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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter13 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, blocking different ports for different VLANs.
The VLANs keep the traffic separate and maintain redundancy in the event of a lost link.
Step5 show vtp status Verify the VTP configuration on both Switch A and Switch B.
In the display, check the VTP Operating Mode and the VTP Domain
Name fields.
Step6 show vlan Verify that the VLANs exist in the database on Switch A.
Step7 configure terminal Enter global configuration mode.
Step8 interface interface-id_1 Define the interface to be configured as a trunk, and enter interface
configuration mode.
Step9 switchport trunk encapsulation {isl |
dot1q | negotiate}
Configure the port to support ISL or IEEE 802.1Q encapsulation or to
negotiate with the neighboring interface. You must configure each end
of the link with the same encapsulation type.
Step10 switchport mode trunk Configure the port as a trunk port.
Step11 end Return to privileged EXEC mode.
Step12 show interfaces interface-id_1 switchport Verify the VLAN configuration.
Step13 Repeat Steps 7 through 11 on Switch A for a second port in the switch
stack.
Step14 Repeat Steps 7 through 11 on Switch B to configure the trunk ports
that connect to the trunk ports configured on Switch A.
Step15 show vlan When the trunk links come up, VTP passes the VTP and VLAN
information to Switch B. Verify that Switch B has learned the VLAN
configuration.
Step16 configure terminal Enter global configuration mode on Switch A.
Step17 interface interface-id_1 Define the interface to set the STP port priority, and enter interface
configuration mode.
Step18 spanning-tree vlan 8-10 port-priority 16 Assign the port priority of 16 for VLANs 8 through 10.
Step19 exit Return to global configuration mode.
Step20 interface interface-id_2 Define the interface to set the STP port priority, and enter interface
configuration mode.
Step21 spanning-tree vlan 3-6 port-priority 16 Assign the port priority of 16 for VLANs 3 through 6.
Step22 end Return to privileged EXEC mode.
Step23 show running-config Verify your entries.
Step24 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose