A network administrator installs a new 10Gbps LC duplex fiber patch cable between two core switches using matching SFP+ transceivers. After plugging in the cable, the link status LEDs on both switch interfaces remain completely dark. Testing with a visual fault locator (VFL) confirms light is passing through both fiber strands with no physical breaks. Which of the following is the most appropriate troubleshooting action to resolve this issue?
- Reverse the positions of the transmit (Tx) and receive (Rx) fiber strands on one end of the LC duplex connector.Answer
- BUse a copper Time-Domain Reflectometer (TDR) to locate signal attenuation points along the cable length.
- CRe-terminate both ends of the fiber patch cable using the T568B color-code wiring standard.
- DConnect a tone generator and inductive probe kit to trace light emissions along the optical cable.
Answer
Reverse the positions of the transmit (Tx) and receive (Rx) fiber strands on one end of the LC duplex connector.
Swapping the transmit (Tx) and receive (Rx) strands on one connector end resolves a fiber polarity inversion. Duplex fiber communications require a crossover layout (Tx to Rx). When connected straight-through (Tx-to-Tx / Rx-to-Rx), optical signals are directed into transmit lasers rather than receivers, preventing link establishment even when light continuity is verified.
Step-by-Step Solution
Key Concept
Fiber Optic Polarity and Duplex Connection Troubleshooting
Estimated Time:1m 30s