Changing native vlan on access port

Discussion in 'Cisco' started by Dedan, Aug 12, 2009.

  1. Dedan

    Dedan Guest

    I've have a scenario where a cisco switch is being connected to a
    switch that doesn't support Vlans. That 2nd switch is sending frames
    without vlan tags and I want them to be placed into vlan 801. My
    thoughts are that the config to do this would simply be

    switchport access vlan 801
    switchport mode access

    but I've seen a coworker use the config below

    switchport access vlan 801
    switchport trunk native vlan 801
    switchport mode access

    I know that the middle line changes the native vlan on a trunk port to
    801, but why would you do this on an access port? It was my
    understanding that on an acess port the switch wiill insert a Vlan 801
    tag into any frames it recieves on that port. I guess my question is
    what affect does chaning the native vlan on an access port have? Does
    it place any untagged frames into vlan 801? If that's the case why
    doesn't just making it an access port work. No joy on checking
    command references only for switchport trun native vlan
     
    Dedan, Aug 12, 2009
    #1
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  2. Dedan

    Blaz Zupan Guest

    On 2009-08-12, Dedan <> wrote:
    > I've have a scenario where a cisco switch is being connected to a
    > switch that doesn't support Vlans. That 2nd switch is sending frames
    > without vlan tags and I want them to be placed into vlan 801. My
    > thoughts are that the config to do this would simply be
    >
    > switchport access vlan 801
    > switchport mode access
    >
    > but I've seen a coworker use the config below
    >
    > switchport access vlan 801
    > switchport trunk native vlan 801
    > switchport mode access
    >
    > I know that the middle line changes the native vlan on a trunk port to
    > 801, but why would you do this on an access port? It was my
    > understanding that on an acess port the switch wiill insert a Vlan 801
    > tag into any frames it recieves on that port. I guess my question is
    > what affect does chaning the native vlan on an access port have? Does
    > it place any untagged frames into vlan 801? If that's the case why
    > doesn't just making it an access port work. No joy on checking
    > command references only for switchport trun native vlan


    In the above configuration the "switchport trunk native" command is
    ignored. It will only be used if you switch over to "switchport mode
    trunk".

    Ignoring VTP and CDP, the following two configurations would have the
    same effect:

    switchport mode access
    switchport access vlan 801

    is similar to

    switchport mode trunk
    switchport trunk native vlan 801
    switchport trunk allow vlan 801

    Hope this clears it up and doesn't confuse you even more ;)
     
    Blaz Zupan, Aug 13, 2009
    #2
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  3. Dedan

    Dedan Guest

    Thanks. I'd figured that was the case but was having trouble
    convincing myself.
     
    Dedan, Aug 17, 2009
    #3
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