Re: MPLS VPN

Hello,
The P routers do not participate in MPLS VPN (MPLS VPN, not
just MPLS), 
but participates in MPLS (just MPLS, not MPLS VPN).
In MPLS VPN you have at least two labels, one for switching
packets and 
one to identify VPN.
P only cares about the top label (the one used for
switching), and do 
not use the second label used to identifies VPN.
The second label is used by PE's to get the packet in the
right vrf/vpn.

The P router do not carry vpn routes, it only uses IGP
routes (in order 
to build LFIB)
CE-->PE(ingress router)-->P router-->P router--PE
router(Egress)-->CE is 
right.

Tell me if I am wrong (I am studying for CCIP...)



> Hi guys,
>          Iam confused with this.Iam doing ccnp.The
paragraph below says P
> router of mpls backbone doesn't participate in MPLS...
>
>
> "From the P router perspective, the MPLS VPN
backbone looks even
> simplerbthe P routers do not participate in MPLS VPN
routing and do not
> carry VPN routes."
>
> But in the book it also says under section "MPLS
VPNs and Packet
Forwarding"
> The two-level MPLS label stack satisfies these MPLS VPN
forwarding
> requirements:
>
> "" (The P routers perform label switching on
the LDP-assigned label toward
> the egress PE router).
> The egress PE router performs label switching on the
second label (which
the
> router has previously assigned), and either forwards
the IP packet toward
> the CE router or performs another IP lookup in the VRF
table that the
second
> label in the stack points to.""
>
> and there is a diagram showing mpls vpn frame going
from CE in left hand
> side to PE(ingress router) to P router of MPLS VPN
backbone to another P
> router and to PE(egress router) to CE
>
> like this 
>  CE-->PE(ingress router)-->P router-->P
router--PE router(Egress)-->CE.
>
>
> sorry for too long question or it may not be problem
for some cisco lovers
> 
>
>
> thank you
>
> Kind regards
>
> Tika




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