Cisco Catalyst 1900 Series, Brochure

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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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