Re: where third label of stack comes to scenario?

The innermost label is for the network itself. The next label would be the
egress PE. And then finally your TE label which is outermost. Try the basic
scenario:

CE1---PE1---P---PE2---CE2

Create your MPLS VPN and then a tunnel from PE1 to PE2. If you have the
ability to capture traffic, I believe you will see 3 labels on the packets
from PE1 to P. I think you may see 3 labels in inter-AS MPLS VPN too...I
will have to check some captures that I have.

-hth

Bryan Bartik
CCIE #23707 (R&S), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com

On Tue, May 19, 2009 at 5:18 PM, jeremy co <jeremy.cool14_at_gmail.com> wrote:

> Hi,
>
> I have difficulty understanding where third label of MLPS is used?
>
> in traffic eng ,traffic goes through tunnel and forwarded base on LSP
> created by RSVP (first label) and if vpn scenario is involved ,then we
> second label of vpn will comes to play.
>
> I saw in some books that MTU should be set to 1512 in case of MPLS/VPN/TE
> scenario. But i couldn't see any third label imposed.
>
> This is my understanding.
>
> Please correct me If I'm wrong
>
>
> Jeremy
>
>
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