04-09-2008 04:41 AM
Hi There,
can anybody throw some light on how vpn labels assigned and exchanged between PE routers for vrf subnets since P routers only knows about global subnets?
Regards,
Rajesh
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04-09-2008 04:56 AM
Rajesh,
The VPN labels are exchanged between PE via the mBGP VPNv4 updates. As you indicated, the P routers are completely oblivious of these updates, unless of course a P router is used as a route reflector, in which case it will obviously need to hold the VPNv4 prefixes (control plane only).
The MPLS packet switching from the ingress to the egress PE is performed based solely on the outside label also known as IGP label.
Regards,
04-09-2008 04:56 AM
Rajesh,
The VPN labels are exchanged between PE via the mBGP VPNv4 updates. As you indicated, the P routers are completely oblivious of these updates, unless of course a P router is used as a route reflector, in which case it will obviously need to hold the VPNv4 prefixes (control plane only).
The MPLS packet switching from the ingress to the egress PE is performed based solely on the outside label also known as IGP label.
Regards,
08-28-2008 02:51 AM
can u have any diagram which clearly shows how mpls vpn label are exchanged. I dont have any problem if u can provide me hand made diagram also
08-28-2008 05:10 PM
09-03-2008 02:19 AM
Hi,dude
vpnv4 lables only knows at PE routers and these exchanged with other PEs by MP-BGP.
P router don't know about these vpnv4 lables. So in common MPLS VPN environment, PE router assign 2 lable to packet so called vpnv4 lable & vpn lable. only P router lookup outermost lable and switch packet to another PE.
Once another PE received lable it look up vpnv4 label and switch the packet to correct VRF.
HTH
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