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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
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Chapter12 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 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 12-5, Trunk ports 1 and 2 are configured as 100BASE-T ports. These 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 port 2 of 19 .
Figure12-5 Load-Sharing Trunks with Traffic Distributed by Path Cost
Beginning in privileged EXEC mode, follow these steps to configure the network shown in Figure12-5:
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Switch A
Switch B
Trunk port 1
VLANs 24 (path cost 30)
V
LANs 810 (path cost 19)
Trunk port 2
VLANs 810 (path cost 30)
VLANs 24 (path cost 19)
Command Purpose
Step1 configure terminal Enter global configuration mode on Switch A.
Step2 interface gigabitethernet1/0/1 Define the interface to be configured as a trunk, and enter interface
configuration mode.
Step3 switchport trunk encapsulation
{isl | dot1q | negotiate}Configure the port to support ISL or IEEE 802.1Q enca psu lation. You
must configure each end of the link with the same encapsulation type.
Step4 switchport mode trunk Configure the port as a trunk port. The trunk defaults to ISL trunking.
Step5 exit Return to global configuration mode.
Step6 Repeat Steps 2 through 5 on a second interface in Switch A or in the
Switch A stack.
Step7 end Return to privileged EXEC mode.
Step8 show running-config Verify your entries. In the display, make sure that the interfaces are
configured as trunk ports.
Step9 show vlan When the trunk links come up, Switch A receives the VTP information
from the other switches. Verify that Switch A has learned the VLAN
configuration.
Step10 configure terminal Enter global configuration mode.