VPRN is an IP/MPLS Layer 3 VPN Service. So, it uses the same Labels used in IP/MPLS. In MPLS and VPLS articles we have talked about MPLS Labels. Here, we will explain these Labels again for VPRN Service too.
Basically, VPRN uses two MPLS labels. These MPLS labels are:
• Outer Label (Transport, LSP Label)
• Inner Label (Service, VPN Label)
Outher Label is the Transport/LSP Label. Swap process is done with this label in the Service Provider Network. In each hop, it is changed.This label is used for used in end-to-end LSPs. So it is also called LSP Labels. And used between PE devices.
Inner Label is the Service/VPN Label. In Service Provider Network it remains unchanged. It is used by PE routers to determine the VPRN service. The other name of this label is VPN Label. It identifies the specific customers and determine the destination of L3 VPN (VPRN) Service.
These Labels are assigned at the PE Router. And in the Service Provider Core, only Outher Label is swapped. At the PEs, according to Service Labels, VPRN Service is determined.