Load Sharing Using Stp Path Cost - Cisco Catalyst 2950 Software Configuration Manual

Chapter 16 Configuring VLANs
Command
Step 17 spanning-tree vlan 8-10 port-priority 16
Step 18
spanning-tree vlan 10 port-priority 16
Step 19 exit
Step 20 interface fastethernet 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. The VLANs keep the traffic separate. Because
no loops exist, STP does not disable the ports, and redundancy is maintained in the event of a lost link.
In Figure
as follows:
•
•
•
•
Figure 16-4
VLANs 2
VLANs 8
78-11380-12
16-4, Trunk ports 1 and 2 are 100BASE-T ports. The path costs for the VLANs 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.
Load-Sharing Trunks with Traffic Distributed by Path Cost
Trunk port 1
– 4 (path cost 30)
– 10 (path cost 19)
Switch B
Purpose
Assign the port priority of 16 for VLANs 8 through 10.
Assign the port priority of 16 for VLAN 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)
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
Configuring VLAN Trunks
16-23