Installation guide

Cisco HWIC-4ESW and HWIC-D-9ESW EtherSwitch Interface Cards
How to Configure EtherSwitch HWICs
29
Cisco IOS Release 12.3(8)T4
OL-6454-01
DETAILED STEPS
Calculating Port Cost
Port cost value calculations are based on the bandwidth of the port. There are two classes of values. Short
(16-bit) values are specified by the IEEE 802.1D specification, and range in value from 1 to 65535. Long
(32-bit) values are specified by the IEEE 802.1t specification, and range in value from1 to 200,000,000.
Assigning Short Port Cost Values
You can manually assign port costs in the range of 1 to 65535. Default cost values are as follows.
Assigning Long Port Cost Values
You can manually assign port costs in the range of 1 to 200,000,000. Recommended cost values are as
follows.
Verifying Spanning Tree Port Cost
Use the show spanning-tree vlan to verify the spanning-tree port cost configuration.
Router# show spanning-tree vlan 200
Port 264 (FastEthernet0/1/8) of VLAN200 is forwarding
Port path cost 17, Port priority 64, Port Identifier 129.8.
Designated root has priority 32768, address 0010.0d40.34c7
Designated bridge has priority 32768, address 0010.0d40.34c7
Designated port id is 128.1, designated path cost 0
Timers: message age 2, forward delay 0, hold 0
Command Purpose
Step 1
Router(config)# interface {{ethernet |
fastethernet} interface-id
Selects an interface to configure.
Step 2
Router(config-if)# [no] spanning-tree cost
port _ cost
Configures the port cost for an interface. The value of
port_cost can be from 1 to 200,000,000 (1 to 65,535 in
Cisco IOS Releases 12.1(2)E and earlier).
Use the no form of this command to restore the defaults.
Step 3
Router(config-if)# [no] spanning-tree vlan
vlan _ ID cost port _ cost
Configures the VLAN port cost for an interface. The value
port_cost can be from 1 to 65,535.
Use the no form of this command to restore the defaults.
Step 4
Router(config-if)# end
Exits configuration mode.
Port Speed Default Cost Value
10 Mbps 100
100 Mbps 19
Port Speed Recommended Value Recommended Range
10 Mbps 2,000,000 200,000 to 20,000,000
100 Mbps 200,000 20,000 to 2,000,000