Optical TAPs

How to Select the Proper Split Ratio on 10G Fiber-Optic Links?

Please see the FAQ document that provides some background facts and guidelines that will help you select the proper split ratio for your 10G fiber-optic links.

I just connected my end nodes (typically a switch and a router) to an optical tap. The end nodes are successfully communicating but when I make a logical connection, map or pass-all in the GigaVUE,no frames are coming out of the tool ports. Why is that happening?

Answer: The most common reason for this symptom is that the transmit (Tx) and receive (Rx) fibers are reversed on both the switch and router. If this is the case the show port-params command will indicate extremely low or no light coming into the interface. The show-port-stats command will indicate IfInErrors are occurring also. You should execute those commands to verify this is the case.
To understand why this is happening look at the diagrams below.

Diagram A.

In Diagram A, the switch and router Tx and Rx fibers are connected correctly. The end nodes both see light passed through successfully to each other. The light is travelling in the same direction as the splitter, so 30% of the light is successfully split off and sent into the GigaVUE.

Diagram B.

In Diagram B, the switch and router Tx and RX fibers are connected incorrectly. The end nodes both see light passed through successfully to each other. The light is travelling in the opposite direction as the splitter, so very little or none of the light is successfully split off and sent into the GigaVUE.
The solution is to reverse the physical connections of the Tx and Rx leads on both the end nodes.

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