Question 550
A video provider runs PIM dense mode on a shared transit interface. Observed: Traffic reaches links with no subscribers until prune state forms. What evidence would validate recovery from this precise failure mode?
Explanation
Correct Answer
The intended result is Unsubscribed transit links no longer carry unnecessary multicast traffic. It specifically verifies recovery from dense-mode initial flooding conflicts with the bandwidth-sensitive shared network, which produced the original symptom: Traffic reaches links with no subscribers until prune state forms. It is stronger evidence than a generic interface-up indicator.
Incorrect Answers
This result is useful in another case with evidence The link is in dense-mode flood-and-prune behavior rather than sparse-mode operation. It does not test recovery from traffic reaches links with no subscribers until prune state forms. Check instead whether unsubscribed transit links no longer carry unnecessary multicast traffic.
That observation would verify a separate fault involving rpf-specific policy chooses an unintended interface relative to actual source arrival. Its symptom is Multicast stream briefly loops and then disappears even though source route remains in RIB. For this case the actual issue is dense-mode initial flooding conflicts with the bandwidth-sensitive shared network, and the relevant success signal is Unsubscribed transit links no longer carry unnecessary multicast traffic.
It confirms an unrelated service correction: PIM sparse mode rightly prunes branches without subscribed receivers. The present case reports Traffic reaches links with no subscribers until prune state forms. Its completion test is Unsubscribed transit links no longer carry unnecessary multicast traffic.