This is a source specific Join and is noted as (S,G). For this purpose it starts to send Join messages towards MC source to nearest neighbor to that source according the MRIB. When the RP identifies that a new MC source started to send packets, it initiates an establishment of a native forwarding path from the DR of that source to itself. On the second stage the RP switches from tunneling of multicast packets from MC sources to forwarding native traffic. The RP decapsulates the packets and distributes them to all MC receivers along with the share tree. The DR next to the MC source extracts the packets from the data flow and tunnels them to the RP. Usually that tree is called a shared tree because it is created for any source for specific MC group G and is noted as (*,G).Īt that stage, MC senders can start sending MC data. Eventually the process converges when Join messages reach RP or a router that has already created that distribution tree. The next router continues to do the same. It starts to send periodic “Join” messages to the nearest PIM neighbor router towards the RP. When such request is received by the last hop router (a designated router) this router starts to build a distribution path from the RP. It can happen as a result of using one of the 元 protocols like MLD or IGMP, or by static configuration. The first stage of the multicast tree establishment starts when the MC receiver expresses desire to start receiving MC data.
Construction of a shared distribution tree. This tree is built around a special router called the rendezvous point (RP).MC tree construction contains three phases: MC data flows along with the reverse path of the PIM control. The primary role of MRIB is to determine the next hop for PIM messages. PIM relies on the underlying topology gathering protocols that collect unicast routing information and build multicast routing information base (MRIB). PIM builds and maintains multicast routing tables based on the unicast routing information provided by unicast routing tables that can be maintained statically or dynamically by IP routing protocols like OSPF and BGP. PIM protocol family includes PIM dense mode (PIM-DM), Bootstrap router (BSR) protocol, and PIM sparse mode (PIM-SM) and Bidirectional PIM (PIM-BIDIR)-both of which are not supported on Onyx. Those protocols are published in the series of RFCs and define different ways and aspects of multicast data distribution. Protocol independent multicast (PIM) is a collection of protocols that deal with efficient delivery of IP multicast (MC) data.
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