Adaptive interface apparatus and method for data terminal elements in a communication network transmitting and receiving ethernet over a shielded twisted pair cabling system

摘要

An adaptive interface and method of operation facilitate connection of a work station in a Local Area Network (LAN) using Shielded Twisted Pair (STP) cabling to an Ethernet 10/100BASE TX installation using Unshielded Twisted Pair (UTP). The work station is coupled through the adaptive interface to the STP cabling system emulating a given number of meters of UTP cabling. The interface adapter comprises at one end a RJ 45 connector adapted for connection to the STP cabling and at the other end a MIC_S token ring connector coupled to an Ethernet adapter through the STP cabling system. The adaptive interface includes programmatically controlled filters interconnecting the RJ 45 and MIC_S connectors. The filter comprises a series of 1 . . . N switchable lumped passive element units which can be sequentially connected into the STP cabling to emulate the amplitude attenuation and phase shift of a preselected length of UTP 5 cabling, typically in the range of 20 meters. In operation, the Physical Layer (PHY) in the communication system enters a start up sequence for the various circuits and cabling in the layer. During the start up sequence, the adaptive interface is bypassed. After an appropriate delay to allow PHY convergence or a bit error rate measurement, the PHY transmit/receive signals are examined for bit errors by a test unit. If there are no bit errors, no filter element is inserted in the STP cabling by the adaptive interface and the work station is coupled to the Ethernet installation. If there are bit errors, a first filter element is switched into the STP cabling by the adaptive interface. The bit error signals are re-examined. If there are no errors, the workstation is connected to the Ethernet installation. If bit errors continue to exist, the next element(s) of the filter is inserted into the STP cabling until the “Nth” filter element is reached. If bit errors continue to exist on the STP cabling after inserting the Nth filter in the STP cabling, a re-try test sequence is initiated by the adaptive interface and the start up sequence is repeated. If re-try is not initiated, a transmit error is displayed and the workstation/Ethernet installation cannot proceed without modification. A diagnostics menu is displayed and a set-up process determines with human intervention what system changes are needed for the workstation/Ethernet connection.