Star data network with logical ring function preferably using to

Details Star data network with logical ring function preferably using to Star data network with logical ring function preferably using to

1991-08-21

1994-05-31

Chin, Wellington

Multiplex communications

Wide area network

Packet switching

370 854, 370 943, H04L 1244

Patent

active

053175603

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The invention relates to a star data network with logical ring function preferably utilizing token access.


BACKGROUND ART

Star data networks with logical ring function utilizing token access have been well known for ten years. An exhaustive description of the concept and its realization with the aid of line concentrators was published in 1983 in IBM systems Journal vol 22, nos 1/2, by R. C. Dixon, N. C. Strole and J. D. Markow.
Embodiments known up to now of data network with logical ring function usually have the disadvantage of requiring new lines for achieving satisfactory function. This means that large earlier investments in terminal networks with coaxial cables cannot be utilized in such embodiments.


DISCLOSURE OF THE INVENTION

The invention relates to a star data network with token access realized in such a way that use can be made of earlier investments in terminal networks with coaxial cables.
In addition, the invention enables the utilization of simpler and less voluminous connector means than what is indicated in the specification ISO/DIS 8802/5 for data networks according to the above.
In accordance with the invention this is achieved by a conventional line concentrator, with a plurality of bypass switching means each arranged for its respective link to a node in the data network, having each of the mentioned bypass switching means provided with a preferably active signal processing means disposed such as to superimpose on one signal side an incoming and an outgoing signal on the same transmission line in said link, and on its other signal side to smooth the incoming signal's contribution to the outgoing signal, and in that said transmission line in said link is connected to said node via a preferably passive signal processing means with a function corresponding to the function of said preferably active signal processing means, said transmission line preferably comprising a coaxial cable installed in an earlier terminal network. In a preferred embodiment in accordance with the invention of the preferably active signal processing means, the latter includes an amplifying comparator with a reference input adapted for having supplied to it the incoming signal via a first attenuation circuit and with a signal input connected to said transmission line, which is adapted for being supplied with the incoming signal via a second attenuation circuit corresponding to the first attenuation circuit.


DESCRIPTION OF FIGURES

FIG. 1 is a block diagram of a star data network with logical ring function.
FIGS. 2 and 3 are circuit diagrams of preferred embodiments in accordance with the invention of an active and passive signal processing means, respectively.
FIG. 4 is a perspective view of a preferred embodiment of an adapter in accordance with the invention, in which the passive signal processing means according to FIG. 3 is included.


BEST MODE OF CARRYING OUT THE INVENTION

FIG. 1 is a block diagram illustrating a conventional star data network with logical ring function, including a first line concentrator 1 having, according to the example, three bypass switching means 2, 3, and 4 each arranged for a link 5, 6 and 7 to nodes 8, 9 and 10, and a second line concentrator 11 with bypass switching means 12, 13 and 14 each arranged for links 15, 16 and 17 to nodes 18, 19 and 20 in the data network. The two line concentrators are connected together by a link 23 and bypass switching means 21 and 22.
A more detailed description of the function of the data network in FIG. 1, utilizing token access is published in IBM Systems Journal vol 22, nos 1/2, 1983 by R. C. Dixon, N. C. Strole and J. D. Markov.
Embodiments known so far of data networks with logical ring function utilizing token access have the disadvantage of requiring new lines for achieving satisfactory function. The specification IEEE 802.5 / ISO/DIS 8802/5 has been prepared for ensuring the function.
In accordance with the invention, satisfactory function in the data network according to FIG. 1 and compatibility with the above mentio

REFERENCES:
patent: 4270214 (1981-05-01), Davis et al.
patent: 4384363 (1983-05-01), Lipcon
patent: 4481641 (1984-11-01), Gable et al.

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