Observer nTAPs : Observer nTAPs : FAQ : Are the analyzer ports “send only”?
Are the analyzer ports “send only”?
Yes, the analyzer ports are send only. The TAP is incapable of sending data from the Analyzer side of the TAP to the Link (or network) side of the TAP.
The “A,” “B,” or “AB” ports on the Analyzer side of the TAP must be capable of both transmitting and receiving data to negotiate a connection with the analyzer and they do this through the physical interface. The physical interface is responsible for negotiating a bi-directional connection with the analyzer and unidirectionally sending data from the TAP to the analyzer.
There is no physical connection between the receive port on the Analyzer side of the TAP and the TAP’s internal processor. Therefore, the TAP cannot transmit data from the analyzer back to the Link side of the TAP.
This image shows the data flow for the High Density Optical TAP. In it you can see a Y-cable is used to connect the TAP to the Analyzer. Notice that only the RX side of the LC connectors in the Analyzer have a physical cable. The TX side of the LC connectors in the Analyzer—even if there is a cable present—cannot send data to the TAP.
 
Figure 5: Send only
 
All TAPs that have an optical connection to the Analyzer use the Y-cable. This includes the pure optical TAPs, Copper-to-Optical Conversion, and Copper-to-Optical Aggregator. Instead of a Y-cable two single TX-to-RX connectors could be used. The TX side is inserted into the TAP and the RX into the Analyzer.
 
Figure 6: Y-cable for optical TAPs