Abstract: A token ring local area network (LAN) testing apparatus is provided. The apparatus monitors history or status of token ring stations. Such information is useful in isolating token ring faults that may occur during its operation. The apparatus includes current and past memory lists that contain status information for each token ring station. The current station memory list contains addresses of all token ring stations that are present during a current neighbor notification process. The last station memory list contains addresses of all token ring stations that were present in the token ring during the neighbor notification process that was previous to the current neighbor notification process. A neighbor notification process is a conventional part of the token ring media access control (MAC) protocol. Included with the addresses in these lists is a determined one of a number of state characters that is indicative of station status.

Abstract: A testing apparatus for token ring local area networks (LANs) which can insert into the token ring network without requiring a separate port on a media access unit (MAU). The testing apparatus of the present invention is connected between a regular network station and the MAU. The testing apparatus is insertable into the network through the MAU, and the regular network station is able to insert into the network through the testing apparatus. Once inserted, the regular network station and the testing apparatus act as separate stations in series on the LAN. Due to its central position in this configuration, the testing apparatus is able to test for possible faults that might be present in the network and/or in the station to which it is connected. In addition, since the testing apparatus does not require a separate port on the MAU, no active user on the network needs to be disconnected for any extended period of time.

Abstract: A token ring local area network (LAN) testing apparatus is provided. The apparatus includes hardware and software that enables it to determine whether the testing apparatus is able to send frames into the token ring at a correct ring speed. The apparatus includes a conventional network interface card (NIC). The NIC includes two selectable clock signals, with the frequencies of the two clock signals being different. When the NIC is used in transmitting frames into the token ring, one of the two clock signals is selected to accompany the frames. The testing apparatus monitors whether frames and/or tokens are obtained from the token ring using the selected clock signal. If not, the testing apparatus causes the other clock signal to be selected. A determination of proper ring speed is made before a beacon condition occurs that would disrupt normal operation of the token ring.

Abstract: A method and apparatus for inserting a computer network protocol analyzer into a Token Ring network. Commercial integrated circuits are used to initiate a standard protocol test and synchronization sequence and to actuate an insertion relay in a network coupling unit. After actuation of the insertion relay, incoming network data is switched onto outgoing network data lines, bypassing the commercial protocol circuitry. As a result, the analyzer can be inserted into a Token Ring even when there are network problems which would prohibit insertion under normal protocol.

Abstract: Disclosed is a system that monitors the signal strength of each transmission by a node on a LAN cable of a local area network and determines the location of the node sending the signal. This system has a monitor at each end of the LAN cable, with one of the monitors typically being located in a computer node attached to the cable. When an information frame is sent on the cable, each of the monitors records the signal strength of the frame preamble and the source address contained within the frame. The distance to the node from a first end of the cable, expressed as a percentage of the length of the cable, is the ratio of the signal strength at the second end of the cable to the sum of the signal strengths.

Abstract: A system and method for detecting an improperly terminated network for networks using a collision detection access scheme. Embodiments of the present invention also contemplate a system and method for detecting a short circuit in a network. For detecting both an improperly terminated network and a short circuit in a network, the present invention relies on the detection of certain changes in the voltage of the network.