Abstract: A multitasking computer system having multiple parallel and independently executing processors. Each processor has multiple pipeline stages. Each stage in the pipeline can be simultaneously executing a process. More processes than the sum of pipeline stages for all processors exist at any given time, which allows processes to migrate between processors and allows the processes queued at any one processor to increase, i.e., back up, momentarily without causing other processors to sit idle. Related to the ability to support at least as many processes as there are the sum of pipeline stages in all of the processors is the ability of the preferred embodiment of the present invention to migrate processes between processors. When a processor completes execution of an instruction for a particular process, the program counter for the process is incremented to point to the next instruction in the process. The process is then requeued by a scheduler.

Abstract: A method for filtering an internetwork packet wherein multiple paths to a destination network are provided. The method comprises the step of providing a forwarding list that comprises a plurality of entries selected by a user. The forwarding list indicates a plurality of possible paths to a selected destination. One of the entries is selected by the user as a primary entry that indicates a default path. When an internetwork packet is destined for the destination network is received, the packet is forwarded to the destination network via the default path if the primary entry indicates a valid path. Otherwise, the packet is forwarded to the destination network via another path as indicated by another entry. According to an alternative embodiment, a different forwarding list is provided for each subnetwork of a source network, and the forwarding list is selected based on the source address of the packet.

Abstract: A pipeline processor having an add circuit configured to execute separate atomic add instructions in consecutive clock cycles, wherein each separate atomic add instructions can be updating the same memory address location. In one embodiment, the add circuit includes a carry-save-add circuit coupled to a set of carry propagate adder circuits. The carry-save-add circuit is configured to perform an add operation in one processor clock cycle and the set of carry propagate adder circuits are configured to propagate, in subsequent clock cycles, a carry generated by the carry-save-add circuit. The add circuit is further configured to feedforward partially propagated sums to the carry-save-add circuit as at least one operand for subsequent atomic add instructions. In one embodiment, the pipeline processor is implemented on a multitasking computer system architecture supporting multiple independent processors dedicated to processing data packets.

Abstract: A method and apparatus for a node to automatically switch between half-duplex and full-duplex transmission in CSMA/CD networks characterized by a first and second device coupled over a communication link to allow communication of information and control signals between the first and second device. Each of the two devices include a transmit circuit and a receive circuit, wherein the first device begins to transmit information on a first communication circuit, the first communication circuit providing for communication of information between the first device and the second device, and the second device receives the transmitted information.

Abstract: A method and apparatus for generating a display containing information about both the local and remote traffic handled by an integrated router/hub is provided. An integrated router/hub routes local messages between devices on a first local area network, and routes remote messages between the first local area network and a second local area network. The integrated router/hub stores a first set of values related to the local messages, and a second set of values related to the remote messages. A network management station executes a network management application the includes instructions which cause the network management station to generate a display of the information stored in the integrated router/hub. In response to user input, the network management station requests the information from the integrated router/hub, receives the information from the integrated router/hub, and generates the display of the information. The display may include charts that illustrate statistics derived from the information.

Abstract: An apparatus which provides the user with an indication of the computer network's health. The indication is provided by a network management station on the computer network. The network management station has a distributable piece of code which instructs agents to gather diagnostic and status information. The network management station then evaluates the network specific diagnostic and status data gathered by the agents. Based on the evaluation, the network management station generates a representation of the computer network's functionality (i.e., its "health"). Thereby, the user can readily determine whether the computer network requires repairs.

Abstract: In a segmentation and reassembly module in a local area network switch module, a method and apparatus for storing fixed length data cells received from an ATM network in a plurality of memory buffers during the reassembly of the data cells in to a variable length data packet to be transmitted on an attached local area network.

Abstract: A method and apparatus are provided for grouping the network entities that belong to a network system into logical groups, and generating a display of the network based on the logical groups. In the highest level display, a single visual indicator, such as an icon, is used to represent each logical group. Thus, a display of the entire network system need only contain as many visual indicators as there are logical groups. Typically, the number of logical groups will be significantly less than the number of actual network resources. Consequently, entire large network systems may be displayed without crowding the display screen with small, difficult to read icons. The logical groups are formed based on the type of connections that exist between the various logical entities in the network. Site groups are formed by combining all local area network connections that connection common network entities. Region groups are formed by combining all wide area network connections that connect common network entities.

Abstract: A token ring network having virtual token rings comprised of one or more physical token rings. A media access control (MAC) layer device such as a bridge or switching hub has at least two ports assigned the same ring number such that token ring segments connected to the ports operate as though on the same physical token ring segment even though they are electrically isolated. All physical rings in the same virtual ring are considered to be in the same broadcast domain.

Abstract: A method of configuring a network. The network includes some physical devices, some hosts, and a network management tool. The method comprises the following steps. First, generate a set of leaf nodes. Each leaf node includes at least one physical device and connects to at least one host. Next, generate an adjacency matrix from said set of leaf nodes. Next, generate a set of interconnect nodes, the interconnect nodes connect the set of leaf nodes. Next, determine the resource availability for the set of interconnect nodes. Finally, configure the set of interconnect nodes and the set of leaf nodes after determining that sufficient resources are available.

Abstract: A method and apparatus for filtering data packets from a network device, such as a LAN switch, onto a network coupled thereto based on the content of the data packets. A pattern is defined and a forwarding action performed on data packets whose contents match or do not match the pattern, according to a specified condition. Filters may be configured on a per port basis, i.e., a filter can be applied to data packets entering or exiting a specific port on a networking device such as a LAN switch. A data packet received or transmitted at a port of a network device whose contents meet a condition specified by a filter may be processed in a number of ways: the packet may be forwarded to a normal destination port according to normal forwarding rules, forwarded to additional destination ports, forwarded to a monitor destination port, dropped, or subjected to another filter. The next filter may define a different forwarding action for data packets that do not meet the condition specified by the present filter.

Abstract: A method for searching for keys of arbitrary width in a table in a memory of a computer system by repeatedly executing lookup instructions on a lookup processor. The lookup processor executes a lookup instruction to find a key in a table. The execution of the lookup instruction results in a key being found, or a key not being found. If the key is not found, the process is requeued by a scheduler with the program counter register for the process pointing to the instruction immediately following the lookup instruction, i.e., the next instruction. In the event the key is found in the table, the entry in the table associated with the key contains the memory address of the next instruction to be executed. This memory address is loaded into the program counter register associated with the process in which the lookup instruction was executed. The scheduler requeues the process, later dequeues it, and the instruction pointed to by the program counter register is fetched by an instruction fetch unit.

Abstract: Editing the parameters for several network devices coupled to a computer network can be a cumbersome task. To simplify the task, a method of editing parameter settings for more than one network device using a graphical user interface is introduced. First, a set of network devices is displayed on a display screen. Then, a user selects a set of network devices to edit parameters for. Next, a list of parameters for the selected network devices is displayed on a display screen. The parameters that have the same value for all the selected network devices are displayed on the screen. However, parameters that do not have the same value for all the selected network devices are not displayed on the screen. Instead, the field is usually left blank. A user can edit the parameter settings displayed on the screen. When a parameter modification is approved, the modified parameter value is sent to all the selected network devices.

Abstract: A method for handling cache misses in a computer system. A prefetch unit fetches an instruction for execution by one of a plurality of coprocessors. When the preferred embodiment of the present invention experiences a cache miss in a prefetch unit, the process for which an instruction is being fetched is passed off to a memory processor which executes a read of the missing cache line in memory. While the process is executing in memory processor, or queued by the scheduler for execution of the same instruction, the prefetch unit continues to dispatch other processes from the its queue to the other processors. Thus, the computer system, including the processors, do not stall. Processors continue to execute processes. The prefetch unit continues to dispatch processes. When the memory read is completed, the process in which the cache miss occurred is rescheduled by the scheduler. The prefetch again attempts to fetch and decode the instruction and arguments.

Abstract: Heavily relied upon network devices require backup power systems. To efficiently allocate power, a highly programmable backup power system is desired. The present invention discloses a redundant power supply unit that provides backup power to network devices. The redundant power supply unit will supply power to the network devices in the case that their local internal power supplies fail. Furthermore, if there is a power outage from the utility company, the redundant power supply will supply power to the network devices from a internal battery pack. When the internal battery pack is engaged, the redundant power supply uses programmed control logic that controls how the power from internal battery pack will be allocated. Specifically, since the power from the batteries is limited, it can be used to power some network devices for a certain amount of time and other network devices for a longer amount of time.

Abstract: A method for filtering and forwarding local broadcast traffic across network boundaries. According to one embodiment, the method comprises the step of providing a broadcast list for a source network wherein the broadcast list includes at least one entry that specifies a network address. When a local broadcast packet is received from the source network, a copy of the local broadcast packet is made for each entry in the broadcast to produce a copied packet. The destination address of each copied packet is replaced with a corresponding destination address of a broadcast list to produce a modified packet, and the modified packets are transmitted such that the modified packets are delivered to networks specified by the broadcast list.

Abstract: Methods and apparatus providing for a switching hub in which an asynchronous transfer mode (ATM) switch is utilized as a backplane bus to which a plurality of LAN and ATM modules are coupled. Each LAN or ATM module is an autonomous switching module. Thus, for example, an Ethernet LAN module may receive Ethernet packets on one of its ports and transmit the packets out another one of its ports according to well known standards and techniques for bridging such packets, without the need for such packets to be translated into ATM cells and transmitted across the ATM switch backplane bus.

Abstract: The present invention relates to methods and apparatus providing for a switching hub in which an asynchronous transfer mode (ATM) switch is utilized as a backplane bus. Bus arbitration, i.e., allocation of bandwidth, on the bus for autonomous ATM and LAN switching modules coupled thereto is dynamically controlled according to the needs of the various modules. In particular, the present invention allows time division multiplexing of the bus under programmatic control such that each module, e.g., an Ethernet or Token Ring module, is allowed a desired number of cell slots on the bus during which to transfer data, which the module has translated into ATM cells, across the bus.

Abstract: A system of discovering the active topology of the LANs (local area networks) connected via any apparent bridges that conform to the IEEE 802.1D standard. A discovered active topology of the present invention consists of the active bridges, the LANs and the NMMs (network management modules) that constitute the bridged LAN. The system of the present invention advantageously utilizes the standard (IEEE 802.1D) defined behaviors of transparent bridges to discover the active topology. In so doing, the present invention does not require the bridges to issue any special proprietary frames for development of the active topology. The IEEE 802.1D conforming bridges have the property of forming a path between two conversing end stations. If the two end stations reside in adjacent LANs, the path between these two LANs only has the connecting bridge and no other LAN in between.

Abstract: A method and apparatus for controlling data flow within a switching device are provided. The switching device includes a cell-switched backplane. Both packet switched and cell switched network interface cards may be coupled to the cell-switched backplane. A destination tag is created for each unique destination port and for each unique set of destination ports. The destination tags are used to index a master destination tag table. The entry of the master destination tag table that corresponds to a given destination tag includes a destination mask that indicates which ports are destination ports the given destination tag. Local tables are built and maintained within each network interface card based on the information contained in the master destination tag table. When a network interface receives data from an external device, the network interface determines the destination tag associated with the data.