Activate VLANs

jskfan
jskfan used Ask the Experts™
on

Activate VLANs
I have seen some vlans that show "down" when running show vlans command.
when creating VLANs on a switch do we need to activate the vlan after it gets created. I thought it 's always up as longs as the ports that belong to that vlan are up.

any idea?

thanks
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Instructor
Top Expert 2015
Commented:
Please post the output where you see this. Are you referring to the VLAN interface or the VLAN itself?
Generally speaking a VLAN will be up and its interface reachable as long as there is at least one active port in the VLAN.

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Commented:
donjohnston:
VLAN itself
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Don JohnstonInstructor
Top Expert 2015

Commented:
Please post the output where you see this.

Commented:
What device are you setting the vlans up for? Cisco etc.?

Author

Commented:
this is a cisco switch.
I am not at work now, but I remember we put a different cat5 in place of the existing one in a switch port then connected it to the computer, pingged the DG and no reply. That day we checked the port and it was up, then we checked the vlan and it was down.
usually when you assogn an interface to a vlan, all you need is to activate the port with "No Shut" command, you don't need to do any thing on the vlan to activate it.
Is this a SVI?   In other words,

If you do:

Interface Vlan XXXX
  ...
...

You DO have to do a NO SHUTDOWN to bring the INTERFACE VLAN up.

Author

Commented:
it's not SVI.
it's just a regular VLAN where you add ports to.

Author

Commented:
By thw way the switch is 6500 series, if I remember if 6509.
I am guessing such switches have by default the ports as layer 3 inrefaces.
does it have anything to do with this?

Author

Commented:
So a regular VLAN that has ports associted with it Can't be shut down(Deactivated). Correct?
If you configured a VLAN associated with an interface like this-

Switch(config-if)#switchport access vlan 2

Then you need to enable the interface like this-

Switch(config-if)#no shutdown

Can you show the output of the command so we can get a better idea of what you are seeing when you have this problem?

Author

Commented:
thanks all

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