Useful “show” Commands

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Show Trunking Information

  • show run
  • show interface trunk
  • show interfaces switchport
  • show vlan
    • if the port is active but not listed then it must be a trunk
  • show interfaces interface n/n switchport
  • show interface interface n/n status

Show Port-channel and Etherchannel Information

  • show etherchannel summary
  • show etherchannel port-channel
  • show interfaces port-channel interface n/n
  • show interfaces port-channel interface n/n etherchannel
  • show interface etherchannel

Show VLANs

  • show vlan

Configuring Dynamic Link Aggregation

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Cisco IOS

CiscoSwitch(config)# interface range GigabitEthernet 1/0/1 – 4
CiscoSwitch(config-if)# channel-protocol lacp
CiscoSwitch(config-if)# channel-group 1 mode active

To verify use either show interfaces port-channel 1 etherchannel or show etherchannel summary command.

 

Dell PowerConnect 6200 Series

PC6248(config)# interface range ethernet 1/g17-1/g20
PC6248(config-if)# channel-group 1 mode auto

To verify use the show interfaces port-channel 1 command.

N.B. On Dell 6200 series devices, adding physical ports to a LAG removes them from any VLAN membership. Once they are removed from the LAG they return to their original VLANs. Also, any commands assigned specifically to the physical ports are ignored until they are taken out of the channel-group.

Source: Dell