Chapter 19
Configuring Flex Links and the MAC Address-Table Move Update Feature
Configuring VLAN Load Balancing on Flex Links
Beginning in privileged EXEC mode, follow these steps to configure VLAN load balancing on Flex
Links:
Command
Step 1
configure terminal
Step 2
interface interface-id
Step 3
switchport backup interface interface-id prefer vlan
vlan-range
Step 4
end
Step 5
show interfaces [interface-id] switchport backup
Step 6
copy running-config startup config
To disable the VLAN load balancing feature, use the no switchport backup interface interface-id
prefer vlan vlan-range interface configuration command.
In the following example, VLANs 1 to 50, 60, and 100 to 120 are configured on the switch:
Switch(config)#interface gigabitEthernet 1/2
Switch(config-if)#switchport backup interface gigabitEthernet 1/2 prefer vlan 60,100-120
When both interfaces are up, Gi1/1 forwards traffic for VLANs 60 and 100 to 120, and Gi1/2 forwards
traffic for VLANs 1 to 50.
Switch#show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface
------------------------------------------------------------------------
GigabitEthernet1/6
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
When a Flex Link interface goes down (LINK_DOWN), VLANs preferred on this interface are moved
to the peer interface of the Flex Link pair. In this example, if interface Gi1/1 goes down, Gi1/2 carries
all VLANs of the Flex Link pair.
Switch#show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface
------------------------------------------------------------------------
GigabitEthernet1/1 GigabitEthernet1/2 Active Down/Backup Up
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
OL-13018-01
Configuring Flex Links and the MAC Address-Table Move Update
Purpose
Enter global configuration mode.
Specify the interface, and enter interface configuration
mode. The interface can be a physical Layer 2 interface or
a port channel (logical interface). The port-channel range
is 1 to 6.
Configure a physical Layer 2 interface (or port channel)
as part of a Flex Links pair with the interface, and specify
the VLANs carried on the interface. The VLAN ID range
is 1 to 4094.
Return to privileged EXEC mode.
Verify the configuration.
(Optional) Save your entries in the switch startup
configuration file.
Backup Interface
GigabitEthernet1/2 Active Up/Backup Up
Backup Interface
Cisco IE 3000 Switch Software Configuration Guide
State
State
19-11