Configuring Stp; Enabling Stp - Cisco 7604 Configuration Manual

Configuring STP

Configuring STP
These sections describe how to configure STP on VLANs:
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The STP commands described in this chapter can be configured on any LAN port, but they are in effect
Note
only on LAN ports configured with the switchport keyword.
Caution We do not recommend disabling spanning tree, even in a topology that is free of physical loops. Spanning
tree serves as a safeguard against misconfigurations and cabling errors. Do not disable spanning tree in
a VLAN without ensuring that there are no physical loops present in the VLAN.

Enabling STP

STP is enabled by default on VLAN 1 and on all newly created VLANs.
Note
You can enable STP on a per-VLAN basis. The Cisco 7600 series router maintains a separate instance
of STP for each VLAN (except on VLANs on which you disable STP).
To enable STP on a per-VLAN basis, perform this task:
Command
Step 1
Router(config)# spanning-tree vlan vlan_ID
Router(config)# default spanning-tree vlan
vlan_ID
Router(config)# no spanning-tree vlan vlan_ID
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
20-22
Enabling STP, page 20-22
Enabling the Extended System ID, page 20-24
Configuring the Root Bridge, page 20-24
Configuring a Secondary Root Bridge, page 20-26
Configuring STP Port Priority, page 20-27
Configuring STP Port Cost, page 20-28
Configuring the Bridge Priority of a VLAN, page 20-30
Configuring the Hello Time, page 20-31
Configuring the Forward-Delay Time for a VLAN, page 20-32
Configuring the Maximum Aging Time for a VLAN, page 20-32
Enabling Rapid-PVST, page 20-33
Chapter 20 Configuring STP and Prestandard IEEE 802.1s MST
Purpose
Enables STP on a per-VLAN basis. The vlan_ID value
can be 1 through 4094, except reserved VLANs (see
Table 20-5 on page 20-21).
Reverts all STP parameters to default values for the
specified VLAN.
Disables STP on the specified VLAN; see the following
Cautions for information regarding this command.
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