General Electric Company

Telefonaktiebolaget Lm Ericsson (Publ)

Gec Plessey Telecommunications Limited

Anthony Peter Lumb

Ian Broadhurst

Donald David Stewart

Stuart Barratt

Dennis Fisher

Jayant Patel

Howard Green

John A Niblock

A communications system comprising a target node and at least one source node arranged for communication of messages there between; in which the target node comprises means for processing at least some of the messages received from the at least one source node and means for detecting the processing load of the target node; in which the target node comprises means for notifying the at least one source node when a specific processing load level has been reached or exceeded; and in which each source node comprises means for reducing, responsive to the notification, the rate at which messages are sent to the target node.

Communications system and method for load management

The invention relates to a data communications network and a method of operation thereof. A data communications network () is described which includes a call server () for the purpose of signalling, and a routing server () for the purpose of routing to permit communication between users of the network. The call server () is operable to send a request to the routing server () for the purpose of obtaining the identity of another call server () to which it is required to communicate. The request is provided with a parameter which relates to the origin of the communication within the data network () to enable a desired routing of the communication through the network.

Routing based upon origin of a call

A data communications network comprises a plurality of terminals (30, 31, . . . 34) which are interconnected by a contra-rotative ring pair of lines (35, 36), so as to be able to send data to and receive data from all the other terminals in the network. Each terminal has a pair of stations (A, B), each linked to said pair. The network is characterized in that one station associated with any one terminal is arranged to be as distant as possible in a topological sense from its associated pair.

Data communication network

To ensure security of interrupt input signals to a computer system (30-3N) with minimum interruption of the running of programs in the system, two interrupt logic units (1) receive interrupt signals on leads (20-2x) from connected apparatus and store flags representing the interrupt signals in an interrupt store (2). Control logic (3) compares each input signal with presettable criteria to determine if such signal is an interrupt signal and, if so, causes the data to be transferred by way of a read register (5) to the connected computer system (30-3N). At the same time the control logic (3) of one of the units (1) designated as the active unit also causes an ouput on a lead (11) to the other unit (1) designated as the standby unit. If the standby unit determines that an immediate interrupt has occurred and does not receive a signal on the lead (11), its respective control logic (3) will cause the contents of its interrupt store (2) to be transferred to its respective read register (5) and will also cause an additional flag to be entered in the read register (5) indicating the failure of the active unit (1). Designation of the two units (1) as 'active' or 'standby' is periodically changed by action of the computer system (30-3N).

Apparatus for controlling the transfer of interrupt signals in data

A data processing system having a large number of data processors (1-4) grouped in `clusters` is used in the control of a telecommunications exchange. The arrangement is such that any one of the processors may pass data to any other of the processors, in its own cluster by way of a synchronous data bus (5), or on other clusters by way of an interface (18, 19) and an asynchronous data bus (22). The arrangement permits larger number of processors (1-4) to have access to storage without undue delay in access to stored data.

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Warwickshire, United Kingdom

Anthony Peter Lumb