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
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=18691&t=18545
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