What is a concept associated with PIM sparse mode (SM)?
What is a concept associated with PIM sparse mode (SM)?
In Protocol Independent Multicast Sparse Mode (PIM-SM), routers need to periodically send join messages to maintain the shortest path tree (SPT). This is crucial because PIM-SM is designed to efficiently manage multicast traffic in sparse environments by constructing a tree only when necessary, ensuring that multicast data is only sent to routers that have explicitly requested it. This contrasts with Dense Mode (DM), where data is flooded throughout the network unless pruned. Hence, periodic joins are essential in PIM-SM to keep the multicast routing state active by indicating continued interest in receiving the multicast traffic.
Correct Answer: B https://www.youtube.com/watch?v=PhzMcUcS6UA
https://www.arubanetworks.com/techdocs/AOS-CX/10.07/HTML/5200-7876/Content/Chp_pim-sm/how-pim-sm-wor-10.htm: In a PIM domain, each PIM interface on a router periodically multicasts PIM hello messages to all other PIM routers (identified by the address 224.0.0.13 for V4 and ff02::d for V6) on the local subnet. Through the exchanging of hello messages, all PIM routers on the subnet determine their PIM neighbors, maintain PIM neighboring relationship with other routers, and build and maintain shortest path trees (SPTs).
B is correct : From ACSP learning book Multicast Routing : "PIM-SM builds the multicast routing tree for a group in advance and then forwards multicast on that tree when a source begins to stream to that group. PIM-SM enabled routing interfaces must specifically indicate that they want to receive multicast traffic in a particular group by sending a JOIN for the three" A is incorrect because "pruning" is a PIM-DM concept C is incorrect because PIM-SM : From ACSP learning book Multicast Routing : "Because PIM-SM establishes efficient forwarding paths, it is well suited for a lower bandwidth environment, such as one built on WAN links. D is incorrect: : From ACSP learning book Multicast Routing : "The best way of comparing the two protocoles is PUSH (PIM-DM) versus PULL (PIM-SM)"