I should have stuck to my original statement that the router would have to
be siting in the middle of a Layer 2 topology (i.e. a bridged network with
the router doing bridging). Thanks for the update.
A router (doing routing, not bridging) divides up VTP domains then. I guess
that's a good thing as long as you realize that this is the case.
Priscilla
At 05:26 PM 9/5/01, Sasa Milic wrote:
>Since VTP uses only VLAN 1, that means that VTP messages won't
>be passed from one subinterface to another, on the same trunk,
>since you can have only one subinterface assigned to VLAN 1.
>
>Regarding passing VTP messages from one trunk to another ...
>
> From http://www.cisco.com/warp/public/473/40.html:
>
> "The Catalyst 4908G-L3 does not support several Layer 2-oriented
> protocols, such as VTP, DTP, and PAgP, found on other Catalyst
> switches"
>
>Also:
>
> "In this example, the Catalyst 3512XL switches are configured in
> VTP transparent mode because a VTP domain cannot be extended across
> the Catalyst 4908G-L3."
>
>
>I would say that routers, as L3 devices, don't propagete VTP messages
>from one trunk to another.
>
>
>Sasa
>
>
>
>Priscilla Oppenheimer wrote:
> >
> > VTP advertisements are sent to a data-link-layer multicast
> > 01-00-0C-CC-CC-CC. The SNAP type is 2003 which distinguishes the frame
from
> > other Cisco frames that use that multicast (CDP and DISL, for example).
> >
> > As I said before, the router would have to be sitting in the middle of a
> > Layer-2 topology. For example, a one-armed router would pass VTP from one
> > subinterface to another, wouldn't it??
> >
> > I'm just trying to explain the statement from a CIT book about the router
> > being in VTP transparent mode, which was the original question. Perhaps
> > someone else has more details.
> >
> > Priscilla
> >
> > At 06:29 PM 9/5/01, Jeff Smith wrote:
> > >Does a VTP advertisement have a layer 3 address? I thought these were
> > >only heard within a broadcast domain. How does the router know who to
> > >pass these to on the other side?
> > >
> > >
> > >>From: "Priscilla Oppenheimer"
> > >>Reply-To: "Priscilla Oppenheimer"
> > >>To: [EMAIL PROTECTED]
> > >>Subject: Re: does vtp can span the router [7:18545]
> > >>Date: Wed, 5 Sep 2001 13:51:37 -0400
> > >>
> > >>A VTP transparent device does not advertise its VLAN configuration and
>does
> > >>not synchronize its VLAN configuration based on received
advertisements.
> > >>However, VTP-transparent devices do forward received VTP advertisements
>to
> > >>other devices.
> > >>
> > >>I can imagine a situation where a router with VLANs implemented is
>sitting
> > >>in the middle of a Layer 2 topology and you want the router to be in
VTP
> > >>transparent mode so that it passes VTP advertisements onto switches on
>the
> > >>other side of it. It doesn't seem like a very good design, but it could
> > >>happen.
> > >>
> > >>Priscilla
> > >>
> > >>At 10:19 AM 9/5/01, Guest wrote:
> > >> >I believe it means that the router will not listen to the vtp
messages.
> > >>It
> > >> >will also not pass them along- it is strictly layer 2.
> > >> >pass them along,you mean just transfer it ,right?but i don't know
where
> > it
> > >> >go,see my
> > >> >last message,i dont
> > >> >know which vlan can carry vtp,or like cdp-a purely layer 2 protocol,
> > >> >does vtp indepent of vlan,it runs on native vlan??
> > >> >i dont find ways to prove it.
> > >> >anyway ,thanks a lot
> > >>________________________
> > >>
> > >>Priscilla Oppenheimer
> > >>http://www.priscilla.com
> > >_________________________________________________________________
> > >Get your FREE download of MSN Explorer at
http://explorer.msn.com/intl.asp
> > >
> >
> > ________________________
> >
> > Priscilla Oppenheimer
> > http://www.priscilla.com
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=18700&t=18545
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