Load Sharing Using Stp Path Cost - Cisco 3845 - Security Bundle Router Software Manual

Chapter 10 Configuring VLANs
Figure 10-2
VLANs 8 – 10 (priority 16)
VLANs 3 – 6 (priority 128)
Beginning in privileged EXEC mode on Switch A, follow these steps to configure the network shown in
Figure
Command
Step 7 show vlan
Step 8
configure terminal
Step 9
interface gigabitethernet 0/1
Step 10
switchport mode trunk
Step 11
spanning-tree vlan 8-10 port-priority 16
Step 12
end
Step 13
show interfaces gigabitethernet 0/1
switchport
Step 14 configure terminal
Step 15 interface gigabitethernet 0/2
Step 16
switchport mode trunk
Step 17
spanning-tree vlan 3-6 port-priority 16
Step 18
end
Step 19
show interfaces gigabitethernet 0/2
switchport
Step 20 show running-config
Step 21 copy running-config startup-config
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 ports for different VLANs.
The VLANs keep the traffic separate and maintain redundancy in the event of a lost link.
OL-23400-01
Load Sharing by Using STP Port Priorities
Trunk 1
Switch B
10-2. Note that you can use any interface numbers; those shown are examples only.
Switch A
Trunk 2
VLANs 3 – 6 (priority 16)
VLANs 8 – 10 (priority 128)
Purpose
Verify that the referenced VLANs exist on Switch A. If not, create the
VLANs by entering the VLAN IDs.
Enter global configuration mode.
Define the interface to be configured as the Trunk 1 interface, and
enter interface configuration mode.
Configure the port as a trunk port.
Assign the port priority of 16 for VLANs 8 through 10 on Trunk 1.
Return to privileged EXEC mode.
Verify the port configuration.
Enter global configuration mode.
Define the interface to be configured as the Trunk 2 interface, and
enter interface configuration mode.
Configure the port as a trunk port.
Assign the port priority of 16 for VLANs 3 through 6 on Trunk 2.
Return to privileged EXEC mode.
Verify the port configuration.
Verify your entries.
(Optional) Save your entries in the configuration file.
Cisco ME 3800X and 3600X Switch Software Configuration Guide
Configuring VLAN Trunks
10-15