Cisco Technology, Inc.

Kenneth Michael Key

Michael L Wright

Darren R Kerr

William E Jennings

Scott Nellenbach

John William Marshall

Kwok Ken Mak

Xiaoming Sun

William Fredenburg

Kenneth Harvey Potter, Jr

Jeffery B Scott

Edward D Paradise

L Duane Richardson

A technique implements a novel high-speed high-density packet buffer utilizing a combination of high-speed and low-speed memory devices. The novel packet buffer is organized as a plurality of FIFO queues where each FIFO queue is associated with a particular input or output line. Each queue comprises a high-speed cache portion that resides in high-speed memory and a low-speed high-density portion that resides in low-speed high-density memory. The high-speed cache portion contains FIFO data that contains head and/or tail associated with the novel FIFO queue. The low-speed high-density portion contains FIFO data that is not contained in the high-speed cache portion.

System and method for operating a packet buffer in an intermediate node

A programmable processing engine processes transient data within an intermediate network station of a computer network. The engine comprises an array of processing elements symmetrically arrayed as rows and columns, and embedded between input and output buffer units with a plurality of interfaces from the array to an external memory. The external memory stores non-transient data organized within data structures, such as forwarding and routing tables, for use in processing the transient data. Each processing element contains an instruction memory that allows programming of the array to process the transient data as processing element stages of baseline or extended pipelines operating in parallel.

Programmable arrayed processing engine architecture for a network switch

A processor complex architecture facilitates accurate passing of transient data among processor complex stages of a pipelined processing engine. The processor complex comprises a central processing unit (CPU) coupled to an instruction memory and a pair of context data memory structures via a memory manager circuit. The context memories store transient 'context' data for processing by the CPU in accordance with instructions stored in the instruction memory. The architecture further comprises data mover circuitry that cooperates with the context memories and memory manager to provide a technique for efficiently passing data among the stages in a manner that maintains data coherency in the processing engine. An aspect of the architecture is the ability of the CPU to operate on the transient data substantially simultaneously with the passing of that data by the data mover.

Architecture for a processor complex of an arrayed pipelined processing engine

A processor isolation technique enhances debug capability in a multiprocessor circuit. A bypass register has a bit location which may indicate that a processor is to be bypassed. A code entry point is selected to permit a downstream processor to do the work of the bypassed processor. The processors may be arrayed in a pipeline.

Processor isolation technique for integrated multi-processor systems

A technique for implementing a novel high-speed high-density packet buffer utilizing a combination of high-speed and low-speed memory devices. The novel packet buffer is organized as a plurality of first-in-first-out (FIFO) queues where each FIFO queue is associated with a particular input or output line. Each queue comprises a high-speed cache portion that resides in high-speed memory and a low-speed high-density portion that resides in low-speed high-density memory. Each high-speed cache portion contains FIFO data that contains head and/or tail information associated with a corresponding FIFO queue. The low-speed high-density portion contains FIFO data that is not contained in the high-speed cache portion. A queue identifier (QID) directory refills the high-speed portion of one or more queues with data from a corresponding low-speed portion. Queue head start and end offsets are used to determine whether a corresponding queue is empty.

System and method for operating a packet buffer

A technique is provided for use in computerized modeling of an electronic system. The technique bases simulation of the system's operation (e.g., timing operation) upon both actual physical characteristics of a part of the system, and hierarchical analysis-based models of the rest of the system.

Electronic system modeling using actual and approximated system properties

The present invention incorporates a technique that enables the processing of memory requests without requiring memory devices that support a request identifier (ID). The present invention maintains an association between a request identifier and a first memory request issued by a requestor and directed to a memory location. The first memory request contains an address corresponding to the memory location. A memory device corresponding to the address is selected. A second memory request without the identifier is issued to the selected memory device to access information stored at the location. The information is received from the memory device and associated with the request identifier.

System and method for processing memory requests

A processor complex architecture facilitates accurate passing of transient data among processor complex stages of a pipelined processing engine. The processor complex comprises a central processing unit (CPU) coupled to an instruction memory and a pair of context data memory structures via a memory manager circuit. The context memories store transient &ldquo;context&rdquo; data for processing by the CPU in accordance with instructions stored in the instruction memory. The architecture further comprises data mover circuitry that cooperates with the context memories and memory manager to provide a technique for efficiently passing data among the stages in a manner that maintains data coherency in the processing engine. An aspect of the architecture is the ability of the CPU to operate on the transient data substantially simultaneously with the passing of that data by the data mover.

A processor isolation technique enhances debug capability in a highly integrated multiprocessor circuit containing a programmable arrayed processing engine for efficiently processing transient data within an intermediate network station of a computer network. The technique comprises a mechanism for programming a code entry point for each processor of a processor complex utilizing a register set that is accessible via an out-of-band bus coupled to a remote processor of the engine. The programmable entry point mechanism operates in conjunction with a bypass capability that passes transient data through a processor complex that is not functional, not running or otherwise unable to process data. Another aspect of the debug technique involves the ability to override completion control signals provided by each processor complex in order to advance a pipeline of the processing engine.

Processor isolation method for integrated multi-processor systems

Programmable processing engine for efficiently processing transient data

Architecture for a process complex of an arrayed pipelined processing engine

A technique is provided for use in testing replicated components (e.g., identical circuit components) of an electronic device for defects. In one aspect of this testing technique, the same test inputs may be broadcast, in parallel, from a single test interface to each of the replicated components of the electronic device under test. Respective test outputs generated by the replicated components in response to the test inputs may be supplied to a comparator, comprised in the electronic device, that compares the respective test outputs to each other and generates a fault signal if corresponding test outputs are not identical. This fault signal may be supplied to an external test interface pin of the single test interface, and its assertion may indicate that one or more of the replicated components may be defective. The respective test outputs may be multiplexed to permit output via an external interface of respective test outputs from a selected component. These respective test outputs may be compared to expected values therefor whereby to determine presence and/or nature of defects in the replicated components.

Testing of replicated components of electronic device

A multi-port switching device architecture decouples decode logic circuitry of each port of a network switch from its respective state machine logic circuitry and organizes the state machine logic as pools of transmit/receive engine resources that are shared by each of the decode logic circuits. Intermediate priority logic of the switching device cooperates with the decode logic and pooled resources to allocate frames among available resources in accordance with predetermined ordering and fairness policies. These policies prevent misordering of frames from a single source while ensuring that all ports in the device are serviced fairly.

Pooled receive and transmit queues to access a shared bus in a multi-port switch asic

A synchronization and control system for an arrayed processing engine of an intermediate network station comprises sequencing circuitry that controls the processing engine. The processing engine generally includes a plurality of processing element stages arrayed as parallel pipelines. The control system further includes an input header buffer (IHB) and an output header buffer (OHB), the latter comprising circuitry for receiving current transient data processed by the pipelines and for decoding control signals to determine a destination for the processed data. One destination is a feedback path that couples the OHB to the IHB and returns the processed data to the IHB for immediate loading into an available pipeline.

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Raleigh, NC, United States of America

Kenneth Michael Key