Netgear XCM8806 Chassis User Manual - Page 729

NETGEAR 8800 User Manual Note: This feature is supported at and above the license level listed for this feature in the license tables in Appendix A, XCM8800 Software Licenses. Using PIM-SM, the router sends a join message to the rendezvous point (RP). The RP is a central multicast router that is responsible for receiving and distributing the initial multicast packets. You can configure a dynamic or static RP. When a router has a multicast packet to distribute, it encapsulates the packet in a unicast message and sends it to the RP. The RP decapsulates the multicast packet and distributes it among all member routers. When a router determines that the multicast rate has exceeded a configured threshold, that router can send an explicit join to the originating router. When this occurs, the receiving router gets the multicast directly from the sending router and bypasses the RP. Note: You can run either PIM-DM or PIM-SM per virtual LAN (VLAN). PIM Mode Interoperation A NETGEAR switch can function as a PIM multicast border router (PMBR). A PMBR integrates PIM-SM and PIM-DM traffic. When forwarding PIM-DM traffic into a PIM-SM network, the PMBR acts as a virtual first hop and encapsulates the initial traffic for the RP. The PMBR forwards PIM-DM multicast packets to the RP, which, in turn, forwards the packets to those routers that have joined the multicast group. The PMBR also forwards PIM-SM traffic to a PIM-DM network, based on the (*.*.RP) entry. The PMBR sends a (*.*.RP) join message to the RP, and the PMBR forwards traffic from the RP into the PIM-DM network. No commands are required to enable PIM mode interoperation. PIM mode interoperation is automatically enabled when a dense mode interface and a sparse mode interface are enabled on the same switch. PIM Source Specific Multicast PIM-SM works well in many-to-many multicasting situations. For example, in video conferencing, each participating site multicasts a stream that is sent to all the other participating sites. However, PIM-SM is overly complex for one-to-many multicast situations, such as multimedia content distribution or streaming stock quotes. In these and similar applications, the listener is silent and can know the source of the multicast in advance, or can obtain it. In these situations, there is no need to join an RP, as the join request can be made directly towards the source. Chapter 27. Multicast Routing and Switching | 729