Delayed updating of forwarding databases for multicast transmissions over telecommunications networks

Abstract

A switch (R.) uses a forwarding database (F) to forward multicast packets. The switch participates in a multicast protocol (e.g. PIM) with other switches, and also uses a snooping database (e.g. for IGMP snooping) to learn about local group members, i.e. members for which the router serves as a local multicast router (e.g. the local members do not participate in the multicast protocol). When the switch learns of a local member of a multicast group, the switch updates the snooping database but may or may not install the snooping information in the forwarding database. Thus, the forwarding database is not necessarily provisioned for locally sourced data packets addressed to the group until receipt of a locally sourced data packet addressed to the group. If no such packets are received, the forwarding database is not provisioned for such packets, and therefore its size is reduced. Other features are also provided.