DISTRIBUTED GENERATION OF HIERARCHICAL MULTICAST FORWARDING STRUCTURES

In general, techniques are described in which packet replicators of a network device cooperate to generate a distributed hierarchical forwarding structure that the packet replicators then use to replicate and forward multicast packets to multiple output interfaces. For example, packet forwarding engines (PFEs) of a router each receive a new list of interfaces for a multicast packet stream. The PFEs individually construct a hierarchical forwarding structure based on the interface list. The hierarchical forwarding structure specifies interrelationships among the PFEs, which occupy nodes within the hierarchy. Each child PFE determines from the hierarchical forwarding structure the identity of a parent PFE and issues a token, constituting forwarding state for the distributed hierarchical forwarding structure, to the parent PFE. The parent PFE uses the token to identify packets of the multicast traffic to the child PFE during replication and forwarding of multicast packets proceeding according to the hierarchical forwarding structure.