Specifications

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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
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Chapter 15 Configuring VLANs
Configuring VLAN Trunks
Load Sharing Using STP Path Cost
You can configure parallel trunks to share VLAN traffic by setting different path costs on a trunk and
associating the path costs with different sets of VLANs. The VLANs keep the traffic separate. Because
no loops exist, STP does not disable the ports, and redundancy is maintained in the event of a lost link.
In Figure 15-4, Trunk ports 1 and 2 are 100BASE-T ports. The path costs for the VLANs are assigned
as follows:
• VLANs 2 through 4 are assigned a path cost of 30 on Trunk port 1.
• VLANs 8 through 10 retain the default 100BASE-T path cost on Trunk port 1 of 19.
• VLANs 8 through 10 are assigned a path cost of 30 on Trunk port 2.
• VLANs 2 through 4 retain the default 100BASE-T path cost on Trunk port 2 of 19.
Step 9
switchport mode trunk Configure the port as a trunk port.
Step 10
end Return to privilege EXEC mode.
Step 11
show interfaces fastethernet0/1
switchport
Verify the VLAN configuration.
Step 12
Repeat Steps 7 through 11 on Switch 1 for Fast Ethernet port 0/2.
Step 13
Repeat Steps 7 through 11 on Switch 2 to configure the trunk ports on
Fast Ethernet ports 0/1 and 0/2.
Step 14
show vlan When the trunk links come up, VTP passes the VTP and VLAN
information to Switch 2. Verify that Switch 2 has learned the VLAN
configuration.
Step 15
configure terminal Enter global configuration mode on Switch 1.
Step 16
interface fastethernet0/1 Enter interface configuration mode, and define the interface to set the
STP port priority.
Step 17
spanning-tree vlan 8 port-priority 10 Assign the port priority of 10 for VLAN 8.
Step 18
spanning-tree vlan 9 port-priority 10 Assign the port priority of 10 for VLAN 9.
Step 19
spanning-tree vlan 10 port-priority 10 Assign the port priority of 10 for VLAN 10.
Step 20
exit Return to global configuration mode.
Step 21
interface fastethernet0/2 Enter interface configuration mode, and define the interface to set the
STP port priority.
Step 22
spanning-tree vlan 3 port-priority 10 Assign the port priority of 10 for VLAN 3.
Step 23
spanning-tree vlan 4 port-priority 10 Assign the port priority of 10 for VLAN 4.
Step 24
spanning-tree vlan 5 port-priority 10 Assign the port priority of 10 for VLAN 5.
Step 25
spanning-tree vlan 6 port-priority 10 Assign the port priority of 10 for VLAN 6.
Step 26
end Return to privileged EXEC mode.
Step 27
show running-config Verify your entries.
Step 28
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose