Vlan-Bridge Spanning Tree; Configuring Spanning-Tree Features; Default Spanning-Tree Configuration - Cisco WS-C3560-48PS-S Software Configuration Manual

Chapter 15 Configuring STP

VLAN-Bridge Spanning Tree

Cisco VLAN-bridge spanning tree is used with the fallback bridging feature (bridge groups), which
forwards non-IP protocols such as DECnet between two or more VLAN bridge domains or routed ports.
The VLAN-bridge spanning tree allows the bridge groups to form a spanning tree on top of the individual
VLAN spanning trees to prevent loops from forming if there are multiple connections among VLANs.
It also prevents the individual spanning trees from the VLANs being bridged from collapsing into a
single spanning tree.
To support VLAN-bridge spanning tree, some of the spanning-tree timers are increased. To use the
fallback bridging feature, you must have the enhanced multilayer software image installed on your
switch. For more information, see

Configuring Spanning-Tree Features

These sections describe how to configure spanning-tree features:
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Default Spanning-Tree Configuration

Table 15-3
Table 15-3 Default Spanning-Tree Configuration
Feature
Enable state
Spanning-tree mode
Switch priority
Spanning-tree port priority (configurable on a per-interface basis)
78-16156-01
Default Spanning-Tree Configuration, page 15-11
Spanning-Tree Configuration Guidelines, page 15-12
Changing the Spanning-Tree Mode, page 15-13
Disabling Spanning Tree, page 15-14
Configuring the Root Switch, page 15-14
Configuring a Secondary Root Switch, page 15-16
Configuring Port Priority, page 15-17
Configuring Path Cost, page 15-18
Configuring the Switch Priority of a VLAN, page 15-19
Configuring Spanning-Tree Timers, page 15-20
shows the default spanning-tree configuration.
Chapter 34, "Configuring Fallback Bridging."
(required)
(optional)
(optional)
(optional)
(optional)
(optional)
(optional)
Default Setting
Enabled on VLAN 1.
For more information, see the
Spanning-Tree Instances" section on
page
PVST+. (Rapid PVST+ and MSTP are
disabled.)
32768.
128.
Catalyst 3560 Switch Software Configuration Guide
Configuring Spanning-Tree Features
(optional)
15-9.
"Supported
15-11