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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter21 Configuring Flex Link s and the MAC Address-Table Move Update Feature
Configuring Flex Links and MAC Address-Table Move Update
Beginning in interface configuration mode, follow these steps to configure a preemption scheme for a
pair of Flex Links:
This example shows how to configure the preemption mode as forced for a backup interface pair and to
verify the configuration:
Switch# configure terminal
Switch(conf)# interface gigabitethernet1/0/1
Switch(conf-if)#switchport backup interface gigabitethernet1/0/2 preemption mode forced
Switch(conf-if)#switchport backup interface gigabitethernet1/0/2 preemption delay 50
Switch(conf-if)# end
Switch# show interface switchport backup detail
Active Interface Backup Interface State
------------------------------------------------------------------------
GigabitEthernet1/0/21 GigabitEthernet1/0/2 Active Up/Backup Standby
Interface Pair : Gi1/0/1, Gi1/0/2
Preemption Mode : forced
Preemption Delay : 50 seconds
Bandwidth : 100000 Kbit (Gi1/0/1), 100000 Kbit (Gi1/0/2)
Mac Address Move Update Vlan : auto
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 Configure a physical Layer 2 interface (or port channel)
as part of a Flex Links pair with the interface. When one
link is forwarding traffic, the other interface is in standby
mode.
Step4 switchport backup interface interface-id preemption
mode [forced | bandwidth | off]
Configure a preemption mechanism and delay for a Flex
Link interface pair. You can configure the preemption as:
•Forced—the active interface always preempts the
backup.
•Bandwidth—the interface with the higher bandwidth
always acts as the active interface.
•Off—no preemption happens from active to backup.
Step5 switchport backup interface interface-id preemption
delay delay-time
Configure the time delay until a port preempts another
port.
Note Setting a delay time only works with forced and
bandwidth modes.
Step6 end Return to privileged EXEC mode.
Step7 show interface [interface-id] switchport backup Verify the configuration.
Step8 copy running-config startup config (Optional) Save your entries in the switch startup
configuration file.