Trunk,allowed list,native VLAN

[rmv72]

Hi,

while reading CVOICE book by Kevin Wallace i found example of configuring trunk ports with 2 vlans(data and voice) allowed via trunk port. Data vlan presented as native vlan.

And below note "The native VLAN does not have to be explicitly permitted in the allowed VLAN list."

Why?

Best regards,

Mike

[glen.grant · Accepted solution]

  The question back is why would you need to . By definition a native vlan is a vlan  in which the packets "are not tagged " going across the link so technically it's not part of the actual trunk where other vlans are tagged before sending the traffic across the link so it would make no sense to allow it across the trunk because the packets will not be tagged because it is the native vlan. Technically best practice is to create a "dummy" vlan as the native vlan  and trunk everything else .    That being said just to confuse things you can thru a command tell the switch to tag the native vlan  also but by default it does not get tagged.

[smehrnia · Accepted solution]

Hi there,

Bcause the traffic of the native vlan does not get tagged, and with no vlan tag it doesnt belong to any vlan (tech view) but the one we preset as native vlan. in other word; the alowed list is checked against packets vlan ID and packets from native vlan doesnt have any! therefor it doesnt need to be explicitly allowed.

Hope it Helps,

Soroush.

[rmv72]

Thank you!

It is clear now.

Best regards,

Mike