state of the default VLAN.
Layer 2 Switch MSTP
2
Enabled Enabled
Layer 3 Switch MSTP Disabled Disabled