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Method of Doing Multicast Over Non-Multicast Capable MPLS-Based Layer3 VPNs Disclosure Number: IPCOM000004793D
Original Publication Date: 2001-May-29
Included in the Prior Art Database: 2001-May-29
Document File: 3 page(s) / 32K

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Vidya Narayanan: AUTHOR


Method of Doing Multicast Over Non-Multicast Capable MPLS-Based Layer3 VPNs

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Method of Doing Multicast Over Non-Multicast Capable MPLS-Based Layer3 VPNs By Vidya Narayanan


A Virtual Private Network (VPN) can be defined as customer connectivity on shared infrastructure with the same policies obtained in a private network. A VPN can be built using the internet or a service provider private IP, Frame Relay, or ATM infrastructure. VPNs enable business customers to experience the same security, priority, manageability, and reliability as they do in their private networks. The service provider networks on which the VPNs are deployed must be reliable, scalable, cost-effective and high-capacity networks. Further, these networks must be capable of meeting a wide range of customer requirements including security, QoS, and any-to-any connectivity. MPLS lends itself as a natural candidate for VPN deployment because of its true "multi-protocol" nature.

Future Motorola systems might be deployed using Virtual Private Networks (VPN) in place of leased lines (or even the whole core) so that we can outsource a part of the network from a service provider. This might be viewed as an efficient method of reducing recurring costs in our systems. MPLS-based VPNs seem to offer the maximum advantages when compared to other types of VPNs and most service providers are migrating towards an MPLS-based VPN. Multicast has become an important technology for CGISS systems. The current X-Zone architecture is based on IP Multicast and there is a good probability that we would need multicast for our future X-Zone and wideband systems as well.


If the VPN deployed is a layer2 VPN, multicast can be done over that without a problem. However, layer2 VPNs are not as attractive as layer3 VPNs due to several reasons beyond the scope of this writing. Layer3 VPNs provide several advantages, especially since we now make use of the layer3 routing information inside the provider's network to ensure the best path, etc. MPLS-based layer3 VPNs provide the added benefits of using MPLS (like Traffic Engineering, QoS, etc.). In addition, MPLS-based layer3 VPNs provide the same level of security as a layer2 VPN. Consequently, MPLS is becoming the widely accepted choice of service providers for deploying VPNs.

If the service provider network does not provide multicast support for MPLS-based VPNs, there is no current solution for doing multicast over such a VPN. It would be possible to do it if we have a layer2 VPN. However, a layer2 VPN has a lot of drawbacks as mentioned above. There is no method to currently provide multicast over a non-multicast capable layer 3 VPN. Moving to a layer2 VPN would mean that we would not be able to fully leverage off the Traffic Engineering and Fast Convergence capabilities of MPLS-based Layer3 VPNs.


It is possible to provide multicast service over an MPLS-based VPN by having boxes at the Customer Edge (CE) that are capable of...