MPLS-Enabled Applications: Emerging Developments and New Technologies

10.2. THE BUSINESS DRIVERS

The benefits of BGP/MPLS IP VPNs for both customers and providers have been discussed in Chapter 7. Because L3VPNs provide the customer with the abstraction of a private network, the expectation is to be able to support any type of application that would run in this private network. As applications relying on multicast become more widely deployed in the enterprise, support for multicast becomes a requirement for an increasing number of customer networks which rely on L3VPNs for their intersite connectivity.

The original multicast solution is documented in [DRAFT-ROSEN] and therefore often referred to as draft-rosen. Draft-rosen solved the problem of carrying multicast traffic between customer sites but suffered from various shortcomings, mostly in the scaling area. These problems become most apparent in deployments where (a) a large percentage of the L3VPN customers require support for multicast as well as unicast traffic and (b) the amount of multicast traffic is non-negligible compared to the unicast traffic (thus requiring traffic engineering in the provider's network). When the draft-rosen solution was initially proposed, neither of these two conditions was of concern. However, several factors drove the increase in multicast traffic in L3VPNs, thus creating the need for a new approach:

1. L3VPN deployments became successful and grew in size, increasing the number of VPNs that must be supported.

2. Applications relying on multicast, such as business IPTV, ...