Multiplex communications – Wide area network – Packet switching
Patent
1990-10-31
1993-05-11
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
370 60, 370 941, 340826, H04Q 1104, H04L 1256
Patent
active
052107426
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a communication process wherein use is made of a communication system with a switching network to establish connections between outside nodes via inside nodes which are each able to interconnect communication paths, wherein at least one of said outside nodes is able to transmit a forward signal in the direction of another outside node via at least one inside node, wherein said one inside node upon the receipt of said forward signal on a communication path either transmits said forward signal on a communication path in the direction of said other outside node or transmits a backward signal on a communication path in the direction of said one outside node, and wherein each node receiving said backward signal releases the communication path connecting it to the node having transmitted the backward signal.
BACKGROUND ART
Such a communication process, and more particularly a packet communication process, is already known in the art, e.g. from Belgian patent no. 905982. Therein the forward signal transmitted by the one outside node is a path setup packet which is used to establish a point-to-point path to the other outside node. Upon the receipt of the path setup packet by an inside node on an input communication path, this node selects a single output communication path in a wanted direction and depending on this selection being successful or not, transmits the packet further or converts it to a backward or so called blocked packet respectively. The blocked packet is transmitted to a preceding node and upon receipt of this packet, this node breaks down its output communication path constituting the above input communication path of the following node.
Because according to this known process a point-to-point path is concerned, the last mentioned input communication path is released if no corresponding output communication path is found in the wanted direction. If the same criterion would be used for a point-to-multipoint path where the input communication path is connected to a plurality of output communication paths in a plurality of directions, the release of this input communication path subsequent to the receipt of a blocked packet would provoke the erroneous release of all the paths. On the other hand, if to avoid such a situation one would use the blocked packet only to inform the outside node having generated the path setup packet that the path setup has been unsuccessful and not as an indication to a node that it has to break down a communication path, the latter would remain in the network as a partly established connection and the last mentioned outside node would not be aware of this fact if, for one or another reason, the blocked packet would get lost.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a communication process of the above type, but which prevents partly established paths from remaining in the network and is applicable to both point-to-point and point-to-multipoint paths.
According to the invention this object is achieved due to the fact that said one outside node is able to transmit a path release explorer signal, constituting said forward signal, in the direction of one or more other outside nodes on previously established paths and that each node upon the receipt of said explorer signal on a communication path checks if there are communication paths connected therewith and only in the absence of such paths transmits a path release signal, constituting said backward signal, in the direction of said one outside node.
In this way a partly established connection is able to be released by the path release signal independently of this connection being a point-to-point or a point-to-multipoint one, but only the partly established connections which do not form part of fully established connections are released.
According to the above known communication process at least one of said outside nodes is able to transmit a path setup signal in the direction of another outside node via at least one inside node, and
REFERENCES:
patent: 4486877 (1984-12-01), Turner
patent: 4561090 (1985-12-01), Turner
patent: 4692917 (1987-09-01), Fujioka
patent: 4817085 (1989-03-01), DePrycker
patent: 4965788 (1990-10-01), Newman
patent: 5020052 (1991-05-01), DePrycker et al.
M. De Prycker and J. Bauwens, "A Switching Exchange for an Asynchronous Time Division based Network," ICC 87, vol. 2/3, Jun. 7-10, 1987, IEEE, pp. 774-781.
Barri Peter I. A.
Beyne Luc O.
ALCATEL N.V.
Hsu Alpus H.
Olms Douglas W.
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