Method, apparatus and system for forwarding data under protocol independent multicast dual join

A router, configured to forward data under protocol independent multicast dual join, comprising a main incoming interface and a backup incoming interface, wherein

• when the main incoming interface is up, the router forwards multicast data, sent by a neighboring router, received from the backup incoming interface to the main incoming interface in a join state without forwarding the multicast data to an interface that is in a join state and is different from the main incoming interface and the backup incoming interface;
• and
• when the main incoming interface is down, before selecting a new main incoming interface and/or backup incoming interface, the router forwards the multicast data sent by the neighboring router back to the neighboring router via the backup incoming interface.

A network system, comprising routers under protocol independent multicast dual join, wherein

• a first router of the routers is configured to, when a main incoming interface of the first router is up, forward multicast data received from a backup incoming interface of the first router to the main incoming interface in a join state without forwarding the multicast data to an interface that is in a join state and is different from the main incoming interface and the backup incoming interface;
• and when the main incoming interface is down, before selecting a new main incoming interface and/or backup incoming interface, forward the multicast data sent by the neighboring router back to the neighboring router via the backup incoming interface.