RE: switch trunk allow vlan except 1 (valid for not allowing

From: Scott Vermillion (scott_ccie_list@it-ag.com)
Date: Fri Nov 02 2007 - 18:02:41 ART


Hey Michael,

Actually, you bring to mind a good point: if the task called for some trunk
traffic to be untagged somewhere but all traffic to be tagged/encapsulated
elsewhere on that same box, you'd need to do dot1q for the untagged portion
and I guess ISL for the other. All I know of is to globally enable or
disable tagging of the native VLAN. There isn't a way to do it at interface
level is there?

Also, I just remembered from a recent CoD session that not allowing VLAN1 on
a trunk is simply "VLAN1 minimization"; it prevents user traffic from
traversing the trunk in VLAN1 but not control traffic. So you would still
have some untagged traffic with that approach.

Regards,

Scott

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
M_A_Jones@Dell.com
Sent: Friday, November 02, 2007 2:24 PM
To: alex.steer@eison.co.uk; ccielab@groupstudy.com
Subject: RE: switch trunk allow vlan except 1 (valid for not allowing
untagged packets across a trunk?)

INMHO

I would think in essence this is can be completed both ways, I would
think on the test you'd have to make sure the words used wouldn't
include default.If the term default was used Im sure you know ISL would
be your T protocol of choice.

Esentially all vlans are tagged either way using do1q native command.

Are you sure the question didn't state " All traffic transvering the
trunk should be tagged" ??

Michael Jones
Network Engineer
Global Network Operations
Dell Inc.
512.723.3268

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Alex Steer
Sent: Friday, November 02, 2007 3:05 PM
To: CCIE Group Study CCIE Group Study
Subject: switch trunk allow vlan except 1 (valid for not allowing
untagged packets across a trunk?)

Hi,

Can anyone give their thoughts on this please?

Question:-

"All traffic sent over these trunk links should be tagged with a VLAN"

Int fa0/7

Swi trunk encap dot

Swi mode trunk

Swi trunk native vlan 1 (for completeness)

Swi trunk allow vlan except 1

The solution to this question required the configuration of the trunk to
be ISL. Being thick I forgot ISL tags all packets. Do the above
solution solve the question?

I have a funny feeling I have asked this before J

Cheers

Alex



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