Abstract: There is provided a method of processing requests for target node identification data received from a first node of a data network at a second node of the data network, said first node processing user requests, said method comprising the following steps: a) storing, in a data store accessible by said second node, target node identification data for a set of a plurality of target nodes, each target node of said set being interchangeably useable by said first node to service a user request: b) receiving, at said second node, a plurality of similar requests from the first node, each one of said similar requests relating to said set of target nodes; c) in response to a first said similar request, selecting a first selection of one or more target nodes of said set and transmitting data identifying said first selection to said first node; d) in response to a second said similar request, selecting a second selection of one or more target nodes of said set and transmitting data identifying said second selection to sa

Abstract: A communications system having a line terminal(1), a plurality of customer terminals (2), and a passive optical network for supporting traffic between the line terminal and the customer terminals. The line terminal(I) has a terminal unit (BTS(n)) for relatively narrow bandwidth traffic, and a second terminal unit (BTS(1) to BTS(n-1)) for relatively wider bandwidth traffic. A time domain multiplexer (14) is arranged to multiplex the traffic from the first and second terminal unit for downstream transmission over the network (18). Each customer terminal (2) has a first service unit for relatively narrow bandwidth traffic and a second service unit for relatively wider bandwidth traffic. Each customer terminal (2) has a demultiplexer (22) arranged to receive multiplexed downstream traffic from the network (18), and to segregate the traffic between the first and second service unit.

Abstract: A head-end station for a passive optical network system arranged to transmit and receive TDMA frames having a header portion and a plurality of basic frames, each basic frame includes traffic bits and control bits. The head-end station includes a data transmitter which assembles and transmits downstream frames and also generates a diagnostic signal for transmission in a downstream frame, the station being switchable to a diagnostic mode in which it transmits the diagnostic signal in a downstream frame in the absence of other traffic, and also including a data receiver which receives upstream frames and detects a return of the diagnostic signal. In a preferred example, the head-end station may transmit a diagnostic signal in the header portion of each downstream frame. Also, in a test mode the transmit signal is looped back to the receiver to enable testing of the transmit receive function.

Abstract: A system for monitoring a network in which a station is connected to the network and includes a transmitter and a receiver. The transmitter outputs a signal modulated with outgoing traffic onto the network and the receiver receives a signal from the network modulated with incoming traffic. The station includes a monitoring circuit which introduces a variable delay in a signal from the transmitter and combines the delayed signal with the received signal so as to produce an output dependent upon the correlation of the signal from the transmitter and the received signal at the given delay. Preferably, the network is an optical network and the delay is introduced by a programmable delay line.

Abstract: A test apparatus is designed for use with a TPON system including a headend station connected via a fibre optic network to a plurality of terminations. The test apparatus is a self-contained unit including a connection for linking the apparatus to a termination, a first detection circuit which detects status signals generated by the termination, and a second detection circuit which detects alarm signals generated in the head-end station and transmitted to the termination in a downstream data frame. The test apparatus in response to the first and second test circuits provides an output which indicates the condition of the termination. In one example, a series of indicator lamps formed on the housing for the test apparatus are lit to provide the appropriate output.