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

Damian Higgins linnewbye at gmail.com
Tue Apr 9 15:32:53 EDT 2013


Hi Mike,

How about this scenario. Let's say you want a VLAN tagged on all the ports,
but also want different untagged VLANs on those ports (e.g. port 10 tagged
vlan 306 and untagged vlan 6, port 11 tagged vlan 306 and untagged vlan 7).
So native VLAN is out of question here since all ports would be untagged in
the same VLAN ID.


Can you please test the following setup and tell me if it works? :

interface GigabitEthernet0/10
   description testing cisco vlans
   switchport trunk encapsulation dot1q
   switchport trunk allowed vlan 306
   switchport mode trunk
   switchport access vlan 6


interface GigabitEthernet0/11
   description testing cisco vlans
   switchport trunk encapsulation dot1q
   switchport trunk allowed vlan 306
   switchport mode trunk
   switchport access vlan 7


I don't have any cisco switches at the moment that I could do this test on,
but I can tell you for sure that this setup is possibile on other switches
(HP procurve for example, and they're way cheaper :)

Regards,



On Tue, Apr 9, 2013 at 8:21 PM, Mike
<mike-cisconsplist at tiedyenetworks.com>wrote:

> 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.
>
> Mike-
>
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