Methods, apparatus and data structures are provided for managing multicast IP flows. According to one embodiment, a memory of a router has stored therein a data structure, which includes information relating to multicast sessions being handled by the router and including a first pointer for each multicast session, at least one chain of blocks of second pointers and one or more TCBs. Each first pointer points to a chain of blocks of second pointers. Each second pointer corresponds to an OIF of the router participating in the multicast session defined by the first pointer and defines how many times packets associated with the multicast session are to be replicated. The TCBs are configured to store control information relevant to processing or routing packets. Each second pointer points to a TCB and each TCB identifies the OIF out which packets of the multicast session are transmitted from the router.