Cisco Catalyst 3750-X Command Reference Manual page 686

show interfaces
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 out put from the show interfaces switchport backup command when a Flex Link
interface goes down (LINK_DOWN), and 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 Preferred on Active Interface: 1-50
Vlans Preferred on Backup Interface: 60, 100-120
This is an example of output from the show interfaces interface-id trunk command. It displays trunking
information for the port.
Switch# show interfaces gigabitethernet1/0/1 trunk
Port
Gi1/0/1
Port
Gi1/0/1
Port
Gi1/0/1
Port
Gi1/0/1
Catalyst 3750-X and 3560-X Switch Command Reference
2-654
Backup Interface
GigabitEthernet2/0/8
Backup Interface
GigabitEthernet2/0/8
Backup Interface
GigabitEthernet2/0/8
Mode Encapsulation
auto negotiate
Vlans allowed on trunk
1-4094
Vlans allowed and active in management domain
1-4
Vlans in spanning tree forwarding state and not pruned
1-4
Chapter 2 Catalyst 3750-X and 3560-X Switch Cisco IOS Commands
State
Active Down/Backup Up
State
Active Up/Backup Up
State
Active Down/Backup Up
Status Native vlan
trunking 1
OL-29704-01