RE: Switchport trunk allow ?

Hi Vincent,

There seems to be a lot of misinformation on this topic. If you use the
switchport trunk allow command on a 3560 then you must permit all VLANs for
which you want switched traffic to pass. This includes the native VLAN.

If traffic is not permitted, it is denied.

The ONLY exceptions are for LINK-LOCAL CONTROL traffic, like DTP, VTP, CDP,
which will exit on VLAN 1, whether or not VLAN 1 is permitted, whether or
not VLAN 1 is the native VLAN.

Do not believe me, or others or documentation! Lab it up. If you find
something different please let me know.

Best regards,

Bob Sinclair CCIE 10427 CCSI 30427
CIERS2 Online Instructor
www.tinyurl.com/ciers2online

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Vincent Tay
> Sent: Saturday, October 23, 2010 10:55 PM
> To: Ccielab_at_groupstudy.com
> Subject: Switchport trunk allow ?
>
> Hi all,
>
> If i use the command switchport trunk allow, do i have to include the
> native
> vlan "switchport trunk allow vlan1,.... if vlan 1 is a native vlan in
> order
> to bring the trunk up?
>
> Regards
> Vincent Tay
>
>
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Received on Sun Oct 24 2010 - 11:09:52 ART