Protocol-Independent Multicast: Difference between revisions

Revision as of 04:11, 4 September 2016

Revision as of 15:08, 30 March 2017

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* '''PIM Dense Mode''' (PIM-DM) uses [[dense multicast]] routing. It 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 |archiveurl=https://web.archive.org/web/20110614164202/http://www.multicasttech.com/faq/ |archivedate=2011-06-14}}</ref> See the PIM Internet Standard RFC 3973.

* '''Bidirectional 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. See Bidirectional PIM Internet Standard 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 amountnumber 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 RFC 3569.

PIM-SM is commonly used in [[IPTV]] systems for routing multicast streams between [[VLAN]]s, [[Subnetwork|Subnets]] or local area networks.<ref>{{cite web |url=https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Y.Sup16-201202-I!!PDF-E&type=items |title=Supplement on guidelines on deployment of IP multicast for IPTV content delivery |publisher=[[ITU-T]] |accessdate=2014-03-23}}</ref>