350-801 · Question #105
Refer to the exhibit. What is a possible cause of the PRI issue?
The correct answer is D. The framing is configured incorrectly. Incorrect framing configuration is a common cause for PRI issues, as it prevents the physical layer from establishing a stable connection and synchronizing with the service provider's equipment.
Question
Refer to the exhibit. What is a possible cause of the PRI issue?
Exhibit
Options
- AThe cable is unplugged.
- BThe controller shut down.
- CThe clock source is incorrect.
- DThe framing is configured incorrectly.
How the community answered
(41 responses)- A2% (1)
- B7% (3)
- C2% (1)
- D88% (36)
Why each option
Incorrect framing configuration is a common cause for PRI issues, as it prevents the physical layer from establishing a stable connection and synchronizing with the service provider's equipment.
If the cable were unplugged, the controller status would likely show 'down' and potentially 'alarm received' or 'no carrier,' indicating a direct physical layer issue rather than a configuration mismatch.
A 'shut down' controller would explicitly show an administrative shutdown state in the controller status; incorrect framing implies the controller is enabled but cannot synchronize.
An incorrect clock source can cause slips and errors, potentially leading to Layer 2 instability, but incorrect framing is a more fundamental Layer 1 mismatch that prevents any stable operation from the start.
If the framing (e.g., ESF, SF) or line coding (e.g., B8ZS, AMI) configured on the router's PRI interface does not match the service provider's settings, the physical layer (Layer 1) cannot establish properly. This mismatch prevents the ISDN signaling (Layer 2) from coming up, leading to PRI operational failures.
Concept tested: PRI Layer 1 troubleshooting (framing)
Source: https://www.cisco.com/c/en/us/support/docs/voice-unified-communications/h-323/18412-pri-troubleshoot.html
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