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Catalyst 3750 Switch Software Configuration Guide
OL-8550-09
Chapter 13 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.
Step 5
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.
Step 6
show vlan Verify that the VLANs exist in the database on Switch A.
Step 7
configure terminal Enter global configuration mode.
Step 8
interface interface-id_1 Define the interface to be configured as a trunk, and enter interface
configuration mode.
Step 9
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.
Step 10
switchport mode trunk Configure the port as a trunk port.
Step 11
end Return to privileged EXEC mode.
Step 12
show interfaces interface-id_1 switchport Verify the VLAN configuration.
Step 13
Repeat Steps 7 through 11 on Switch A for a second port in the switch
stack.
Step 14
Repeat Steps 7 through 11 on Switch B to configure the trunk ports
that connect to the trunk ports configured on Switch A.
Step 15
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.
Step 16
configure terminal Enter global configuration mode on Switch A.
Step 17
interface interface-id_1 Define the interface to set the STP port priority, and enter interface
configuration mode.
Step 18
spanning-tree vlan 8-10 port-priority 16 Assign the port priority of 16 for VLANs 8 through 10.
Step 19
exit Return to global configuration mode.
Step 20
interface interface-id_2 Define the interface to set the STP port priority, and enter interface
configuration mode.
Step 21
spanning-tree vlan 3-6 port-priority 16 Assign the port priority of 16 for VLANs 3 through 6.
Step 22
end Return to privileged EXEC mode.
Step 23
show running-config Verify your entries.
Step 24
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose