Method and apparatus for monitoring a dedicated communications medium in a switched data network

the bypass circuit as may be utilized in the probe 400 of FIG. 4 is now described with reference to FIG. 6. A probe 400 is shown (in dotted lines) coupled between a switch 220 and a network device 1 (i.e., data terminating equipment--DTE) via a transmit / receive pair of lines, e.g., conventional unshielded twisted pair wiring operating in full duplex. The transmit / receive pair is coupled from the probe to the switch at port 407 and the DTE at port 408 by way of, for example, standard RJ45 connectors. The output of the switch is transmitted out the transmit port (TX) 407a over the transmit line and passes through a high impedance passive tap 422 in the probe to the receive port (RX) 408a of the DTE (network device). The other line in the full duplex link is coupled between the transmit port (TX) 408b of the DTE and the receive port (RX) 407b of the switching hub 220. This line passes through a high impedance passive tap 424 in the probe. Within the probe, tap 424 is connected to ampl