Remove VLAN 1 from trunk on 3500XL platform?

Discussion in 'Cisco' started by Thomas Novin, Sep 29, 2004.

  1. Thomas Novin

    Thomas Novin Guest

    Hey guys

    Is it possible to remove vlan 1 from a dot1q trunk on a C3524XL with
    12.0(5)WC9a? Just using 'switchport trunk allowed vlan remove 1' doesn't
    work for VLAN 1 (+1002-1005) but all other VLAN's.

    I have also changed the native vlan to another VLAN but that didn't help.

    Is there maybe some workaround? Or do you have to change your management
    VLAN to something other than 1 to not have your management traffic out
    on the trunk?

    Regards
     
    Thomas Novin, Sep 29, 2004
    #1
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  2. Thomas Novin

    Copulatus Guest

    VLAN 1 cannot be removed from a trunk. It is seen as the management
    VLAN and as a result, cannot be pruned...
     
    Copulatus, Oct 1, 2004
    #2
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  3. Thomas Novin

    vipergg Guest

    The simpple answer is no you cannot remove vlan 1 from the trunk as
    it is the default vlan . Some of the newer Catos switches do allow
    you to take them off the trunk but I don't believe you can on your
    switch .
     
    vipergg, Oct 1, 2004
    #3
  4. Thomas Novin

    Ivan Ostreš Guest

    Just out of curiosity, which are those "new catos switches" that can
    remove vlan 1 off the trunk?
     
    Ivan Ostreš, Oct 1, 2004
    #4
  5. Hello, Ivan!
    You wrote on Fri, 1 Oct 2004 19:40:01 +0200:

    ??>> The simpple answer is no you cannot remove vlan 1 from the
    ??>> trunk as it is the default vlan . Some of the newer Catos
    ??>> switches do allow you to take them off the trunk but I don't
    ??>> believe you can on your switch .
    ??>>
    IO> Just out of curiosity, which are those "new catos switches" that
    IO> can remove vlan 1 off the trunk?

    http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a0080094713.shtml
    ....
    In CatOS 5.4 and later, it has been possible to limit VLAN 1 from carrying user
    data and running STP by issuing the following command:
    clear trunk mod/port vlan 1

    This does not stop control packets being sent from switch to switch in VLAN 1,
    as seen with a network analyzer. No data will be forwarded, however, and STP
    will not be run over this link. Therefore, this technique can be used to break
    VLAN 1 up into smaller failure domains.

    Note: It is not currently possible to clear VLAN 1 trunks on 3500s and 2900XLs
    ....

    It's also possible to remove VLAN 1 on 4500 and 6500 series. I didn't try it on
    2950/3550 but I think only 2900XL and 3500XL is an exception now.

    With best regards,
    Andrey.
     
    Andrey Tarasov, Oct 1, 2004
    #5
  6. Thomas Novin

    Ivan Ostreš Guest

    Hi Andrey,

    that was exactly I was thinking of... you still can not force switch not
    to send packets using VLAN 1 (not user traffic thought) so since you
    have still "some" packets using VLAN 1 on a trunk from which VLAN 1 has
    been "removed" you actually didn't remove it...

    Funny, isn't it? :)
     
    Ivan Ostreš, Oct 2, 2004
    #6
  7. Hello, Ivan!
    You wrote on Sat, 2 Oct 2004 12:08:50 +0200:

    IO> that was exactly I was thinking of... you still can not force
    IO> switch not to send packets using VLAN 1 (not user traffic
    IO> thought) so since you have still "some" packets using VLAN 1 on a
    IO> trunk from which VLAN 1 has been "removed" you actually didn't
    IO> remove it...

    Well, the whole idea behind removing VLAN 1 from trunk is to get rid of
    campus-wide spanning-tree instance. If you turn off CDP, VTP and PAgP there will
    be no VLAN 1 traffic at all.

    With best regards,
    Andrey.
     
    Andrey Tarasov, Oct 2, 2004
    #7
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