MPLS-Enabled Applications: Emerging Developments and New Technologies

10.7. CONCLUSION

The L3VPN solution cannot be complete without support for multicast traffic. Although the original PIM-based solution described in draft-rosen could carry VPN customer traffic over a shared provider infrastructure, this approach departed from the L3VPN unicast model and suffered from scaling limitations both in terms of the maximum number of mVPNs it could support and in terms of the efficiency with which it could carry traffic through the provider network. As L3VPN deployments grew in size and as bandwidth-intensive multicast applications such as IPTV grew in popularity, the need for a more scalable way to handle L3VPN multicast traffic became imperative.

As a result, the NG mVPN solution was developed in the IETF and first commercial implementations became available shortly afterwards. The defining features of the NG mVPN solution are (a) carrying PIM join/prune information across the provider network using C-multicast routes in BGP, (b) discovering mVPN membership information using BGP autodiscovery routes, (c) allowing any tunneling technique in the provider network and (d) supporting aggregation of traffic from multiple VPNs onto the same tunnel in the provider network. In a nutshell, the NG mVPN solution uses BGP for the control plane and allows flexibility in the technology used for the tunnels in the provider network, just like L3VPN unicast. This alignment of unicast and multicast enables the reuse of solutions from the unicast domain for multicast, as ...