Re: Native vlan and allowed vlan

Two important types of traffic are cleared from VLAN 1. The first is user
data, meaning if, for

example, you have users on Switch-A in VLAN 1 and users in Switch-B in VLAN
1, users cannot communicate if VLAN 1 is cleared from a

trunk between Switch-A and Switch-B. The second type of traffic that is
cleared is spanning-tree BDPU traffic, which is the important

feature of VLAN 1 trunk clearing. Clearing VLAN 1 from a trunk reduces the
size of the VLAN 1 spanning-tree domain, which allows

network designers to control the extent of the VLAN 1 spanning-tree topology
and ensures the stability of larger networks

Rgrds
Ankur

On 9/1/09, Iwan Hoogendoorn <iwan_at_ipexpert.com> wrote:
>
> Hi Julio,
>
> This depends on your IOS version and platform you are using.
> Anyways you can accomplish that VLAN 1 is not allowed on the trunk on
> specific platforms.
> But as the rest stated you may get messages that the native VLAN is
> not the same ... bla bla bla
> You can disable these messages by disabeling CDP under the interface.
>
>
> --
> Regards,
>
> Iwan Hoogendoorn
> CCIE3 #13084 (R&S / Security / SP)
> Sr. Support Engineer IPexpert, Inc.
> URL: http://www.IPexpert.com
>
> On Tue, Sep 1, 2009 at 10:02 AM, Julio Carrasco<julio.carrasco_at_ya.com>
> wrote:
> > Hi guys,
> >
> > Just one small question.
> >
> > If I leave the default native vlan (vlan 1), configured on a trunk, and I
> > issue the "switchport trunk allowed vlan 21,43",
> > Does the traffic for vlan 1 still crossing the trunk?, or is blocked by
> the
> > swithport trunk allowed vlan?
> >
> > Thanks in advance.
> > Best regards.
> >
> >
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> >
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> >
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>
>
>
> --
> Regards,
>
> Iwan Hoogendoorn
> CCIE #13084 (R&S / Security / SP)
> Sr. Support Engineer IPexpert, Inc.
> URL: http://www.IPexpert.com
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
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>
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>

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