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14-7

Software Configuration Guide—Release 12.2(25)EW

OL-6696-01

Chapter 14 Understanding and Configuring STP

Configuring STP

The following sections describe how to configure spanning tree on VLANs:

• Enabling STP, page 14-7

• Enabling the Extended System ID, page 14-8

• Configuring the Root Bridge, page 14-9

• Configuring a Secondary Root Switch, page 14-12

• Configuring STP Port Priority, page 14-13

• Configuring STP Port Cost, page 14-15

• Configuring the Bridge Priority of a VLAN, page 14-16

• Configuring the Hello Time, page 14-17

• Configuring the Maximum Aging Time for a VLAN, page 14-18

• Configuring the Forward-Delay Time for a VLAN, page 14-18

• Disabling Spanning Tree Protocol, page 14-19

• Enabling Per-VLAN Rapid Spanning Tree, page 14-20

Note The spanning tree commands described in this chapter can be configured on any interface except those

configured with the no switchport command.

Enabling STP

Note By default, spanning tree is enabled on all the VLANs.

You can enable a spanning tree on a per-VLAN basis. The switch maintains a separate instance of

spanning tree for each VLAN (except on VLANs on which you have disabled a spanning tree).

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

Table 14-4 Spanning Tree Default Configuration Values (continued)

Feature Default Value

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