Chapter 21 Configuring Flex Links and the MAC Address-Table Move Update Feature

Configuring Flex Links and MAC Address-Table Move Update

Configuring VLAN Load Balancing on Flex Links

Beginning in privileged EXEC mode, follow these steps to configure VLAN load balancing on Flex Links:

 

Command

Purpose

Step 1

 

 

configure terminal

Enter global configuration mode.

Step 2

 

 

interface interface-id

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 48.

 

 

 

Step 3 switchport backup interface interface-idprefer vlan

Configure a physical Layer 2 interface (or port channel)

 

vlan-id

as part of a Flex Links pair with the interface. When one

 

 

link is forwarding traffic, the other interface is in standby

 

 

mode.

Step 4

 

 

end

Return to privileged EXEC mode.

Step 5

 

 

show interfaces [interface-id]switchport backup

Verify the configuration.

Step 6

 

 

copy running-config startup config

(Optional) Save your entries in the switch startup

 

 

configuration file.

 

 

 

In the following example, VLANs 1 to 50, 60, and 100 to 120 are configured on the switch:

Switch(config)#interface gigabitEthernet 2/0/6

Switch(config-if)#switchport backup interface gigabitEthernet 2/0/8 prefer vlan 60,100-120

When both interfaces are up, Gi2/0/8 forwards traffic for VLANs 60 and 100 to 120 and Gi2/0/6 forwards traffic for VLANs 1 to 50.

Switch#show interfaces switchport backup

Switch Backup Interface Pairs:

Active Interface Backup Interface State

------------------------------------------------------------------------

GigabitEthernet2/0/6

GigabitEthernet2/0/8

Active Up/Backup Standby

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 Gi2/0/6 goes down, Gi2/0/8 carries all VLANs of the Flex Link pair.

Switch#show interfaces switchport backup

Switch Backup Interface Pairs:

Active Interface Backup Interface State

------------------------------------------------------------------------

GigabitEthernet2/0/6

GigabitEthernet2/0/8

Active Down/Backup Up

Vlans

Preferred on

Active

Interface:

1-50

 

Vlans

Preferred on

Backup

Interface:

60, 100-120

 

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

21-8

OL-9775-02

 

 

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Image 514
Cisco Systems 3750E Configuring Vlan Load Balancing on Flex Links, Switchport backup interface interface-id prefer vlan