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Ryan Max B (talk | contribs) Added case for IGMPv3 source-specific join |
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* '''PIM Dense Mode''' (PIM-DM) implicitly builds shortest-path trees by flooding [[multicast]] traffic ___domain wide, and then pruning back branches of the tree where no receivers are present. PIM-DM is straightforward to implement but generally has poor scaling properties. The first multicast routing protocol, [[DVMRP]] used dense-mode multicast routing.<ref>{{cite web |url=http://www.multicasttech.com/faq/ |title=Frequently Asked Questions (FAQ) File for Multicasting |publisher=Multicast Tech |archive-url=https://web.archive.org/web/20110614164202/http://www.multicasttech.com/faq/ |archive-date=2011-06-14}}</ref> See RFC 3973.
* '''Bidirectional PIM''' (Bidir-PIM) explicitly builds shared bi-directional trees. It never builds a shortest path tree, so may have longer end-to-end delays than PIM-SM, but scales well because it needs no source-specific state.<ref name="Cisco Multicast"/>{{rp|70–73}} See RFC 5015.
* '''PIM Source-Specific Multicast''' (PIM-SSM) builds trees that are rooted in just one source, offering a more secure and scalable model for a limited number of applications (mostly broadcasting of content). In SSM, an IP datagram is transmitted by a source S to an SSM destination address G, and receivers can receive this datagram by subscribing to channel (S,G). See informational
PIM-SM is commonly used in [[IPTV]] systems for routing multicast streams between [[VLAN]]s, [[
==Versions==
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* Whether they arrive encapsulated or natively, the RP forwards the source's de-capsulated data packets down the RP-centered distribution tree toward group members.
* If the data rate warrants it, routers with local receivers can join a source-specific, shortest path, distribution tree, and prune this source's packets off the shared RP-centered tree.
* Where a router's local receivers are only interested in packets from a specific source within a multicast group, the router may skip joining the RP centered shared tree and jump straight to joining the source-specific shortest path tree.
* For low data rate sources, neither the RP, nor last-hop routers need join a source-specific shortest path tree and data packets can be delivered via the shared RP-tree.
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