From: Ivan (ivan@iip.net)
Date: Thu Oct 13 2005 - 06:29:06 GMT-3
Some nice trick appear with existing native vlan.
int f0/0
ip add 1.1.1.1 255.255.255.0
int f0/0.101
encap dot1q 101
ip add 101.101.101.101 255.255.255.0
int f0/0.202
encap dot1q 202
ip add 202.202.202.202 255.255.255.0
Untagged frame can be accepted by interface (not sub-interface)
On Wednesday 12 October 2005 22:41, Ed Lui wrote:
> Larry,
>
> In other words, vlan 1 is the default native vlan. Even if I shut it
> down, it is still there in shutdown state. In the meantime, frames
> going thru the trunk port are all tagged and the router doesn't care
> if there are untagged frames as long as the router is told which tag
> goes on which sub-interface.
>
> In conclusion, native vlan is there all the time even it is shutdown
> and not being used. Native vlan(untagged) is not to be defined
> mandatory just like ISL.
>
> Correct ?
>
> On 10/12/05, Larry Letterman (lletterm) <lletterm@cisco.com> wrote:
> > Ed,
> >
> > it will still assign a native vlan as 1 per the default, even if you
> > shut vlan 1 down....and all non-tagged data will still use that...
> >
> >
> > Larry Letterman
> > INS-NW-WEST
> > Cisco Systems
> >
> >
> >
> >
> > ________________________________
>
> From: Ed Lui [mailto:edwlui@gmail.com]
>
> > Sent: Wednesday, October 12, 2005 11:39 AM
> > To: Larry Letterman (lletterm)
> > Cc: ccielab@groupstudy.com
> > Subject: Re: DOT1Q NATIVE VLAN STANDARD or NON-STANDARD
> >
> >
> >
> >
> >
> >
> > Larry,
> >
> > What if I set up HSRP and sub interfaces on both routers without defining
> > native and vlan 1 shutdown ? In my router on a stick scenario, it worked.
> > Any idea ?
> >
> >
> > R1(vlan3,8)===========|vlan3,8(dot1q trunk w/o native)
> >
> > |---------------3550EMI------------
> > |---
> >
> > R2(vlan3,8)===========|vlan3,8(dot1q trunk w/o native)
> >
> > Thanks,
> > Ed Lui
> >
> > On 10/12/05, Larry Letterman (lletterm) <lletterm@cisco.com> wrote:
> > > Ed,
> > >
> > > Set up two routers with dot1q sub-interfaces...connect the FaEthernets
> > > to a 3550/3750,
> > > Set the trunk ports for that switch so that the data vlan is the native
> > > vlan. Setup the hsrp
> > > On the routers, and you'll see that the native vlan being set
> > > incorrectly will alter the
> > > Opeartion of things..you can always leave it to the default of vlan 1..
> > >
> > >
> > >
> > > Larry Letterman
> > > INS-NW-WEST
> > > Cisco Systems
> > >
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > > Ed Lui
> > > Sent: Wednesday, October 12, 2005 11:03 AM
> > > To: ccielab@groupstudy.com
> > > Subject: DOT1Q NATIVE VLAN STANDARD or NON-STANDARD
> > >
> > > Hi group,
> > > I have no luck finding out why we need native vlan in dot1q. I
> > > understand that native vlan should be defined on a trunk port. I came
> > > across a router on a stick lab scenario, which I did not define the
> > > native vlan and it is still working fine. Read through the dot1q
> > > standard on ieee.org<http://ieee.org>but still can not figure out my
> > > question.
> > > So, what is the difference between having a native and not having a
> > > native vlan defined ? The only thing I can think of is, tagged frame
> > > can carry QoS information. Other than that, what is the benefit or
> > > difference between tagged and untagged frames ? Why define a native ?
> > >
> > > Thanks in advance for any help or hint,
> > >
> > > Ed Lui
> > >
> > >
> > > TRUNK W/O NATIVE VLAN
> > > 2621=============================3550
> > >
> > > _______________________________________________________________________
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
-- Ivan
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