British Telecommunications Public Limited Company

British Telecommunications Corporation

Corning Incorporated

David Cotter

Martin C Tatham

David W Smith

Richard Wyatt

Julian Kazimierz Lucek

Keith J Blow

David Charles Wood

Alistair James Poustie

Kevin Smith

Nicholas J Doran

Derek Nesset

David C Rogers

Keith James Blow

Nicholas John Doran

In a communications network, expired packets are recognized and removed by comparing a phase value received with the packet and a phase value previously received via the network on a master node. The packet is discarded when the difference between the value exceeds a predetermined amount.

Communications network having mechanism for removal of time-expired packets from the network

In a communications network, a node receives a transit packet. The priority assigned to the transit packet is determined and when it has a low priority then the transit packet is removed and a higher priority packet is inserted in the resulting vacancy.

Optical communications network

There is provided an apparatus for processing a segment of x optical bit slots from a packet comprising y optical bit slots, each bit slot defining a respective one of first and second complementary logical states, within a time span shorter than or equal to the time for receipt of the packet. The apparatus including a segment replicator which generates serial copies of the segment of the packet, each copy residing within a respective word containing z bit slots, where z is equal to or greater than x; and a bit differential processor for processing successive bits of the successive copies of the segment in n successive processing steps, the product of n and z being less than or equal to y. The result of each processing step is output in sequence by the bit differential processor, the result of processing the segment being given by x successive bit slots of the output.

Bit differential processing

An optical regenerator suitable for use with optical signals has two stages. An incoming optical signal to be regenerated passes first through a data division stage. This divides the optical data stream into a number of data streams at a bit rate lower than the original optical signal. These data streams then pass to a regeneration stage. In the regeneration stage, there are a number of optical gates. Each gate receives one of the optical data streams at its control input. An optical clock stream at the lower or at a multiple thereof passes through the optical gates. The outputs of these optical gates are connected in common to the optical output of the regenerator and provide a bit-interleaved regenerated optical data stream at the output.

Optical regenerator for high bit-rate OTDM signals

A node in an optical communications network receives optical packets at its input. It determines a priority assigned to each optical packet. When the optical packet is a transit packet destined for another node then, if the packet is determined to have a relatively higher priority, it is output from the node via a continuous-flow transmission path. Other transmit packets having relatively lower priorities are sent via an alternative transmission path that may include queues or buffers resulting in a variable delay.

Communication network

In a communications network, which may be a broadband optical network, a packet is transmitted from a source node to a destination node on a looped signal path. A return signal, which may function as an acknowledgement of the original signal, is transmitted back to the source node from the destination node in the time slot which was occupied by the original packet.

Method and apparatus for transmitting a return signal in a loop network

A communications network, suitable, for example, for linking computer processors, is formed from a number of nodes and links. The nodes and links are configured as a multiplicity of directed trails. Each directed trail spans some only of the nodes, but in combination the directed trails span every node of the network. Packets are routed through the network by selecting the appropriate one of the directed trails which links the source node and destination node, and by outputting the packet at the source node onto the selected trail. The nodes throughout the network may switch between predetermined and prescheduled switching states, and a given trail may be selected by choosing appropriately the time slot in which the packet is put onto the network. The network may be a photonic network carrying optical packets.

Communications network

A packet is routed by &ldquo;dead reckoning&rdquo; on a network having a generally regular topology. The packet is received at a node where a local routing decision is made. The packet is output in a direction selected according to the routing decision. The packet carries in addition to a destination address a directional flag indicating explicitly the preferred direction of onward travel and the routing decision is made using this flag. Several flags may be used, corresponding to different dimensions of the network.

Dead reckoning routing of packet data within a network of nodes having generally regular topology

A packet carried on an optical network is routed by carrying out a logic operation on an address word carried in a packet header and a predetermined discriminator word. A routing decision is made in accordance with the result of the logic operation. The logic operation may be a bit-wise Boolean AND operation. An additional logic operation may be carried out with an additional discriminator word to determine whether the packet is destined for a remote region of the network. In this case, the packet may be steered directly to the remote region.

Growing community of inventors

Woodbridge, United Kingdom

David Cotter