[c-nsp] 3560g switch - tagged vlans and untagged frames

Mike mike-cisconsplist at tiedyenetworks.com
Tue Apr 9 13:21:42 EDT 2013

On 04/08/2013 09:48 PM, sthaug at nethelp.no wrote:
>> 	I would like to be able to accept both tagged and untagged frames on my
>> 3560g. For the untagged frames, I'd like to be able to say these are a
>> member of some vlan - say 100 - otherwise I want to be able to allow
>> tagged frames from some list.
>> 	In testing, it doesn't appear that "switchport trunk native vlan xxxx"
>> is doing the job; anything I send untagged is dropped and doesn't show
>> up in the switch mac address tables.  Here is my config:
> Similar configs work for us.
>> interface GigabitEthernet0/45
>>    description testing cisco vlans
>>    switchport trunk encapsulation dot1q
>>    switchport trunk native vlan 6
>>    switchport trunk allowed vlan 306
>>    switchport mode trunk
>> It it helps. I do also have dot1q native vlan tagging enabled.
> I believe you need to drop that - it tells the switch that the native
> VLAN should be tagged.
> Also, add the native VLAN to the list of allowed VLANs (so you'd get
> "switchport trunk allowed vlan 6,306" here).

I removed dot1q tag native and that seems to have worked. Unfortunately, 
it caused other problems requiring me to set the native vlans on some 
ports to something other than default. In the end it's working but I 
just don't see why I can't say 'hey, got an untagged frame? throw it 
into this vlan for me...'. Maybe I need more expensive switches.

Thanks all.


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