Cisco Catalyst 2960 Command Reference Manual page 383

Chapter 2 Catalyst 3750 Switch Cisco IOS Commands
Vlans Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
This is an example of output from the show interfaces switchport backup command. In this 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, 100 to 120, and Gi2/0/6 will
forward traffic for VLANs 1 to 50.
Switch#show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface
------------------------------------------------------------------------
GigabitEthernet2/0/6
Vlans on Interface Gi 2/0/6: 1-50
Vlans on Interface Gi 2/0/8: 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
------------------------------------------------------------------------
GigabitEthernet2/0/6
Vlans on Interface Gi 2/0/6:
Vlans on Interface Gi 2/0/8: 1-50, 60, 100-120
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, then 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
------------------------------------------------------------------------
GigabitEthernet2/0/6
Vlans on Interface Gi 2/0/6: 1-50
Vlans on Interface Gi 2/0/8: 60, 100-120
This is an example of output from the show interfaces interface-id pruning command:
Switch# show interfaces gigibitethernet0/2 pruning
Port
This is an example of output from the show interfaces interface-id trunk command. It displays trunking
information for the port.
Switch# show interfaces gigabitethernet0/1 trunk
Port
Gi0/1
Port
Gi0/1
OL-8604-03
Backup Interface
GigabitEthernet2/0/8
Backup Interface
GigabitEthernet2/0/8
Backup Interface
GigabitEthernet2/0/8
Vlans pruned for lack of request by neighbor
Mode Encapsulation
auto negotiate
Vlans allowed on trunk
1-4094
State
Active Up/Backup Up
State
Active Down/Backup Up
State
Active Up/Backup Up
Status Native vlan
trunking 1
Catalyst 2960 Switch Command Reference
show interfaces
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