Delivering L3VPNs over IP
L3VPNs allow the provider to extend its customer's private IP network over the provider's backbone. When delivering an L3 service, the service provider is normally involved in the assignment and management of a pool of IP addresses allocated to its customer. This is typical of carriers that are also ISPs offering Internet services or carriers offering IP multicast services and so on. L3VPNs can be delivered via GRE tunnels or MPLS L3VPNs.
L3VPN services over IP have traditionally been done using generic routing encapsulation (GRE) tunnels, which allow the encapsulation of IP packets inside IP packets. GRE-based VPNs are CE-based VPNs. A network hierarchy can be maintained in which an enterprise that has, ...