A media enterprise streams studio video to 200 receivers across a PIM sparse-mode campus where most groups have few active sources and RP load is rising, and engineers debate shared-tree efficiency versus optimal paths. Which source-tree versus shared-tree and PIM sparse-mode operation best balances RP load and path optimality?
Select an answer to reveal the explanation.
Short Explanation
Meet at the lobby, then take the shortcut once you know the way. Shared trees find sources through the RP, then SPT cuts the optimal trail, easing rendezvous strain. Camping in the lobby forever just congests the meeting spot.
Full Explanation
PIM sparse mode receivers join a shared (,G) tree toward the rendezvous point for scalable discovery, then the last-hop router triggers (S,G) shortest-path switchover toward the source for optimal forwarding, which offloads sustained high-rate traffic from the RP while preserving efficient discovery for sparse groups. Permanent shared trees for high-rate flows fail by concept because all traffic hairpins through the RP, concentrating load, adding latency, and creating a bottleneck and failure domain. Source trees without any RP fail by concept because sparse mode requires the RP mapping and shared-tree discovery to learn active sources before building (S,G), so eliminating it breaks receiver discovery. Flooding like dense mode fails by concept because push-and-prune everywhere wastes bandwidth and state across 200 receivers when few need each group, opposite to sparse efficiency. For the exam, remember shared means (,G) via RP and source means (S,G) via SPT switchover, and in practice verify SPT thresholds and RP placement to balance join latency and load.