Cisco WS-C3750-48PS-S User Manual

13-26
Catalyst 3750 Switch Software Configuration Guide
78-16180-02
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.
In Figure 13-4, Trunk ports 1 and 2 are configured as 100BASE-T ports. These VLAN path costs are
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 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.
Figure 13-4 Load-Sharing Trunks with Traffic Distributed by Path Cost
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 gigabitethernet1/ 0/1 Enter interface configuration mode, and define the interface to set the
STP port priority.
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 gigabitethernet1/0/2 Enter interface configuration mode, and define the interface to set the
STP port priority.
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
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)

Cisco WS-C3750-48PS-S Specifications

General

Brand	Cisco
Model	WS-C3750-48PS-S
Category	Switch
Language	English