Cisco Catalyst 4500 series Administration Manual page 683

Chapter 23 Configuring Flex Links and MAC Address-Table Move Update
When both interfaces are up, Fast Ethernet port 1/0/8 forwards traffic for VLANs 60 and 100 to 120 and
Fast Ethernet port 1/0/6 forwards traffic for VLANs 1 to 50.
Switch# show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface
------------------------------------------------------------------------
FastEthernet1/6
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
When a Flex Links interface shuts down, VLANs preferred on this interface are moved to the peer
interface of the Flex Links pair. In this example, if interface 1/6 shuts down, interface 1/8 carries all
VLANs of the Flex Links pair.
Switch# show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface
------------------------------------------------------------------------
FastEthernet1/6 FastEthernet1/8
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
When a Flex Links interface becomes active, 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 Fast Ethernet port 1/6 becomes active, VLANs preferred on this interface are blocked on the
peer interface Fast Ethernet port 1/8 and forwarded on Fast Ethernet port 1/6.
Switch# show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface
------------------------------------------------------------------------
FastEthernet1/6
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
------------------------------------------------------------------------
FastEthernet1/6
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
Preemption Mode
Bandwidth : 10000 Kbit (Fa1/6), 100000 Kbit (Fa1/8)
Mac Address Move Update Vlan : auto
OL_28731-01
Backup Interface
FastEthernet1/8 Active Up/Backup Standby
Backup Interface
Active Down/Backup VLB all
Backup Interface
FastEthernet1/8 Active VLB cfg/Backup VLB cfg
Backup Interface
FastEthernet1/8
: off
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
State
State
State
State
Active VLB cfg/Backup VLB cfg
Configuring Flex Links
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