385:
a Prune on their RPF interface if they don't need the multicast stream. Only one such Prune is sent, at the time of the transition to having no interfaces in the
Outgoing Interface List (OILIST). The LAN Prune receiver delays acting on it for 3 seconds, so that if another LAN router still needs the multicast stream, it can send a PIM Join message to counteract (cancel) the Prune. ("That router doesn't need it, but I still do!")
31:
138:(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 RFC 3569.
384:
to ensure that there are no loops for packet forwarding among routers that wish to receive multicast packets. When a data packet is received on a non-RPF interface, a mechanism is required to prevent loops. If the non-RPF interface is a LAN, an Assert message is sent. Non-Forwarder routers then send
376:
In older Cisco IOS releases, PIM-DM would re-flood all the multicast traffic every 3 minutes. This is fine for low volume multicast, but not higher bandwidth multicast packet streams. More recent Cisco IOS versions support a new feature called PIM Dense Mode State
Refresh, since 12.1(5)T. This
368:
directly connected to it. These neighboring routers further forward the data to their neighbors. When a router does not wish to receive this group's data (if no other neighboring PIM routers are present and no host is interested in the group), it sends a Prune message to indicate its lack of
348:
The basic assumption behind dense mode is that the multicast packet stream has receivers at most locations. Sparse mode assumes relatively fewer receivers. Dense mode is ideal for groups where many of the nodes will subscribe to receive the multicast packets, so that most of the
162:
There are two PIM versions. The versions are not directly compatible though may coexist on the same network. Network equipment may implement both versions. PIMv2 has the following improvements over PIMv1: A single RP is used per group. RP discovery is accomplished by a
377:
feature uses a PIM state refresh messages to refresh the Prune state on outgoing interfaces. Another benefit is that topology changes are recognized more quickly. By default, the PIM state refresh messages are sent every 60 seconds.
317:
Once the other routers which need to receive those group packets have subscribed, the RP will unsubscribe to that multicast group, unless it also needs to forward packets to another router or node. Additionally, the routers will use
428:
132:(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. See RFC 5015.
121:
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,
388:
Suppose a router has Pruned, and some time later a receiver requests the multicast stream with an IGMP message. The router then sends a Graft message. In effect, "hey, I need that multicast stream over here now".
303:
If the data rate is high, the RP can send source-specific Join/Prune messages back towards the source and the source's data packets will follow the resulting forwarding state and travel un-encapsulated to the
225:
routing which flooded packets across the network and then pruned off branches where there were no receivers, PIM-SM explicitly constructs a tree from each sender to the receivers in the multicast group.
285:
The outgoing interfaces point to the neighboring downstream routers that have sent Join/Prune messages toward the RP as well as the directly connected hosts which have requested membership to group G.
310:
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.
300:
When a data source first sends to a group, its
Designated Router (DR) unicasts Register messages to the Rendezvous Point (RP) with the source's data packets encapsulated within.
313:
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.
307:
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.
85:. PIM is not dependent on a specific unicast routing protocol; it can make use of any unicast routing protocol in use on the network. PIM does not build its own
580:
248:
A Designated Router (DR) sends periodic Join/Prune messages toward a group-specific
Rendezvous Point (RP) for each group for which it has active members.
251:
Note that one router will be automatically or statically designated as the rendezvous point (RP), and all routers must explicitly join through the RP.
610:
671:- Protocol Independent Multicast, previously a separate independently released module for, but now an official module of and supplied by, the
256:
Each router along the path toward the RP builds a wild card (any-source) state for the group and sends Join/Prune messages on toward the RP.
245:
The router then forwards data packets addressed to a multicast group G to only those interfaces on which explicit joins have been received.
644:
356:
This difference shows up in the initial behavior and mechanisms of the two protocols. Dense Mode uses a fairly simple approach to handle
403:
239:
167:(BSR). Groups are either sparse or dense mode; Interfaces can be either. General improvements to protocol flexibility and efficiency.
553:
54:
107:(RP) per group, and optionally creates shortest-path trees per source. PIM-SM generally scales fairly well for wide-area usage.
369:
interest. Upon receiving a Prune message, the router will modify its state so that it will not forward those packets out that
342:
194:
370:
688:
46:
234:
A router receives explicit Join/Prune messages from those neighboring routers that have downstream group members.
361:
535:
322:
to ensure that there are no loops for packet forwarding among routers that wish to receive multicast packets.
654:
259:
The term route entry is used to refer to the state maintained in a router to represent the distribution tree.
381:
319:
90:
217:) will subscribe to the multicast session. Unlike earlier dense-mode multicast routing protocols such as
617:
338:
494:
183:
209:
because it is not dependent on any particular unicast routing protocol for topology discovery, and
365:
350:
214:
672:
398:
190:
66:
50:
238:
In order to join a multicast group, G, a host conveys its membership information through the
649:
484:
453:
82:
78:
290:
This state creates a shared, RP-centered, distribution tree that reaches all group members.
222:
114:
30:
480:
Protocol
Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)
213:
because it is suitable for groups where a very low percentage of the nodes (and their
682:
635:
Protocol
Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification (Revised)
586:
86:
660:
Protocol
Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification rfc2362
357:
202:
58:
554:"Supplement on guidelines on deployment of IP multicast for IPTV content delivery"
522:
518:
514:
510:
506:
497:
478:
151:
17:
373:. If every interface on a router is pruned, the router will also be pruned.
634:
457:
334:
198:
118:
70:
187:
659:
639:
655:
pimd is a lightweight stand-alone PIM-SM v2 multicast routing daemon.
489:
539:
345:
to the multicast subscribers. It is an alternative to sparse mode.
353:
must receive and forward these packets (groups of a high density).
282:
The wild card route entry's incoming interface points toward the RP
103:(PIM-SM) explicitly builds unidirectional shared trees rooted at a
665:
557:
434:
218:
123:
81:
mechanism, but instead uses routing information supplied by other
147:
143:
477:
B. Fenner; M. Handley; H. Holbrook; I. Kouvelas (August 2006).
117:
routing. It implicitly builds shortest-path trees by flooding
62:
274:
the list of outgoing interfaces to which packets are sent
536:"Frequently Asked Questions (FAQ) File for Multicasting"
271:
the incoming interface from which packets are accepted
423:
421:
419:
126:used dense-mode multicast routing. See RFC 3973.
640:An Overview of Source-Specific Multicast (SSM)
146:systems for routing multicast streams between
8:
176:Protocol Independent Multicast - Sparse-Mode
34:Example of a multicast network architecture
645:Netcraftmen Explanation of PIM Sparse Mode
575:
573:
262:A route entry may include such fields as:
488:
89:. PIM uses the unicast routing table for
430:IP Multicast Routing Configuration Guide
29:
415:
77:because PIM does not include its own
7:
454:"PIM-SM Multicast Routing Protocol"
404:Multicast Source Discovery Protocol
380:Additionally, the routers will use
201:groups that may span wide-area and
240:Internet Group Management Protocol
25:
650:PIM-SM Multicast Routing Protocol
205:internets. The protocol is named
96:There are four variants of PIM:
582:Configuring IP Multicast Routing
538:. Multicast Tech. Archived from
360:routing. The source initially
39:Protocol-Independent Multicast
1:
667:qpimd – PIM Daemon for Quagga
136:PIM Source-Specific Multicast
61:distribution of data over a
142:PIM-SM is commonly used in
53:(IP) networks that provide
47:multicast routing protocols
705:
525:.
27:Multicast routing protocol
483:. Network Working Group.
609:Gorry Fairhurst (2006).
154:or local area networks.
382:reverse-path forwarding
337:can use to construct a
320:reverse-path forwarding
277:timers, flag bits, etc.
91:reverse-path forwarding
513:. Updated by RFC
505:Obsoleted by RFC
35:
509:. Obsoletes RFC
33:
673:Quagga Routing Suite
331:Dense mode multicast
207:protocol-independent
75:protocol-independent
79:topology discovery
36:
689:Routing protocols
399:Multicast address
333:is one mode that
295:Multicast sources
268:the group address
230:Multicast clients
191:Internet Protocol
130:Bidirectional PIM
83:routing protocols
51:Internet Protocol
45:) is a family of
16:(Redirected from
696:
670:
631:
629:
628:
622:
616:. Archived from
615:
596:
595:
594:
593:
577:
568:
567:
565:
564:
550:
544:
543:
532:
526:
501:
492:
490:10.17487/RFC4601
474:
468:
467:
465:
464:
450:
444:
443:
442:
441:
425:
186:for efficiently
165:Bootstrap Router
105:rendezvous point
73:. It is termed
21:
704:
703:
699:
698:
697:
695:
694:
693:
679:
678:
664:
626:
624:
620:
613:
608:
605:
600:
599:
591:
589:
579:
578:
571:
562:
560:
552:
551:
547:
534:
533:
529:
476:
475:
471:
462:
460:
452:
451:
447:
439:
437:
427:
426:
417:
412:
395:
328:
297:
232:
223:dense multicast
173:
160:
115:dense multicast
101:PIM Sparse Mode
28:
23:
22:
15:
12:
11:
5:
702:
700:
692:
691:
681:
680:
677:
676:
662:
657:
652:
647:
642:
637:
632:
604:
603:External links
601:
598:
597:
569:
545:
542:on 2011-06-14.
527:
469:
445:
414:
413:
411:
408:
407:
406:
401:
394:
391:
327:
324:
315:
314:
311:
308:
305:
301:
296:
293:
292:
291:
288:
287:
286:
283:
280:
279:
278:
275:
272:
269:
266:
265:source address
260:
254:
253:
252:
246:
243:
231:
228:
172:
169:
159:
156:
140:
139:
133:
127:
113:(PIM-DM) uses
111:PIM Dense Mode
108:
87:routing tables
26:
24:
18:PIM Dense Mode
14:
13:
10:
9:
6:
4:
3:
2:
701:
690:
687:
686:
684:
674:
669:
668:
663:
661:
658:
656:
653:
651:
648:
646:
643:
641:
638:
636:
633:
623:on 2011-12-28
619:
612:
611:"PIM Routing"
607:
606:
602:
588:
587:Cisco Systems
584:
583:
576:
574:
570:
559:
555:
549:
546:
541:
537:
531:
528:
524:
520:
516:
512:
508:
504:
499:
496:
491:
486:
482:
481:
473:
470:
459:
455:
449:
446:
436:
432:
431:
424:
422:
420:
416:
409:
405:
402:
400:
397:
396:
392:
390:
386:
383:
378:
374:
372:
367:
363:
359:
354:
352:
346:
344:
340:
336:
332:
325:
323:
321:
312:
309:
306:
302:
299:
298:
294:
289:
284:
281:
276:
273:
270:
267:
264:
263:
261:
258:
257:
255:
250:
249:
247:
244:
241:
237:
236:
235:
229:
227:
224:
220:
216:
212:
208:
204:
200:
196:
192:
189:
185:
181:
177:
170:
168:
166:
157:
155:
153:
149:
145:
137:
134:
131:
128:
125:
120:
116:
112:
109:
106:
102:
99:
98:
97:
94:
92:
88:
84:
80:
76:
72:
68:
64:
60:
56:
52:
48:
44:
40:
32:
19:
666:
625:. Retrieved
618:the original
590:, retrieved
581:
561:. Retrieved
548:
540:the original
530:
502:
479:
472:
461:. Retrieved
448:
438:, retrieved
429:
387:
379:
375:
358:IP multicast
355:
347:
341:for sending
330:
329:
316:
233:
210:
206:
203:inter-domain
179:
175:
174:
164:
161:
141:
135:
129:
110:
104:
100:
95:
74:
59:many-to-many
42:
38:
37:
211:sparse-mode
171:Sparse mode
55:one-to-many
627:2011-12-06
592:2013-12-06
563:2014-03-23
463:2014-03-26
440:2017-05-27
410:References
362:broadcasts
326:Dense mode
503:Obsolete.
458:Microsoft
371:interface
364:to every
335:multicast
199:multicast
119:multicast
683:Category
393:See also
184:protocol
158:Versions
71:Internet
351:routers
343:packets
242:(IGMP).
215:routers
195:packets
188:routing
182:) is a
152:Subnets
69:or the
366:router
180:PIM-SM
621:(PDF)
614:(PDF)
558:ITU-T
435:Cisco
219:DVMRP
193:(IP)
148:VLANs
124:DVMRP
523:6226
521:and
519:5796
515:5059
511:2362
507:7761
498:4601
339:tree
221:and
144:IPTV
57:and
49:for
495:RFC
485:doi
304:RP.
197:to
67:WAN
63:LAN
43:PIM
685::
585:,
572:^
556:.
517:,
493:.
456:.
433:,
418:^
150:,
93:.
65:,
675:.
630:.
566:.
500:.
487::
466:.
178:(
41:(
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
