Abstract: A method and apparatus for dynamically shifting between switching and routing packets efficiently to provide high packet throughput. The present invention provides a method for transmitting packets between an upstream node and a downstream node in a network that utilizes flow classification and labelling to redirect flows. The method includes the steps of establishing default virtual channels between the upstream node and the downstream node, receiving a packet at the downstream node, performing a flow classification at the downstream node on the packet to determine whether the packet belongs to a specified flow that should be redirected in the upstream node, selecting a free label at the downstream node, and informing the upstream node that future packets belonging to the specified flow should be sent with the selected free label attached. Other embodiments of the present invention include a basic switching unit and a switch gateway unit for use in a system for transmitting packets in a network.

Abstract: Reactive congestion control in an asynchronous transfer mode (ATM) network where the network is formed by the interconnection of nodes each including a forward path for transfer of information from source to destination through the network and a return path for returning congestion control signals. Each source includes a modifiable issue rate unit which issues forward information signals at different rates for virtual channels in response to the presence and absence of congestion signals received on the return path.

Abstract: Asynchronous Transfer Mode Local Area Network (ATM LAN). The ATM LAN is implemented as a set of MAC entities which share a common group address space for the purposes of establishing multicast connections. Each station has one or more ATM MAC entities per physical connection to an ATM network. The network ATM LAN service provides the station with ATM LAN configuration information needed for ATM MAC operation. Included in this information is the number of ATM LANs the network has configured for that station.

Abstract: Reactive congestion control in an asynchronous transfer mode (ATM) network where the network is formed by the interconnection of nodes each including a forward path for transfer of information from source to destination through the network and a return path for returning congestion control signals. Each source includes a modifiable issue rate unit which issues forward information signals at different rates for virtual channels in response to the presence and absence of congestion signals received on the return path. When congestion occurs, for example, a queue exceeds a threshold, a request is made to send congestion signals, in the form of backward explicit congestion notification (BECN) cells, back to the sources of the virtual channels currently submitting traffic to the queue. On receipt of a BECN cell on a particular virtual channel, a source reduces it transmission rate for the indicated virtual channel.

Abstract: Asynchronous Transfer Mode Local Area Network (ATM LAN). The ATM LAN is implemented as a set of MAC entities which share a common group address space for the purposes of establishing multicast connections. Each station has one or more ATM MAC entities per physical connection to an ATM network. The network ATM LAN service provides the station with ATM LAN configuration information needed for ATM MAC operation. Included in this information is the number of ATM LANs the network has configured for that station.

Abstract: A self-routing switching element in a packet switch functions in a packet synchronous mode in which a plurality of the incoming packet signals are switched by the switching element concurrently during a common time period. For each incoming packet signal received during the common time period, the switching element control includes detector circuitry to detect that one of the inputs has an incoming packet signals for transmission to one of the outputs, includes determining circuitry for determining if the one of the output modules will accept the incoming packet signals, and includes enable circuitry, responsive to the determining circuitry, for enabling the acceptance of the incoming packet signal by the output module for transmission to the output. The control is distributed throughout the switching element in output modules, one module for each output from the switching element.

Abstract: A communication unit for concurrently processing cells in an asynchronous transfer mode (ATM) network. Packets are segmented into a plurality of cells concurrently for a plurality of channels for transmission over the (ATM) network. Cells received from the ATM network are reassembled concurrently for the plurality of channels. Pipelined processing units are employed for segmentation and for reassembly each having logic control, control memory, and data memory. The segmentation unit control memory stores two-dimensional queues with first dimension rate queues for queueing descriptors for cells of different channels having cells to be transmitted and with second dimension channel queues for each channel having a cell descriptor in the rate queue.

Abstract: A self-routing switching element in a packet switch functions in a packet synchronous mode in which a plurality of the incoming packet signals are switched by the switching element concurrently during a common time period. For each incoming packet signal received during the common time period, the switching element detects that one of the inputs has an incoming packet signal for transmission to one of the outputs, determines if the one of the output modules will accept the incoming packet signals, and responsive to the determination, enables the acceptance of the incoming packet signal by the output module for transmission to the output. The control circuitry is distributed throughout the switching element in output modules, one module for each output from the switching element.

Abstract: A zoom lens drive mechanism, for translationally driving and positionally locating a lens subgroup of a zoom lens to a zooming position along an optical axis of the zoom lens, comprises a base ring member having an aperture concentrically defined about the optical axis of the zoom lens and a drive ring member rotatably mounted on the base member for concentric rotation about the optical axis with axial constraint. A translatable lens subgroup ring member is suspended concentrically from the base and drive ring members by means of rods independently coupled at first ends thereof to the base and drive ring members and joined at second ends thereof to a common pivot point on the translatable ring member. Alternative split ball joint arrangements are described for coupling the suspension rods to the translatable ring member.

Abstract: A zoom lens includes a lens group mounted in a cam barrel mechanism which includes a fixed barrel with a cam barrel rotationally mounted thereon. The lens group has a pin which projects through an axially extending clearance slot in the fixed barrel and a compliant feature on the pin removes the clearance between the pin and the slanted cam slot in the cam barrel so that as the cam barrel is rotated the lens group translates axially within the fixed barrel. The fixed barrel has an endcap with array of centering orifices mounted thereon and a beveled surface which is engaged by an outboard edge of the cam barrel. The cam barrel is urged against the endcap by a wave washer disposed between the cam barrel and a base. Radially disposed with respect to the cam barrel are a pair of spaced lugs and a bowed sheet spring which engages the cam barrel to urge the cam barrel against the lugs. The wave washer and bowed sheet spring positively locate the cam barrel with zero clearance.

Abstract: A compact camera comprises a flash unit adapted to be flipped up from a camera body for use and flipped down towards the camera body for storage and having a viewfinder opening for viewing a subject to be photographed, and an elongate resiliently flexible supporting part for the flash unit constrained to be flexed longitudinally in opposite directions when the flash unit is flipped up and down to operate as an overcenter spring for urging the flash unit alternatively to flip up or down and having a viewfinder opening arranged to be located behind the viewfinder opening of the flash unit when the flash unit is flipped up. According to the invention, a non-flexible lens element is connected to the flexible supporting part over its viewfinder opening but only at in-line points spaced apart laterally across the supporting part, as opposed to longitudinally along the supporting part, to prevent the lens element from interfering with flexing of the supporting part longitudinally.

Abstract: An element, such as a lens, is mounted on an element holder, such as a lens holder, so as to be constrained with a clearance-free, exact centering fit. The element has three radial faces spaced 120.degree. apart with respect to the center of the element, and the element holder has three abutments spaced 120.degree. apart with respect to a center point about which the abutments are distributed. Upon seating the element in the element holder with the radial faces and abutments in engagement, the element is constrained with the center points of the element and element holder in alignment. The radial faces and abutments are held in engagement by a retainer which also holds the element on the element holder. In accordance with one embodiment of the invention, the element is a plastic lens, and the element holder is a lens barrel, the lens being retained with clearance within the lens barrel by a retaining ring.

Abstract: A determining unit in a computer, communication of other system for determining which one of a plurality of requests by competing input signals is to be honored. The determining unit includes a priority and an arbiter unit with a plurality of stages of arbiter blocks cascaded together from arbiter blocks in a first stage to arbiter blocks in a last stage in a binary tree. The forward output signals from blocks in one stage connect as forward input signals to blocks in a next stage and reverse output signals from blocks in one stage connect as reverse input signals to blocks in a previous stage.

Abstract: A self-routing switching element in a packet switch functions in a packet synchronous mode in which a plurality of the incoming packet signals are switched by the switching element concurrently during a common time period. For each incoming packet signal received during the common time period, the switching element detects that one of the inputs has an incoming packet signal for transmission to one of the outputs, determines if the one of the output modules will accept the incoming packet signals, and responsive to the determination, enables the acceptance of the incoming packet signal by the output module for transmission to the output. The control circuitry is distributed throughout the switching element in output modules, one module for each output from the switching element.

Abstract: Mounts for plastic lens elements of differing diameters or materials include a separate V-block for mounting each lens element, wherein the V-blocks for lens elements of a smaller diameter converge at angles less than V-blocks for lens elements of a larger diameter, the angles of convergence being selected so that the centers of the lens elements remain aligned with an optical axis perpendicular to both of the lens elements upon thermal expansion of the lens elements.

Abstract: The switching element (16) comprises a plurality of selectors (32) each having an input for a tagged packet signal and a plurality of arbiters (34) each having an output for a transmitted packet signal. Between each selector (32) and each arbiter (34) is a signal path connection. Each arbiter (34) selects the first received packet signal and prohibits transmission from all other selectors by assertion of a busy signal until transmission of the first received packet signal is completed. An asynchronous time switch having a switching fabric made up of such elements (16) copes with the maximum delay requirements of voice class signals by priority of selection over other classes of signals. Increased throughput is attained by means of multiple switch fabric planes and by use of flooding. The latter technique involves sending copies of a packet signal along all possible paths to a desired output, all but one copy failing at arbiters (34) within the switch plane fabric or at a switch plane arbiter (24).

Abstract: To effect transfer of messages between data units (1-4, 5-8) a switching network of binary distributors (21-24, 31-38) and concentrators (41-48, 51-54) is used. For each distributor in the network the message is preceded by a respective single data bit which is absorbed in the switching system. Thus at the message destination all addressing bits have been absorbed, only the required message being received. Concentrators have both input paths enabled to their respective output paths except when a message is passing through the concentrator when the non-transmitting path is disabled.Any message arriving at a blocked concentrator is lost. Accordingly an acknowledging system uses a reverse path set up in parallel with the forward path to acknowledge receipt of the message. Alternatively the reverse path may be used to return a message fail indication from a blocked concentrator.

Abstract: An electrical connector-switch for use underwater is in two halves. Each half includes a tubular casing to which respective external electrical leads are connected, for a power supply to one half and an output from the other half. Each half also includes a core. The two casings can be joined together and the two cores joined together end-to-end, so that the two cores can slide as one member within the two casings for switching purposes. Electrical contacts on one of the cores switchably interconnect the external leads of the two casings in one end position of the two cores. Seals between the cores and the casings keep the water out, both when the casings and cores are joined together and when they are not joined together, so that connection and disconnection and switching are all possible underwater.