Question 480
A PIM sparse-mode domain has two possible rendezvous points. Observed: One RP fails but receivers stay joined to a dead shared tree. Which ongoing validation gate would best detect a recurrence of this problem?
Explanation
Correct Answer
A useful regression gate tests whether failover retains multicast delivery without stale RP dependency and alerts when one RP fails but receivers stay joined to a dead shared tree. This directly checks the technical weakness: RP redundancy and discovery were not implemented for the ASM service. The gate is derived from the fictional incident and is not an independent Juniper engineer signoff.
Incorrect Answers
It is valid for another service scenario but checks igmpv3 receivers cannot express source include lists to the router. This case instead needs a gate for one rp fails but receivers stay joined to a dead shared tree and evidence that failover retains multicast delivery without stale RP dependency.
The proposed control is tied to the group join state does not propagate through the intended pim path, typically observed when edge receivers are active but the intermediate router has no outgoing interface list. Here the target is rp redundancy and discovery were not implemented for the asm service; monitor failover retains multicast delivery without stale RP dependency.
This gate monitors a different failure, shared-tree traffic continues after the receiver requests shortest-path switchover. It would not detect the current problem: One RP fails but receivers stay joined to a dead shared tree. The appropriate check requires failover retains multicast delivery without stale RP dependency.