TECHNICAL FIELD

The present technology pertains to multicast routing, and more specifically to implementing redundant multicast trees with fast recovery for multicast routing.

BACKGROUND

Traditional Internet Protocol (IP) communication allows a host to send packets to a single destination through unicast transmission or broadcast packets to an entire network segment through broadcast transmission. In addition, IP multicast technologies allow a host to send packets to a subset of hosts as a group or multicast transmission. Unicast transmissions use unicast addresses to send packets to single destinations associated with the unicast addresses. Broadcast transmissions use broadcast addresses to send packets to entire network segments or subnetworks. Multicast transmissions use multicast addresses to send packets to subsets of hosts configured as members of respective multicast groups. The members of a multicast group can reside on a same network or different networks.

IP multicast can conserve bandwidth by reducing traffic through simultaneous delivery of a stream of information to numerous recipients. Typically, multicast packets are replicated at a point where paths diverge using multicast protocols such as Protocol Independent Multicast (PIM), thereby delivering source traffic to multiple receivers without burdening the source or receivers and while utilizing a limited amount of network resources. Not surprisingly, IP multicast has gained considerable popularity as demand for multicast traffic continues to grow. For example, IP multicast is increasingly implemented in a wide variety of applications such as, for example, video conferencing, enterprise communications, and distribution of software and information.

At the same time, IP multicast can be significantly complex to implement and despite its numerous benefits, current IP multicast solutions face difficult challenges that can negatively impact the cost, performance and stability of multicast deployments. For example, in multicast deployments, multicast-capable routing devices use a multicast routing protocol to build a distribution tree for each multicast group. The distribution tree represents the multicast path(s) or state and allows sources to send packets to receivers. The distribution tree is updated periodically as nodes join or leave the multicast group or the topology changes. Moreover, a single point of failure can affect the distribution tree, requiring the network to reconstruct or repair the distribution tree. However, the process of updating or reconstructing the distribution tree can take time, which can cause disruption in multicast services and communications until the process completes and the network converges. The process also involves a significant amount of network communications, often including duplicate traffic. This traffic can significantly burden the network, thereby increasing cost and reducing network and service performance.

