IGP Weight Setting in Multimedia IP Networks

With more service providers making considerable investments to roll out multimedia services using IP technology, live TV distribution on IP network is expected to grow impressively over next few years. To make efficient use of IP network infrastructure, service providers use multicast to transmit broadcast video content to the receiving nodes while simultaneously using unicast to transport other services on the same network, such as video on demand (VoD), high-speed Internet (HIS) etc. How to engineer different traffic flows on the same network to avoid traffic congestion becomes a major design issue. Although the service traffic flows are from source to receivers, the IP multicast tree is calculated using IGP shortest path from the receivers to the source (backwards from the flow), while the unicast path is calculated from the source to the receivers (same direction as the flow). To minimize congestion, we take advantage of this property and propose an algorithm to tune IGP link weights (such as OSPF) such that the traffic flows for multicast and unicast don´t overlap. This proposal provides a natural way for service providers to use the spare capacity on the opposite direction of multicast traffic flow to roll out additional services in the same IP networks without impacting existing multicast services.