Question 420
A metro PE carries internet and private VPN traffic over one 10G interface. Observed: VPN queue counters show no packets despite known VPN load. Which ongoing validation gate would best detect a recurrence of this problem?
Explanation
Correct Answer
A useful regression gate tests whether vPN packets increment the intended queue counters and receive the agreed service and alerts when vPN queue counters show no packets despite known VPN load. This directly checks the technical weakness: Classifier and forwarding-class mappings do not match the chosen VPN traffic selector. The gate is derived from the fictional incident and is not an independent Juniper engineer signoff.
Incorrect Answers
This gate monitors a different failure, business telemetry is discarded even when its contracted rate is not exceeded. It would not detect the current problem: VPN queue counters show no packets despite known VPN load. The appropriate check requires vPN packets increment the intended queue counters and receive the agreed service.
The proposed control is tied to the wred drop-profile threshold curve or attachment is incorrect, typically observed when tail drops occur abruptly rather than the expected early-drop progression. Here the target is classifier and forwarding-class mappings do not match the chosen vpn traffic selector; monitor vPN packets increment the intended queue counters and receive the agreed service.
It is valid for another service scenario but checks bgp keepalives are delayed under volumetric guest transit load. This case instead needs a gate for vpn queue counters show no packets despite known vpn load and evidence that vPN packets increment the intended queue counters and receive the agreed service.