Delayed updating of forwarding databases for multicast transmissions over telecommunications networks

A method comprising operating a first switch which is one of a plurality of switches interconnected and configured to provide one or more multicast distribution trees to distribute multicast packets, the first switch comprising one or more first interfaces and one or more second interfaces, the first and second interfaces being operable to receive multicast data packets, each first interface being operable to receive multicast data packets in at least one said multicast distribution tree, each second interface being operable to receive multicast data packets that do not arrive in any said multicast distribution tree but are to be forwarded by the first switch to a root of at least one said multicast distribution tree, the first switch using a forwarding database to make forwarding decisions for the multicast packets, the first switch using a first database to store information on how multicast data packets received on the one or more second interfaces are to be forwarded, the first switch being operable to update the forwarding database from the first database;

• wherein operating the first switch comprises:
• receiving, on one or more second interfaces, one or more first indications for one or more new members of one or more multicast groups;
• in response to the one or more first indications:
• (a) performing “first provisioning”, wherein the first provisioning is provisioning the forwarding database to provide forwarding decisions for forwarding to the one or more members of data packets addressed to the corresponding one or more multicast groups and received on the one or more first interfaces in at least one said multicast distribution tree;
• (b) storing, in the first database, one or more second indications that multicast data packets received on the one or more second interfaces and addressed to the one or more multicast groups are to be forwarded to the corresponding one or more new members to reach the one or more new members without going through any said multicast distribution tree and without going through any one of said switches other than the first switch;
• (c) executing a predefined policy on performing “second provisioning”, wherein the second provisioning is updating the forwarding database from the first database to reflect the one or more second indications, the predefined policy comprising one or more instances when performance of at least some of the second provisioning is contingent on one or more later events;
• wherein for at least one first indication, the corresponding one or more later events comprise receiving, on a second interface, a data packet addressed to the corresponding multicast group, and in at least one said instance, the second provisioning is not performed until occurrence of the corresponding one or more later events.

A first switch which is a network switch configured to operate as one of a plurality of switches configured to provide one or more multicast distribution trees to distribute multicast packets, the first switch comprising one or more first interfaces and one or more second interfaces, the first and second interfaces being operable to be configured to receive multicast data packets, each first interface being operable to receive multicast data packets in at least one said multicast distribution tree, each second interface being operable to receive multicast data packets that do not arrive in any said multicast distribution tree but are to be forwarded by the first switch to a root of at least one said multicast distribution tree, wherein the first switch comprises a data plane configured to use a forwarding database to make forwarding decisions for the multicast packets, and comprises a control plane configured to use a first database to store information on how multicast data packets received on the one or more second interfaces are to be forwarded, the first switch being configured to update the forwarding database from the first database;

• wherein the first switch is operable to perform operations of:
• receiving, on one or more second interfaces, one or more first indications for one or more new members of one or more multicast groups;
• in response to the one or more first indications:
• (a) performing “first provisioning”, wherein the first provisioning is provisioning the forwarding database to provide forwarding decisions for forwarding to the one or more members of data packets addressed to the corresponding one or more multicast groups and received on the one or more first interfaces in at least one said multicast distribution tree;
• (b) storing, in the first database, one or more second indications that multicast data packets received on the one or more second interfaces and addressed to the one or more multicast groups are to be forwarded to the corresponding one or more new members to reach the one or more new members without going through any said multicast distribution tree and without going through any one of said switches other than the first switch;
• (c) executing a predefined policy on performing “second provisioning”, wherein the second provisioning is updating the forwarding database from the first database to reflect the one or more second indications, the predefined policy comprising one or more instances when performance of at least some of the second provisioning is contingent on one or more later events;
• wherein for at least one first indication, the corresponding one or more later events comprise receiving, on a second interface, a data packet addressed to the corresponding multicast group, and in at least one said instance, the second provisioning is not performed until occurrence of the corresponding one or more later events.