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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter21 Configuring Flex Links and the MAC Address-Table Move Update Feature
Configuring Flex Links and the MAC Address-Table Move Update
When a Flex Link interface comes up, VLANs preferred on this interface are blocked on the peer
interface and moved to the forwarding state on the interface that has just come up. In this example, if
interface Gi2/0/6 comes up, VLANs preferred on this interface are blocked on the peer interface Gi2/0/8
and forwarded on Gi2/0/6.
Switch#show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface Backup Interface State
------------------------------------------------------------------------
GigabitEthernet2/0/6 GigabitEthernet2/0/8 Active Up/Backup Up
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
Switch#show interfaces switchport backup detail
Switch Backup Interface Pairs:
Active Interface Backup Interface State
------------------------------------------------------------------------
GigabitEthernet1/0/3 GigabitEthernet1/0/4 Active Down/Backup Up
Vlans Preferred on Active Interface: 1-2,5-4094
Vlans Preferred on Backup Interface: 3-4
Preemption Mode : off
Bandwidth : 10000 Kbit (Gi1/0/3), 100000 Kbit (Gi1/0/4)
Mac Address Move Update Vlan : auto
Configuring the MAC Address-Table Move Update Feature
This section contains this information:
Configuring a switch to send MAC address-table move updates
Configuring a switch to get MAC address-table move updates
Beginning in privileged EXEC mode, follow these steps to configure an access switch to send MAC
address-table move updates:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 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.
Step3 switchport backup interface interface-id
or
switchport backup interface interface-id mmu
primary vlan vlan-id
Configure a physical Layer 2 interface (or port channel),
as part of a Flex Link pair with the interface. The MAC
address-table move update VLAN is the lowest VLAN ID
on the interface.
Configure a physical Layer 2 interface (or port channel)
and specify the VLAN ID on the interface, which is used
for sending the MAC address-table move update.
When one link is forwarding traffic, the other interface is
in standby mode.