Abstract: A switching device comprising a plurality of ingress ports and a plurality of egress ports. The switching device is arranged to receive data packets through said ingress ports and to forward received data packets to respective ones of said egress ports. The switching device is further arranged to: determine a first time at which a first cell of a selected data packet is to forwarded to one of said egress ports, determine a further time at which a respective further cell of the selected data packet is to be forwarded to said one of said egress ports, store data indicating that said respective further cell is to be forwarded at said determined further time, forward said first cell at said first time, and forward said further cell of said selected data packet at said determined further time.

Abstract: A switching device comprising a plurality of ingress ports and a plurality of egress ports. The switching device is arranged to receive data packets through said ingress ports and to forward received data packets to respective ones of said egress ports. The switching device is further arranged to: determine a first time at which a first cell of a selected data packet is to forwarded to one of said egress ports, determine a further time at which a respective further cell of the selected data packet is to be forwarded to said one of said egress ports, store data indicating that said respective further cell is to be forwarded at said determined further time, forward said first cell at said first time, and forward said further cell of said selected data packet at said determined further time.

Abstract: A switching device comprising a plurality of ingress ports and a plurality of egress ports. The switching device is arranged to receive data packets through the ingress ports and to forward received data packets to respective ones of the egress ports. The switching device is further arranged to determine a first time at which a first cell of a selected data packet is to be forwarded to one of the egress ports, determine a further time at which a respective further cell of the selected data packet is to be forwarded to one of the egress ports, store data indicating that the respective further cell is to be forwarded at the determined further time, forward the first cell at the first time, and forward the further cell of the selected data packet at the determined further time.

Abstract: A method of queuing data packets, said data packets comprising data packets of a first packet type and data packets of a second packet type. The method comprises grouping received packets of said first and second packet types into an ordered series of groups, each group comprising at least one packet, maintaining a group counter indicating the number of groups at the beginning of the series of groups comprising only packets of the second packet type, and transmitting a packet. A packet of the second packet type is available for transmission if but only if the group counter is indicative that the number of groups at the beginning of the series of groups comprising only packets of the second packet type is greater than zero.

Abstract: A switching device comprising at least one ingress port and at least one egress port. The switching device is arranged to receive data packets through the at least one ingress port and to forward received data packets to respective ones of the at least one egress port. The switching device further comprises a primary buffer arranged to store data packets received via at least one of the least one ingress ports and a secondary buffer associated with the primary buffer. The switching device is adapted to select a data packet from the primary buffer and if but only if the secondary buffer satisfies a least one first predetermined criterion, transfer the selected data packet to the secondary buffer.

Abstract: A method of switching data packets between an input and a plurality of outputs of a switching device. The switching device comprises a memory arranged to store a plurality of data structures, each data structure being associated with one of said outputs. The method comprises receiving a first data packet at said input, and storing said first data packet in a data structure associated with an output from which said data packet is to be transmitted. If said first data packet is intended to be transmitted from a plurality of said outputs, indication data is stored in each data structure associated with an output from which said first data packet is to be transmitted, but said first data packet is stored in only one of said data structures. The first data packet is transmitted from said data structure to the or each output from which the first data packet is to be transmitted.

Abstract: A switching device comprising a plurality of ingress ports and a plurality of egress ports. The switching device is arranged to receive data packets through said ingress ports and to forward received data packets to respective ones of said egress ports. The switching device is further arranged to: determine a first time at which a first cell of a selected data packet is to forwarded to one of said egress ports, determine a further time at which a respective further cell of the selected data packet is to be forwarded to said one of said egress ports, store data indicating that said respective further cell is to be forwarded at said determined further time, forward said first cell at said first time, and forward said further cell of said selected data packet at said determined further time.

Abstract: A switching device comprising at least one ingress port and at least one egress port. The switching device is arranged to receive data packets through said at least one ingress port and to forward received data packets to respective ones of said at least one egress port. The switching device further comprises a primary buffer arranged to store data packets received via at least one of said at least one ingress ports and a secondary buffer associated with the primary buffer. The switching device is adapted to select a data packet from said primary buffer and if but only if said secondary buffer satisfies a least one first predetermined criterion, transfer said selected data packet to said secondary buffer.

Abstract: A method of switching data packets between an input and a plurality of outputs of a switching device. The switching device comprises a memory arranged to store a plurality of data structures, each data structure being associated with one of said outputs. The method comprises receiving a first data packet at said input, and storing said first data packet in a data structure associated with an output from which said data packet is to be transmitted. If said first data packet is intended to be transmitted from a plurality of said outputs, indication data is stored in each data structure associated with an output from which said first data packet is to be transmitted, but said first data packet is stored in only one of said data structures. The first data packet is transmitted from said data structure to the or each output from which the first data packet is to be transmitted.

Abstract: A method of queuing data packets, said data packets comprising data packets of a first packet type and data packets of a second packet type. The method comprises grouping received packets of said first and second packet types into an ordered series of groups, each group comprising at least one packet, maintaining a group counter indicating the number of groups at the beginning of the series of groups comprising only packets of the second packet type, and transmitting a packet. A packet of the second packet type is available for transmission if but only if the group counter is indicative that the number of groups at the beginning of the series of groups comprising only packets of the second packet type is greater than zero.

Abstract: A pretensioner for use with a retractor for a vehicle safety restraint to rapidly take up slack in a safety belt system at the onset of a crash situation so as to more correctly and securely restrain the vehicle occupant and to more correctly position him for maximum effect of an inflatable safety device such as an air bag. The pretensioner comprises a piston-cylinder arrangement in which a piston is driven along the inside of a cylinder under force provided, for example, by a spring or by a gas generator. The pretensioner has a resilient seal around the piston and the cylinder to provide load limiting at the start of the pretensioner stroke. Safety arrangements are provided for ensuring that the pretensioner is not activatable before installation in the vehicle, and the gas generator is constructed to ensure that there are no loose parts after detonation, which could cause damage. A bearing for the cylinder is provided for use when the piston-cylinder forms the crash sensor.