Bell Communications Research, Inc.

At&t Bell Laboratories

James N Giacopelli

Chester M Day, Jr

Thomas M Taylor

Walter D Sincoskie

Liang T Wu

William S Marcus

James D McElroy

Morgan Littlewood

Nian-Chyi Huang

Howard E Bussey, Jr

A cell for use in a packet switching network. The cell comprises an input for receiving a packet including a destination address and first and second outputs. The cell includes a selection circuit for connecting the input with the first output or the second output depending on whether a specific bit occupying a predetermined position in the packet address is a logic '1' or a logic '0'. Illustratively, the specific bit is the first bit after a start bit of the packer and each of the cells includes means for rotating the specific bit to the end of the address. This is especially useful for implementing a banyan network wherein the k.sup.th column of cells the routing decision is based on the k.sup.th most significant bit of the address, as the address bit rotation mechanism can be used to ensure that the first bit after the start bit of a packet is the k.sup.th most significant address bit. Preferably, each of the cells may be disabled in response to a disabling signal so that the input is connected to the first or second output independently of the logic value of the specific bit. This permits a packet switching network to be formed from interconnected horizontal and vertical stacks of chips wherein selected cells are disabled.

Switching cell for packet switching network

A Batcher-banyan network which may be implemented using only two different IC chip designs is disclosed. The chips comprising the Batcher banyan network are arranged in adjacent horizontal and vertical stacks to minimize the lengths of electrical conductors connecting the chips.

Batcher-banyan network

A novel packet switch architecture is disclosed. The packet switch utilizes internal queuing (i.e. recirculation loops) and output queuing (i.e. multiple paths to each destination) to provide a packet switch which offers superior performance in comparison to a packet switch which utilizes either of these queuing strategies alone. The combination of recirculation and output queues have complimentary effects. The output queuing reduces the number of recirculation loops needed and recirculation reduces the bandwidth requirements for an output buffered switch.

Broadband packet switch with combined queuing

A novel packet switch architecture is disclosed. In the novel packet switch, inputs are dynamically allocated between newly arriving and recirculating packets to make maximum use of available bandwidth while simultaneously resolving output port conflicts.

Packet switch with dynamic allocation of inputs

A full access, non-blocking, self-routing packet switch based on a Batcher sorting network is disclosed. Fake place holding packets are utilized along with a conflict resolution scheme to insure that during each packet switch cycle a packet is routed from each input port to each output port. The use of fake place holding packets insures that real packets which contain user data can be routed to the outputs having the addresses contained in their packet headers.

Non-blocking, self-routing packet switch

A time-division circuit switch which serves as a cross connect for time multiplexed signals including frames subdivided into slots serves to cross-connect input and output lines on a slot-by-slot basis. The circuit utilizes a self-routing packet switching network. An input interface attached to each input line converts incoming slots into fixed length packets which can be routed through the self-routing switching network in a synchronous manner. An output interface coupled to each output line reconverts the packets into slot/frame format. To prevent blocking, the self-routing packet switching network runs at a faster rate than the input and output lines of the switch.

Time division circuit switch

A stored program energy control system operates with the control of a telephone communications system to improve its energy efficiency by removing power from station sets and their associated visual indicators when they are inactive. Inactive station sets are identified by establishing minimal intervals of nonuse to define the inactive status. The energy control system responds to events like incoming calls and switchhook activity to restore power to the station set. Since energy is applied to a station set only when precisely needed, the overall energy drain of the system is greatly reduced.

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Flanders, NJ, United States of America

James N Giacopelli