MPLS Configuration on Cisco IOS Software

Case Study 5: Implementing Dynamic Layer 3 VPNs Using mGRE Tunnels

This case study delves into the implementation of dynamic Layer 3 VPNs using mGRE tunnels. Implementation of mGRE tunnels creates a multipoint tunnel network as an overlay to the IP backbone that interconnects the PE routers to transport VPN traffic. The multipoint tunnel uses BGP to distribute VPNv4 information between PE routers. The advertised next hop in BGP VPNv4 triggers tunnel endpoint discovery. Dynamic L3 VPN implementation over mGRE tunnels provides the ability for multiple SPs to cooperate and offer a joint VPN service with traffic tunneled directly from the ingress PE router at one service provider directly to the egress PE router at a different SP site.

When implementing ...