10.2.3.4 forwards all data packets for Server 10.1.3.8 to its default gateway. When a packet arrives at CE 2, it performs a longest-match route lookup and forwards the IPv4 packet to PE 2. PE 2 receives the packet, performs a route lookup in VRF Red, and obtains the following information. The initial MPLS label for the LSP from PE 2 to PE 1 User traffic is forwarded from PE 2 to PE 1 using MPLS with a label stack containing two labels. After creating the label stack, PE 2 forwards the MPLS packet on the outgoing interface to the first P router along the LSP from PE 2 to PE 1.
P routers switch packets across the core of the provider's backbone network based on the top label.
When PE 1 receives the packet, it pops the label creating a native IPv4 packet. Finally, PE 1 forwards the native IPv4 packet to CE 1, which forwards the packet to Server 10.1.3.8 at Site 1. There are no constraints on the address plan used by each VPN customer. The customer can use either globally unique or private IP address spaces. From the service provider's perspective, different customers can have overlapping address spaces.