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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 18 Configuring STP and MST
Default STP Configuration
For enabling information, see “Enabling Per-VLAN Rapid Spanning Tree” on page 20.
Default STP Configuration
Table 18-4 shows the default spanning tree configuration.
Configuring STP
The following sections describe how to configure spanning tree on VLANs:
• Enabling STP, page 18-8
• Enabling the Extended System ID, page 18-9
• Configuring the Root Bridge, page 18-10
• Configuring a Secondary Root Switch, page 18-12
• Configuring STP Port Priority, page 18-13
• Configuring STP Port Cost, page 18-15
• Configuring the Bridge Priority of a VLAN, page 18-17
• Configuring the Hello Time, page 18-17
• Configuring the Maximum Aging Time for a VLAN, page 18-18
• Configuring the Forward-Delay Time for a VLAN, page 18-19
Table 18-4 Spanning Tree Default Configuration Values
Feature Default Value
Enable state Spanning tree enabled for all VLANs
Bridge priority value 32,768
Spanning tree port priority value (configurable on a
per-interface basis—used on interfaces configured as
Layer 2 access ports)
128
Spanning tree port cost (configurable on a per-interface
basis—used on interfaces configured as Layer 2 access
ports)
• 10-Gigabit Ethernet: 2
• Gigabit Ethernet: 4
• Fast Ethernet: 19
Spanning tree VLAN port priority value (configurable on
a per-VLAN basis—used on interfaces configured as
Layer 2 trunk ports)
128
Spanning tree VLAN port cost (configurable on a
per-VLAN basis—used on interfaces configured as
Layer 2 trunk ports)
• 10-Gigabit Ethernet: 2
• Gigabit Ethernet: 4
• Fast Ethernet: 19
Hello time 2 sec
Forward delay time 15 sec
Maximum aging time 20 sec
