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Cisco ME 3400 EthernetAccess Switch SoftwareConfiguration Guide
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Chapter11 Configuring VLANs Configuring VLAN Trunks
Follow the same steps on Switch B to configure the trunk port for Trunk 1 with a spanning-tree port
priority of 16 for VLANs 8 through 10, and the configure trunk port for Trunk 2 with a spanning-tree
port priority of 16 for VLANs 3 through 6.
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 po rts for d ifferent V LA Ns.
The VLANs keep the traffic separate and maintain redundancy in the event of a lo st l ink.
In Figure 11-4, Trunk ports 1 and 2 are configured as 100Base-T ports. Thes e VLAN p ath co sts a re
assigned:
•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 1 9.
•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 por t 2 of 19 .
Figure11-4 Load-Sharing Trunks with Traffic Distributed by Path Cost
Step17 interface gigabitethernet 0/2 Define the interface to be configured as the Trunk 2 interface, and
enter interface configuration mode.
Step18 port-type nni Configure the interface as an NNI.
Step19 switchport mode trunk Configure the port as a trunk port.
Step20 spanning-tree vlan 3-6 port-priority 16 Assign the port priority of 16 for VLANs 3 through 6 on Trunk 2.
Step21 end Return to privileged EXEC mode.
Step22 show interfaces gigabitethernet 0/2
switchport Verify the port configuration.
Step23 show running-config Verify your entries.
Step24 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
90573
Switch A
Switch B
Trunk port 1
VLANs 2 – 4 (path cost 30)
VLANs 8 – 10 (path cost 19)
Trunk port 2
VLANs 8 – 10 (path cost 30)
VLANs 2 – 4 (path cost 19)