DELAYED UPDATING OF FORWARDING DATABASES FOR MULTICAST TRANSMISSIONS OVER TELECOMMUNICATIONS NETWORKS

摘要

A switch (110R.3) uses a forwarding database (140F) 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.

主权项

1. A method comprising operating a first switch which is one of a first set of network nodes which are network switches, wherein the first switch is operable to communicate with nodes of the first set and also with nodes of a second set which is a set of one or more network nodes, wherein each node of the second set is not in the first set;
wherein the first switch is operable to classify an incoming multicast data packet as being of a first type or a second type, wherein: the first type comprises multicast data packets received from one or more nodes of the first set; the second type comprises multicast data packets received from one or more nodes of the second set; wherein the first switch uses a forwarding database to make forwarding decisions; wherein operating the first switch comprises: the first switch receiving an indication for an additional recipient of data packets addressed to a multicast group, the additional recipient being in the second set; in response to the indication, the first switch provisioning the forwarding database to provide forwarding decisions for forwarding to the additional recipient of data packets of the first type, but the first switch not provisioning the forwarding database for data packets of a third type of data packets, wherein each data packet of the third type is also of the second type.