Abstract: A packet processor whose processing capabilities are optimized by concurrently processing multiple packets within various pipelined stages. At each stage, multiple packets are processed via an internally pipelined sub-processor. In one embodiment, the packets are processed in a round robin fashion. When a particular packet is done processing at a particular stage, it may pass another packet whose processing is not complete, and move to a next stage. In another embodiment, a packet is processed until a conditional branch instruction or any other instruction causing a potential stall is encountered. If such an instruction is encountered, a next available packet is selected and processed instead of wasting processing cycles during the stall, or proceeding with the processing of the current packet based on a predicted result. The sub-processor resumes processing of the packet once the stall is over.

Abstract: A method of processing frames received at a sending port of a switching device for communication to a destination port includes storing in the switching device an offset value, a comparator value, and an expectant value; comparing information located at a position in a frame determined by the offset value with the comparator value to obtain an outcome; and processing the frame with the outcome. Processing the frame may include communicating the frame to a destination port or setting the priority of the frame. The offset and comparator values may be part of a filter that also includes an anchor value from which the offset value is measured and a mask value that masks the frame information before comparison with the comparator value. Where there are a multiple of filters in the switching device, the method may include combining the filter outcomes to obtain a filter group outcome; and processing the frame with the group outcome. Combining the filter outcomes may include logically combining their outcomes.

Abstract: A switching device for forwarding network traffic to a desired destination on a network, such as a telephone or computer network. The switching device includes multiple ports and uses a lookup table containing lookup keys to determine which port to forward network traffic over. The lookup tables are populated based on use. Consequently, the lookup tables on different ports contain different addresses. By storing only addresses that a port uses, each port's lookup table is unique to that port's characteristics. Additionally, aging techniques are used on both source and destination addresses in the lookup table so that stale entries are removed and memory is conserved.

Abstract: Multiple lookup engines stacked upon one another in a single data communication switch. The lookup engine at the top of the stack transmits its result to the neighboring downstream lookup engine which either validates and transmits the received result or its own result based on the quality of its match. The result preferably indicates an exact match, partial match, or no match. Although several lookup engines can return a partial match, an exact match preferably occurs in only one lookup engine. The comparison, validation, and transmission steps are repeated by each downstream lookup engine, with the lookup engine at the bottom of the stack validating and returning a final result to the packet processor. The returned final result reflects a search result with the highest match quality.

Abstract: An equalization method and apparatus for equalizing a plurality of input signals received on a multichannel link leverages shared equalization resources to generate dedicated tap coefficients for application to the signals and updates the dedicated tap coefficients upon measured degradation in the quality of the signals. The equalization method and apparatus achieves acceptable bit error rates with relatively low overhead.

Abstract: A switching device for forwarding network traffic to a desired destination on a network, such as a telephone or computer network. The switching device includes multiple ports and uses a lookup table to determine which port to forward network traffic over. The lookup table includes network addresses that are maintained in ascending or descending order. The lookup table also includes network address that differ in length. Fictitious network addresses may also be added to the lookup table to expedite searches in the lookup table. The fictitious network addresses are used in conjunction with a comparison field stored in the lookup table. The comparison field allows network addresses and collapsed network addresses (which represent groups of network addresses) to be stored within the same table. The collapsed network addresses allows for a reduction of overall lookup table size, thereby increasing the speed while reducing the cost of the switching device.

Abstract: Method and apparatus for detecting signal transfer errors in a digital logic system that might occur in a transfer medium between a source device and a destination device. The method includes sending a first diagnostic signal of one or more bits from the source device through the transfer medium to the destination device; comparing the first diagnostic signal received by the destination device with a second diagnostic signal within the destination device to determine if a signal transfer error has occurred; inverting the first diagnostic signal; sending the inverted first diagnostic signal from the source device through the transfer medium to the destination device; and comparing the inverted first diagnostic signal received by the destination device with the second diagnostic signal to determine if a signal transfer error has occurred. Two embodiments of the invention are disclosed.

Abstract: A switching device for forwarding network traffic to a desired destination on a network, such as a telephone or computer network. The switching device includes multiple ports and uses a lookup table to determine which port to forward network traffic over. The lookup table includes network addresses that are maintained in ascending or descending order. The switching device includes multiple binary search engines coupled in series including one or more precursor binary search engines and a final stage binary search engine. Together, the binary search engines perform an N iteration binary search. Additionally, a single search engine can perform multiple concurrent searches so that source and destination addresses can be obtained simultaneously and without wasted memory cycles.

Abstract: A packet switch includes a multiple of bidirectional ports that are each connected by dedicated signal paths to a multiple of memory subsystems that in turn are connected to shared memory within the switch. The signal path from each port carries a fragment of a data stream between the port and each memory subsystem. The ports send and receive data stream fragments in parallel from the memory subsystems. This parallel action reduces the bandwidth required of a memory subsystem by dividing the port's data stream among the multiple memory subsystems. In storing data for forwarding to another port, each memory subsystem selects on a time division basis in parallel the data stream fragments from the same port and stores them in memory. In retrieving data from memory for a port, each memory subsystem selects on a time division basis in parallel the same port to receive the data stream fragments read from memory.

Abstract: A switching device for forwarding network traffic to a desired destination on a network, such as a telephone or computer network. The switching device includes multiple ports and uses a lookup table to determine which port to forward network traffic over. The lookup table includes network addresses that are maintained in ascending or descending order. The switching device includes multiple binary search engines coupled in series including one or more precursor binary search engines and a final stage binary search engine. Together, the binary search engines perform an N iteration binary search. Additionally, a single search engine can perform multiple concurrent searches so that source and destination addresses can be obtained simultaneously and without wasted memory cycles.

Abstract: In a switching device such as a network switch having multiple ports and shared buffer memory, method and apparatus for regulating the amount of buffer memory requested by a port. The method includes determining a limit number of buffers that a port may use from the number of available buffers in memory and the number of buffers in memory currently in use by the port. The limit number and number of buffers currently is use are then compared, and the comparison is used to determine whether a buffer request by the port will be generated. In an illustrative embodiment, determining the limit number includes adding the number of available buffers in memory with the number of buffers in memory currently in use by the port to obtain a sum, and multiplying the sum by a port allocation factor. The port allocation factor may be set independently for each port. Apparatus within the switching device practices the method in accordance with the invention.

Abstract: A switching device for forwarding network traffic to a desired destination on a network, such as a telephone or computer network. The switching device includes multiple ports and uses a lookup table to determine which port to forward network traffic over. The lookup table includes network addresses that are maintained in ascending or descending order. The switching device includes multiple binary search engines coupled in series including one or more precursor binary search engines and a final stage binary search engine. Together, the binary search engines perform an N iteration binary search. Additionally, a single search engine can perform multiple concurrent searches so that source and destination addresses can be obtained simultaneously and without wasted memory cycles.