Cisco Catalyst 3550 Series - Load Sharing Using STP Path Cost

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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 12 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. 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.
Step 6
show vlan Verify that the VLANs exist in the database on Switch 1.
Step 7
configure terminal Enter global configuration mode.
Step 8
interface fastethernet 0/1 Enter interface configuration mode, and define Fast Ethernet port 0/1
as the interface to be configured as a trunk.
Step 9
switchport trunk encapsulation {isl |
dot1q | negotiate}
Configure the port to support ISL or 802.1Q encapsulation or to
negotiate with the neighboring interface.
You must configure each end of the link with the same encapsulation
type.
Step 10
switchport mode trunk Configure the port as a trunk port.
Step 11
end Return to privilege EXEC mode.
Step 12
show interfaces fastethernet0/1
switchport
Verify the VLAN configuration.
Step 13
Repeat Steps 7 through 11 on Switch 1 for Fast Ethernet port 0/2.
Step 14
Repeat Steps 7 through 11 on Switch 2 to configure the trunk ports on
Fast Ethernet ports 0/1 and 0/2.
Step 15
show vlan When the trunk links come up, VTP passes the VTP and VLAN
information to Switch 2. Verify that Switch 2 has learned the VLAN
configuration.
Step 16
configure terminal Enter global configuration mode on Switch 1.
Step 17
interface fastethernet0/1 Enter interface configuration mode, and define the interface to set the
STP port priority.
Step 18
spanning-tree vlan 8 port-priority 10 Assign the port priority of 10 for VLAN 8.
Step 19
spanning-tree vlan 9 port-priority 10 Assign the port priority of 10 for VLAN 9.
Step 20
spanning-tree vlan 10 port-priority 10 Assign the port priority of 10 for VLAN 10.
Step 21
exit Return to global configuration mode.
Step 22
interface fastethernet0/2 Enter interface configuration mode, and define the interface to set the
STP port priority.
Step 23
spanning-tree vlan 3 port-priority 10 Assign the port priority of 10 for VLAN 3.
Step 24
spanning-tree vlan 4 port-priority 10 Assign the port priority of 10 for VLAN 4.
Step 25
spanning-tree vlan 5 port-priority 10 Assign the port priority of 10 for VLAN 5.
Step 26
spanning-tree vlan 6 port-priority 10 Assign the port priority of 10 for VLAN 6.
Step 27
end Return to privileged EXEC mode.
Step 28
show running-config Verify your entries.
Step 29
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose