Abstract: In a partially interconnected topological network having at least six topological nodes, a topological node being a single physical node or a group of interconnected physical nodes or part of a physical node or a group of interconnected physical nodes and parts of physical nodes, each topological node having at least three point-to-point topological links connecting it to some, but not all, of the plurality of topological nodes, there is at least one choice of routing between any two topological nodes, where the choice of routing is either two point-to-point topological links connected in series at another of the topological nodes or a direct point-to-point topological link between the two topological nodes.

Abstract: A partially interconnected network has a plurality of topological nodes, each of the topological nodes having at least three direct point-to-point topological links connected to other topological nodes. Each of a proportion of the plurality of topological nodes is connected to one of a group of point-of-presence (PoP) units. The group of PoP units is arranged to provide access to a selected service or services, one or more of each of the at least three direct point-to-point topological links from each topological node not being connected to one of a group of PoP units connecting to one or more than one of the plurality of topological nodes being connected to one of the group of PoP units. There is at least one choice of routing between any two topological nodes, the choice of routing being either via two topological links connected in series at another topological node or a direct point-to-point topological link between the two topological nodes.

Abstract: A network has a plurality of nodes, wherein at least one of the plurality of nodes includes a switch arranged to carry out a Simple Transit Core Function and three or more of the plurality of nodes include a Single Link Interface which Single Link Interface has associated Output Attributes and/or Input Cognizant Attributes. Each Simple Transit Core Function at one node is not logically connected to another Simple Transit Core Function at another node. Each Simple Transit Core Function at one node is logically connected to at least three Single Link Interfaces at other nodes. The nodes including Single Link Interfaces which are connected to one instance of a node arranged to carry out a Simple Transit Core Function are controlled by respective Intercommunicating Connection Acceptance Control Processes according to the respective Output Attributes and/or Input Cognizant Attributes.

Abstract: A partially interconnected network comprises a plurality of allocated nodes, each allocated to one of a number of areas, a plurality of star nodes, and point-to-point interconnections between the allocated nodes and the star nodes. The number of areas with allocated nodes interconnected to an individual star node forms the number of routes from an individual star node, each of a proportion of the plurality of star nodes having connected thereat one of a group of point of presence (PoP) units. The group of PoP units is arranged to provide access to a selected service or selected services. The allocated nodes of a first of the areas are interconnected to a set comprising some, but not all, of the star nodes. Further of the areas are similarly interconnected to further sets each comprising star nodes.

Abstract: A communications switch comprising a plurality of numerically identified input traffic ports, a plurality of numerically identified output traffic ports, at least one significant label extractor and at least one numerical processor, the communications switch being arranged whereby each message entering the communication switch by a numerically identified input traffic port contains a header, which header contains a label stack, which label stack includes at least one valid label, of which one valid label is a significant label. The numerical value of the significant label contained within the header of a particular message which entered the communications switch via a particular numerically identified input traffic port is extracted by the at least one significant label extractor and is supplied to one of the at least one numerical processors.

Abstract: A partially interconnected network has a plurality of Allocated Nodes, each allocated to one of a number of AREAs, and further has a plurality of Star Nodes (STARs), and also has point-to-point interconnections between the Allocated Nodes and the STARs. The number of AREAs with Allocated Nodes connected to an individual STAR forms the number of ROUTEs from an individual STAR. The Allocated Nodes of a first of the AREAs are connected to a set comprising some, but not all, of the STARs. Further of the AREAs are similarly interconnected to further sets each comprising STARs. There is at least one connection choice between any two Allocated Nodes in different AREAs and where a connection route is two point-to-point interconnections connected in series by a STAR.

Abstract: A network has a plurality of nodes, wherein at least one of the plurality of nodes includes a switch arranged to carry out a Simple Transit Core Function and three or more of the plurality of nodes include a Single Link Interface which Single Link Interface has associated Output Attributes and/or Input Cognizant Attributes. Each Simple Transit Core Function at one node is not logically connected to another Simple Transit Core Function at another node. Each Simple Transit Core Function at one node is logically connected to at least three Single Link Interfaces at other nodes. The nodes including Single Link Interfaces which are connected to one instance of a node arranged to carry out a Simple Transit Core Function are controlled by respective Intercommunicating Connection Acceptance Control Processes according to the respective Output Attributes and/or Input Cognizant Attributes.

Abstract: A communications switch comprising a plurality of numerically identified input traffic ports, a plurality of numerically identified output traffic ports, at least one significant label extractor and at least one numerical processor, the communications switch being arranged whereby each message entering the communication switch by a numerically identified input traffic port contains a header, which header contains a label stack, which label stack includes at least one valid label, of which one valid label is a significant label. The numerical value of the significant label contained within the header of a particular message which entered the communications switch via a particular numerically identified input traffic port is extracted by the at least one significant label extractor and is supplied to one of the at least one numerical processors.

Abstract: A partially interconnected network comprises a plurality of allocated nodes, each allocated to one of a number of areas, a plurality of star nodes, and point-to-point interconnections between the allocated nodes and the star nodes. The number of areas with allocated nodes interconnected to an individual star node forms the number of routes from an individual star node, each of a proportion of the plurality of star nodes having connected thereat one of a group of point of presence (PoP) units. The group of PoP units is arranged to provide access to a selected service or selected services. The allocated nodes of a first of the areas are interconnected to a set comprising some, but not all, of the star nodes. Further of the areas are similarly interconnected to further sets each comprising star nodes.

Abstract: A partially interconnected network has a plurality of topological nodes, each of the topological nodes having at least three direct point-to-point topological links connected to other topological nodes. Each of a proportion of the plurality of topological nodes is connected to one of a group of point-of-presence (PoP) units. The group of PoP units is arranged to provide access to a selected service or services, one or more of each of the at least three direct point-to-point topological links from each topological node not being connected to one of a group of PoP units connecting to one or more than one of the plurality of topological nodes being connected to one of the group of PoP units. There is at least one choice of routing between any two topological nodes, the choice of routing being either via two topological links connected in series at another topological node or a direct point-to-point topological link between the two topological nodes.

Abstract: In a partially interconnected topological network having at least six Topological Nodes, a Topological Node being a single Physical Node or a group of interconnected Physical Nodes or part of a Physical Node or a group of interconnected Physical Nodes and parts of Physical Nodes, each Topological Node having at least three point-to-point Topological Links connecting it to some but not all of the plurality of Topological Nodes and there being at least one Choice of routing between any two Topological Nodes, where a Choice of routing is either two point-to-point Topological Links connected in series at another of the Topological Nodes or a direct point-to-point Topological Link between the two Topological Nodes.

Abstract: An Asynchronous Transfer Mode (ATM) multiplexed data stream is terminated at a functional unit. Virtual channel data are being carried in cells in the data stream. A depacketizer has a plurality of cell buffers, each buffer storing the payload data contained in a single cell. The buffers are being loaded in sequence in accordance with a message sequence number carried by each cell and emptied in accordance with a depacketizer algorithm to form a non-continuous data stream. A fill-in cell format generator, on the failure of a valid cell to arrive, causes the replacement of the missing cell by a fill-in cell in the non-continuous data stream. A time-out function generator is started after each cell has been depacketized and sometimes after fill-in replacement cells have been generated.

Abstract: A depacketizer is used in terminating an ATM multiplexed data stream at a functional unit, virtual channel data being carried in cells in the data stream. The depacketizer has a plurality of cell buffers each storing the data contained in a single cell and being loaded in the sequence of a message sequence number carried by each cell and emptied in accordance with a depacketizer algorithm to form a data stream. A fill-in cell format generator causes, on the failure of a valid cell to arrive, the replacement of the missing cell by a fill-in cell in the data stream. A time-out function generator is started after each cell has been depacketized and sometimes after fill-in replacement cells have been generated. A cell frame aligner has the depacketizer with a frame alignment signal detector which detects a frame alignment signal in the non-continuous data stream and generates an associated frame start signal and a loss of frame alignment signal as appropriate.

Abstract: A telecommunications data transmission system can provide transmission of data blocks using a unidirectional broadband link and a duplex narrowband link between two subscribers, the narrowband link providing control and addressing information regarding the data blocks sent via the broadband link from the first to the second subscriber, the transmission on the broadband link possibly being sent using Motion Picture Expert Group 2 encoding.

Abstract: The flexibility of a telecommunications switch fabric can be improved by making the fabric multipurpose. Where a switch fabric has two or more switches of different granularities, they may be connected by a terminating device in which the higher granularity circuits from the first switch are terminated and demultiplexed into the lower granularity circuits for the second switch, in addition to the lower granularity circuits from the second switch being multiplexed together to form higher granularity circuits for the first switch.

Abstract: The fitting of boundary buffers on the exit from a telecommunications network can greatly reduce the relative wander. Adaptive boundary buffers have a phase adjusting circuit, for determining the phase error between a recovered line clock and a recovered return clock from receiving equipment of a telecommunications system, the phase of the recovered return clock being advanced or retarded by the value of the phase error and the phase of the recovered line clock being retarded or advanced respectively by less than the value of the phase error, so as to produce a phase adjusted Output Line Clock.

Abstract: A telecommunications transmission system carries multiple tributary data streams with SDH compatible multiplexing and demultiplexing arrangements that include a tributary justification algorithm utilizing both byte and bit justification means as well as a double-ended payload protocol. The byte justification means employs an offset clock with a nominal constant frequency offset from the transmission system clock so that the offset clock can be used to force regular rate of byte justifications of constant sign. The bit justification means employs the difference between the tributary clock and the offset clock to determine the bit justifications necessary to multiplex the tributary data stream and the bit justifications are normally of complementary sign to the forced regular byte justifications except where the frequency of the offset clock lies between the frequency of the transmission clock.

Abstract: A pure ATM based multiplex is incapable, especially at low carrier rates, of satisfactorily carrying constant bit rate traffic or/human communication traffic. A multiplex format having a plurality of constant bit rate timeslots in which a timeslot is not in use for constant bit rate traffic can have that timeslot used for message based traffic to provide a composite constant bit rate/message based data stream.

Abstract: A telecommunication switch protection arrangement has information sent in the form of an information frame through a switch. The information in the frame is reorganized in the switch between input and output and checked for parity by using a V4 byte in the frame before being sent from the switch.

Abstract: A telecommunication network and switching system where digital circuits are supplied to customer terminals for dial-up services and where automatic testing of the access connections to the customer premises is performed while calls are not in progress. A loop test unit is provided at the customer's premises near to the customer digital line terminals able to detect a test sequence sent from an exchange when a call is not in progress, the test sequence being recognized by the loop test unit and a test sequence being returned to the exchange to enable the error performance of the link in both directions to be tested.