Question 490
An access switch reports valid IGMP membership for a pay-TV channel. Observed: The upstream PE never adds the receiver interface to its forwarding state. What evidence would validate recovery from this precise failure mode?
Explanation
Correct Answer
The intended result is The PE maps the local membership into forwarding toward the receiver. It specifically verifies recovery from igmp membership reporting or the igmp-to-pim boundary is misconfigured, which produced the original symptom: The upstream PE never adds the receiver interface to its forwarding state. It is stronger evidence than a generic interface-up indicator.
Incorrect Answers
This result is useful in another case with evidence One receiver never sees the stream although the other is healthy. It does not test recovery from the upstream pe never adds the receiver interface to its forwarding state. Check instead whether the PE maps the local membership into forwarding toward the receiver.
That observation would verify a separate fault involving the incoming interface differs from the preferred unicast reverse path to the source. Its symptom is PIM RPF discards increase when routing chooses the other uplink. For this case the actual issue is igmp membership reporting or the igmp-to-pim boundary is misconfigured, and the relevant success signal is The PE maps the local membership into forwarding toward the receiver.
It confirms an unrelated service correction: RPF-specific policy chooses an unintended interface relative to actual source arrival. The present case reports The upstream PE never adds the receiver interface to its forwarding state. Its completion test is The PE maps the local membership into forwarding toward the receiver.