Forte Networks, Inc.

Fluke Corporation

John Fluke Mfg. Co., Inc.

Mark Copley

Charles H Whiteside

Gordon A Jensen

David G Fish

Chris L Odell

Thomas S Wisdom, Jr

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. The state character for each token ring station is determined using predetermined algorithms that are based on the presence/absence of stations in the token ring.

Token ring local area network testing apparatus providing station

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.

Token ring local area network testing apparatus inserted in an active 'T' c

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.

Token ring local area network testing apparatus for matching its speed

A token ring local area network (LAN) testing apparatus is provided. The apparatus is able to conduct a phase jitter measurement without disruption of normal token ring operation. The apparatus transmits a frame that includes phase jitter test data. This frame is transmitted into the token ring, together with a clock signal. After return of the frame with the phase jitter test data, a comparison is made between the recovered clock signal accompanying this frame and a reference clock signal. The result of this comparison provides a sample used in determining phase jitter. In making the measurement, an interpolation circuit is utilized to increase the resolution of the time difference between the recovered clock signal and the reference clock signal. A clamp circuit is used to ensure that each interpolation begins at the same reference voltage, as well as ensuring that the interpolation process is properly discontinued.

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Colorado Springs, CO, United States of America

Mark Copley