RE: dot1q tunnel mode

From: zesty@usa.com
Date: Sat Feb 10 2007 - 11:20:17 ART


Native vlan's packet going thru the dot1q-tunnel will not get a tag as
default. Remember to add the global command "vlan dot1q tag native" to
take care this situation. Tom

  ----- Original Message -----
  From: "Du, Jianbo"
  To: "John Jones" , ccielab@groupstudy.com
  Subject: RE: dot1q tunnel mode
  Date: Fri, 9 Feb 2007 09:23:40 -0700

  Native vlan had not been tagged. But if the packet income with
  untagged
  it will be tagged native vlan's ID when switch send the packet out
  via
  trunk port.

  Regards,
  Jerry
  -----Original Message-----
  From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
  Of
  John Jones
  Sent: Friday, February 09, 2007 10:30 PM
  To: ccielab@groupstudy.com
  Subject: Re: dot1q tunnel mode

  As a follow-up question, since dot1q traunking is used by the
  customer
  to
  get vlans to the provider, what happens to the native vlan? Is it
  tagged
  by
  the provider with no customer inside tag and transmitted like all
  others
  tagged vlans?

  John

  On 2/7/07, Sree N wrote:
>
> The CDP and VTP part is not entirely true. Consider using L2
  protocol
> tunneling for this purpose. Otherwise even with dot1q tunneling VTP
  and
> CDP
> frames will be terminated... not tunneled.
>
> On 2/5/07, Alex Ouraev wrote:
> >
> > Think about this from the service provider's perspective. You
  need
  to
> > carry
> > customer vlans/cdp/vtp unchanged between sites. How would you do
  that
> w/o
> > any knowledge as to how your customer does vlans. The answer is
  to
> > encapsulate it again into your own packet with your own tag at
  the
> source
> > switch, then carry it over to the destination customer site,
> de-capsulate
> > if
> > you may and spit out unchanged! I don't know who came up with
  this
  idea,
> > but
> > it's simple and brilliant to me... :)
> >
> > HTH
> >
> > Alex
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
  Behalf
  Of
> > Mohammad Saeed
> > Sent: Monday, February 05, 2007 1:07 PM
> > To: Cisco certification
> > Subject: dot1q tunnel mode
> >
> > Hi Evereybody,
> >
> > When we configure this on an interface on 3550 switch:
> >
> > switchport trunk encapsulation dot1q
> > switchport mode trunk
> >
> > that interface will tag all the frames coming from respective
  vlans
> > except the native vlan.
> >
> > But when we create dot1q tunnel and we configure on one interface
  that
> > is connected to Customer site to provide dot1q tunneling:
> >
> > switchport mode dot1q-tunnel
> > switchport access-vlan 1000
> >
> > Now as this port will be receiving traffic from multiple vlans,
  will
> > this interface tag all traffic with VLAN ID 1000 (theoratically
  it
> > shall not as we are not giving switchport trunk encapsulation
  dot1q)
> > or leave the traffic tagged with its original vlan. I am not
  clear
  in
> > what format this interface will receiving the traffic, will that
  be
> > normal ethernet frame or ethernet frame tagged with vlan id using
> > dot1q encapsulation. If any one can expalin a little bit, I will
> > appreciate that.....
> >
> > To me it looks like, all traffic will already be encapsulated
  using
> > dot1q and this interface will mark those frames with VLAN ID 1000
  and
> > will pass on to other end of dot1q tunnel.....
> >
> > Regards,
> >
> > Mohammad Zahed Saeed
> >
> >
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