Abstract: A test system for diagnosing twisted pair wiring includes a system processor in communication with a subscriber line interface module, which includes a codec and a SLIC (Subscriber Line Interface Circuit). The SLIC transmits a waveform having a frequency used for voice or baseband modem transmissions onto the twisted pair wiring. The system processor transmits a digital PCM (Pulse Code Modulation) stream to the codec, and the codec converts the digital PCM stream into the waveform transmitted onto the twisted pair wiring. In response to the transmitted waveform, the SLIC senses current on the twisted pair wiring. The codec generates an output waveform corresponding to the sensed current. The system processor receives the output waveform from the codec as a digital PCM stream, synchronizes the transmitted waveform and the output waveform at a single sample, and determines electrical properties of the twisted pair wiring from the output waveform.

Abstract: A system and method for correlating events between protocol layers of a protocol stack of a network device includes detecting, at a first protocol layer, an occurrence of a first event associated with one or more data units received by the network device over physical media. A first times-tamp is associated with the first event. At a second protocol layer, an occurrence of a second event associated with the one or more data units is detected The second protocol layer is at a higher protocol layer of a protocol stack than the first protocol layer. A second timestamp is associated with the second event. A determination is made whether there is a correlation between the first and second events based on the first and second timestamps. Causation of the second event at the second protocol layer may be attributable to the first event at the first protocol layer.

Abstract: A test system for diagnosing twisted pair wiring includes a system processor in communication with a subscriber line interface module, which includes a codec and a SLIC (Subscriber Line Interface Circuit). The SLIC transmits a waveform having a frequency used for voice or baseband modem transmissions onto the twisted pair wiring. The system processor transmits a digital PCM (Pulse Code Modulation) stream to the codec, and the codec converts the digital PCM stream into the waveform transmitted onto the twisted pair wiring. In response to the transmitted waveform, the SLIC senses current on the twisted pair wiring. The codec generates an output waveform corresponding to the sensed current. The system processor receives the output waveform from the codec as a digital PCM stream, synchronizes the transmitted waveform and the output waveform at a single sample, and determines electrical properties of the twisted pair wiring from the output waveform.