Multiplex communications – Wide area network – Packet switching
Patent
1988-09-02
1990-12-04
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
H04Q 1104
Patent
active
049759019
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a network for message switching, in a particularly fast manner, between a plurality of processing units. To each of the processing units there is connected a serial transmission channel.
In the following description the switching network will be illustrated with reference to a switched digital type telephone exchange. Each processing unit is encased in its respective module of the exchange and the messages are constituted by signal messages. However, the network may be advantageously used for switching messages between any type of processing unit complex.
BACKGROUND OF THE INVENTION
Modern digital type telephone exchanges, of the type suitable to switch vocal and/or data signals in the form of PCM signals (Pulse Code Modulation), are usually designed to include the presence of a plurality of input/output modules, to each of which a predetermined number of users and/or a predetermined number of trunk lines can be connected. Each of the modules includes a processing unit for analysing the signalling criteria associated to voice and/or data signals, and also to structure them in the form of messages which can be switched between the modules.
It is known, in modern digital switched exchanges, switching operations concerning vocal and/or digital signals are carried out by means of a connection network on the basis of indications contained in the signal messages.
The connection network includes switching modules which in turn also include a processing unit.
Switching operations of signal messages can be carried out by using predetermined channels of the connection network, or by means of a switching network that is separate from the connection network. However it must be kept in mind that use of the connection network for switching signal messages involves the introduction of time delays necessary for crossing the network which are fundamentally caused by the times required to carry out connection network pre-patterning operations. In some circumstances the crossing times, mentioned above, are not compatible with the times required for correct operation of the switched exchange.
The fact, must also be kept in mind, that realization of a signal message switching network that is separate from the connection network, makes it possible to avoid the above described inconveniency concerning the transit times of messages, but also involves overcoming certain technical problems such as the following:
(a) switching messages with a number of words (bytes) that differs from message to message;
(b) switching messages which are output from the single modules in a non cyclic manner and according to a rhythm (the number of messages in a time unit) which differs from module to module, thus avoiding the danger of losing messages;
(c) synchronize the output module and the destination module with each other;
(d) allow a generic message to be sent to a single destination module, as also to a group of modules or to all the modules;
(e) guarantee scanning of all modules in a predetermined time interval;
(f) carry out useful functions for diagnosis of the switched message network and of the organs linked up to it.
One purpose of the present invention is to realize a fast switching network of the signal messages, that is separated from the connection network, and has the aforementioned requisites.
Such a switching network has been described, for example, by Bovo et al in the article "UT 100/60--An electronic digitale family of exchanges for a large capacity Applications" Proceeding of ISS 1/84--Florence, Italy; Session 14 B, pages 5; page 5, left-hand) with particular reference to FIG. 5 et al.
FIG. 5 of the Bovo article shows a message distributor module block diagram where the message distributor network, connected to N external Module Processors, comprises (connected one another) N input interfaces R, multiplexing means driven by a control logic and N output interfaces R.
Therefore an object of the present invention is a network for switching messages between a plurality
REFERENCES:
patent: 4592045 (1986-05-01), Fundneider
patent: 4835766 (1989-05-01), Arutaki et al.
patent: 4839888 (1989-06-01), Baltz et al.
"UT100/60--An Electronic Digital Family of Exchanges for Large Capacity Applications".
Hsu Alpus H.
Italtel Societa Italiana
Olms Douglas W.
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