Load Sharing Using Stp Path Cost - Cisco WS-C3750-48PS-S Software Configuration Manual

Configuring VLAN Trunks
Command
Step 15 show vlan
Step 16 configure terminal
Step 17
interface gigabitethernet1/ 0/1
Step 18
spanning-tree vlan 8-10 port-priority 16
Step 19 exit
Step 20 interface gigabitethernet1/0/2
Step 21 spanning-tree vlan 3-6 port-priority 16
Step 22
end
Step 23 show running-config
Step 24 copy running-config startup-config

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
assigned:
•
•
•
•
Figure 13-4 Load-Sharing Trunks with Traffic Distributed by Path Cost
VLANs 2
VLANs 8
Catalyst 3750 Switch Software Configuration Guide
13-26
13-4, Trunk ports 1 and 2 are configured as 100BASE-T ports. These VLAN path costs are
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.
Trunk port 1
– 4 (path cost 30)
– 10 (path cost 19)
Switch B
Purpose
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.
Enter global configuration mode on Switch A.
Enter interface configuration mode, and define the interface to set the
STP port priority.
Assign the port priority of 16 for VLANs 8 through 10.
Return to global configuration mode.
Enter interface configuration mode, and define the interface to set the
STP port priority.
Assign the port priority of 16 for VLANs 3 through 6.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Switch A
Trunk port 2
VLANs 8 – 10 (path cost 30)
VLANs 2 – 4 (path cost 19)
Chapter 13 Configuring VLANs
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