Abstract: In a Telecommunications Infrastructure, an Access Network or Segment of an Access-Layer Infrastructure has a plurality of subscribers or extensions linked to one or more gateways having ports and providing access to/from higher network layers. The linking from the subscribers or extensions to the gateways is carried out by the statistical-multiplexing of ATM cells carried in time-slots formatted onto broadband bearers. A desired gateway is identified by a number carried in the Virtual-Path Identifier field of each ATM cell. The source is identified by a number carried in an additional address field external to the ATM cell but internal to the time-slot. The linking from the gateways to the subscribers or extensions is via a distribution switch. The desired subscriber is identified by the number carried in the additional address field and the source is identified by the number carried in the Virtual Path Identifier field of the cell.

Abstract: To increase the number of subscriber network ports which may be accessed on a Broadband Integrated Services Digital (B-ISDN) access network using Asynchronous Transfer Mode (ATM) technology where a Concentration Function is provided by statistical multiplexers, a Grooming Function by ATM switches and own-access-network connections is provided by combining "upstream" ports into the core network(s) and the "downstream" ports to subscribers into a common address group. Each subscriber port and each core network(s) access port are allocated a unique OSI Layer 2 address. The access network destination address being carried in the Virtual Path Identifier (VPI) field of each ATM cell formatted according to relevant CCITT recommendations for the User Network Interface (UNI) or the Network to Network Interface (NNI).

Abstract: In a telecommunications switching network which has a plurality of sub-networks, each sub-network having a plurality of User Network Ports, the Destination and Source addresses in a cell-header carrier by a cell switched by the network are each divided into a Port Address part and a Sub-Network Address part, the Source Sub-Network part being implicit while the cell remains in the Source Sub-Network and similarly the Destination Sub-Network part is implicit when the cell arrives in the Destination Sub-Network, the Source and the Destination Sub-Networks being linked via a Cross-connect switching device wherein the address formats are changed.

Abstract: An asynchronous time division multiplex switching arrangement comprises a serial to parallel converter arranged to receive input packets of data which include routing information, in serial form and convert the packets of data to parallel form. A random access memory is provided in which each packet of data is entered at an addressed location into the memory, and the address is entered in a respective first-in first-out output queue at the tail. The address at the head of the queue is accessed and the packet of data is read from the random access memory into a parallel to serial converter and the packet of data is serially delivered to the associated output.

Abstract: The asynchronous time division network transmits data by way of high rate bearers. The data is divided into fixed length packets. The network comprises a switching matrix having a number of input and output ports arranged in columns. Each data packet is routed from an input port to a defined output port via addressed switching nodes. Each node has a queueing means, and each queueing means of each output column is tested and priority is given to the first queueing means tested which holds more than one packet.

Abstract: The fault detection and bandwidth monitoring arrangement provides a counter in association with each virtual circuit crosspoint. The counters may be provided with a common or individual threshold value which when exceeded causes alarm signals to be generated. The counter arrangement is arranged to record the averaged imbalance of receive and transmit data at each switch port involved in the virtual circuit connection, and additionally is arranged to measure the difference between the net data flows of the corresponding incoming and outgoing ports. Therefore, it is possible to distinguish between the go/return traffic imbalance and an information loss situation in the switch.

Abstract: A data packet switching arrangement wherein data packets are switched into a transmission pathway according to their priority. Data packet priority is consequently determined in a ring and a priority token attributed thereto. A high priority token ensures its data packet is switched into the transmission pathway when next available. Lower priority tokens are held by respective packets until all data packet priorities have been determined and no higher priority tokens attributed, whereupon the respective data packet is switched into the transmission pathway when next determined.

Abstract: A conventional interface for 2-wire telephone lines to a digital switch includes line current feed resistors and a bridge circuit where the line impedance is compared with a compromise balance network. The accuracy of the balance determines the proportion of the signal received on the receive pair being retransmitted in the transmit direction. The ratio of these signals is known as the Trans-Hybrid loss and should be as high as possible for good quality speech.In practice the telephone line impedance increases with length as also does the DC resistance of the line and thus the line current, assuming a constant voltage source.It is proposed that the line current feed resistors be formed on a common substrate using well-established film deposition techniques and the balance resistor be formed on the same substrate using a material having a negative temperature coefficient.