Overview of IP Multicasting

Multicast protocols allow a group or channel to be accessed over different networks by multiple stations (clients) for the receipt and transmission of multicast data.

Distribution of stock quotes, video transmissions such as news services and remote classrooms, and video conferencing are all examples of applications that use multicast routing.

RUCKUS devices support the Protocol-Independent Multicast (PIM) protocol, along with the Internet Group Membership Protocol (IGMP).

PIM is a broadcast and pruning multicast protocol that delivers IP multicast datagrams. This protocol employs reverse path lookup check and pruning to allow source-specific multicast delivery trees to reach all group members. PIM builds a different multicast tree for each source and destination host group.

Security Enhancement for IGMP

A security enhancement was made to IGMPv2 to comply with the following recommendation of RFC 2236: “Ignore the Report if you cannot identify the source address of the packet as belonging to a subnet assigned to the interface on which the packet was received.”

Note: When used in applications such as IP-TV (or any multicast application in general), the administrator should ensure that the set-top box (or multicast client) is configured on the same subnet as the virtual Ethernet interface configured on the device. This is typically the case, but is emphasized here to ensure correct operation. Without this configuration, IGMP messages received by the device are ignored, which causes an interruption in any multicast traffic directed towards the set-top box (multicast client).
Parent topic: IPv4 Multicast Protocols