Question 540
A provider configures a multicast group filter at access ingress. Observed: A valid service group never creates IGMP membership on the PE. Which ongoing validation gate would best detect a recurrence of this problem?
Explanation
Correct Answer
A useful regression gate tests whether intended groups appear in membership state while prohibited groups remain excluded and alerts when a valid service group never creates IGMP membership on the PE. This directly checks the technical weakness: The group filter mistakenly denies the contracted multicast address. 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 packets are dropped by reverse-path-forwarding checks. This case instead needs a gate for a valid service group never creates igmp membership on the pe and evidence that intended groups appear in membership state while prohibited groups remain excluded.
The proposed control is tied to spt threshold or pim source-tree behavior is not aligned to the service policy, typically observed when shared-tree traffic continues after the receiver requests shortest-path switchover. Here the target is the group filter mistakenly denies the contracted multicast address; monitor intended groups appear in membership state while prohibited groups remain excluded.
This gate monitors a different failure, two rp nodes disagree on active source registrations. It would not detect the current problem: A valid service group never creates IGMP membership on the PE. The appropriate check requires intended groups appear in membership state while prohibited groups remain excluded.