Cisco Systems RJ-45-to-AUX manual Configuring STP on an IOS Command−Based Switch, 214

Bridge Max Age 20 Sec			Hello Time 2 sec Forward Delay 15 sec
Port vlan Port−State			Cost	Priority	Fast−start Group−Method
———— ———— ——————————			————	————————	—————————— ————————————
5/1	2	forwarding	19	32	disabled
5/2	2	forwarding	19	32	disabled
5/3	2	blocking	19	32	disabled
5/4	2	blocking	19	32	disabled

The listing at the bottom of the output shows the ports in use in the spanning tree. It states the port, port−state, and priority, as well as whether Fast−Start (PortFast) is enabled.

Table 10.6: The show spantree command output fields.

Field	Description
Spanning tree enabled	Shows that STP is in use
Spanning tree type	Typically the IEEE standard
Designated Root	The 6−byte MAC address for the designated root bridge
Designated Root Priority	The 2−byte priority setting for the root bridge
Designated Root Cost	Total cost to get to the root bridge from this switch (0 indicates the root
	switch)
Designated Root Port	The port used to get to the root bridge
Root timers	Timer values of the root bridge or switch; these include the MaxAge,
	Hello Time, and Forward Delay timer values
Bridge ID MAC ADDR	The 6−byte address that the switch uses for its bridge ID
Bridge ID Priority	The 2−byte priority of this bridge
Bridge Max Age	The maximum values from the root bridge

Configuring STP on an IOS Command−Based Switch

Unlike the Set/Clear command−based switch, enabling the Spanning Tree Protocol on a Cisco IOS command−based switch is performed in Global Configuration mode. To enable STP, enter the following command:

spantree <VLAN list>

In the following example, 5 is the VLAN number and is considered a VLAN−list field; you can include up to

10 VLANs in the list:

spantree 5

Disabling STP on an IOS Command−Based Switch

To disable STP on a VLAN, in Global Configuration mode use this command:

no spantree <VLAN list>

In this example, 5 is the VLAN number and is considered a VLAN−list field:

no spantree 5

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