Abstract: 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.

Abstract: The invention replicates a packet requiring high availability and transmits it from two or more ports of a switch, for example a wiring closet Layer 2 switch. The parent packet carries a unique sequence number. The copies of the packet each carry the parent packet's unique sequence number. Each copy of the packet then travels on separate pathways through routers (Layer 3 network devices). The pathways are maintained separate by assigning high costs in a LSP routing sense to links connecting the two paths, and by assigning low costs to links along the desired paths. The two identical packets converge on the destination station. The destination station accepts the first packet with a particular sequence number, and discards any later packets with the same sequence number. In the event that a link in one path has a catastrophic failure, then the packet travelling along the other path reaches the destination station and service remains operative without interruption.

Abstract: An apparatus and technique off-loads responsibility for maintaining order among requests directed to a same address on a split transaction bus from a processor to a split transaction bus controller, thereby increasing the performance of the processor. The present invention comprises an ordering circuit that enables the controller to defer issuing a subsequent (write) request directed to an address on the bus until a previous (read) request directed to the same address completes. By off-loading responsibility for maintaining order among requests from the processor to the controller, the invention enhances performance of the processor since the processor may proceed with program execution without having to stall to ensure such ordering. The ordering circuit maintains ordering in an efficient manner that is transparent to the processor.

Abstract: A method and system for testing a Layer 2 tunnel in a data communication network including a network device and a network manager are described. According to the method, a test invocation is received from the network manager at the network device. In response to receipt of the test invocation at the network device, a Layer 2 tunnel within the data communication network is tested, and a result of the test is reported to the network manager. The tests that may be conducted include a connectivity test to determine if a Layer 2 tunnel can be established and a responsiveness test to determine the propagation time of a Layer 2 tunnel. Advantageously, both compulsory and voluntary Layer-2 tunnels can be tested, thereby enabling all Layer 2 protocols (e.g., L2TP, L2F, and PPTP) to be supported.

Abstract: A multilevel infrared (IR) type security system prevents unauthorized use of a computer. A program resident on the computer implements a user-validation procedure. An IR key device carries a first serial number and an encryption key. A second serial number corresponds to a device internal to the computer. A mass storage device installed in the computer stores a validation record that includes an unencrypted portion and an encrypted portion, the unencrypted portion including a copy of the first serial number and the encrypted portion including a copy of said second serial number and a user personal identification number. The key device is coupled and interfaced with an infrared port on the computer by the user. The first serial number and the encryption key are read from the key device in order to gain authorized use of the computer. The key device may be decoupled from the computer after authorized use of the computer has been gained, and during operation of the computer.

Abstract: Method of updating dictionaries in a data transmission system wherein strings of characters have to be transmitted in a compressed form from the transmit device to the receive device, the transmit device having a transmit dictionary storing codewords associated with the strings of characters which are transmitted instead of the strings of characters, the receive device having a receive dictionary storing codewords associated with the strings of characters, both dictionaries being updated each time a new string of characters has to be transmitted so that their contents remain identical.

Abstract: Methods and systems are provided for communicating to multiple functions on a single adapter device over an external communications bus, where the external communications bus is configured so as to allow only a single access point to the external communications bus for each adapter device. Communications on the external communications bus are provided through the single access point to functions of a first type in the adapter device utilizing a function specific communications interface configured for communicating with functions of the first type. Communications on the external communications bus are also provided through the single access point to functions in the adapter device other than functions of the first type utilizing management capabilities of the function specific communications interface so as to provide communications with the functions of the second type without modifying the configuration of the function specific communications interface.

Abstract: Method and device for caching the IP header of a message being routed through a data transmission network wherein each node includes a route processor for computing a routing algorithm, a main memory for storing the message, a cache memory; and an IP header detection logic circuit for storing the header in the cache memory as the message is being stored in the main memory. Once the header has been stored in the cache memory, it can be read from the cache memory in order to compute the routing algorithm. The new header resulting from the routing computation is written into the cache memory and is then read from the cache memory when the message including the header and the message data is sent over the network.

Abstract: The present invention is directed to a high speed packet switching network and, in particular to a method and system for minimizing the time to establish a connection between an origin and a destination node. A path calculated at the time the connection is requested is recorded in a Routing Database and updated each time a modification occurs in the network. Furthermore, alternate paths for supporting non-disruptive path switch on failure or preemption, and new paths towards potential destination nodes can be calculated and stored when the connection set up process is idle. These last operations are executed in background with a low processing priority and in absence of connection request.

Abstract: A method is disclosed for making a selection on a pattern sequence depending on whether or not the sequence belongs to a routing set, the routing set having at least two keys. The selection is made in a single step by analyzing a selection word (CASE SELECT) identifying the routing set.

Abstract: In an infrared (IR) type computer security system, each authorized user is provided with an IR key device that holds a serial number and an encryption key. A validation record stored on the computer's hard disk contains an unencrypted key device serial number and an encrypted hard disk serial number. The user couples the key device to an infrared port on the computer prior to power-up or reset. A program implements a user validation procedure. The procedure permits entry past a first security level if the key device serial number matches the unencrypted number in the validation record. If the first level validation is successful, the procedure then uses the encryption key to decrypt a second serial number found in the stored validation record. The procedure permits entry past a second security level if the validation record is properly decrypted and the second serial number matches the decrypted number. Failure in any step disallows use to the computer.

Abstract: A data transfer flow control system for a packet communications system includes a plurality of nodes interconnected by transmission links. The rate at which a sender node transmits information to a destination node in a network is modified in accordance with congestion information returned to the sender node from nodes along the path of the transmission or from the information receiver. The rate change for information being sent from the sender node is modified based upon the amount of elapsed time occurring since the last rate change of the same type. In first and second examples, the rate change is implemented in accordance with exponential and linear relationships, respectively, between the modified flow rate and the elapsed time since the last rate change.

Abstract: A method for computing an ACK timing interval for an ACK timer in a protocol layer LLC type 2 session first measures a time interval between transmission of a frame by a source computer joined to a to a destination computer by an intermediate link, and receipt of a corresponding acknowledgment frame by the source computer from the destination computer. The two events at the source computer, starting a timer upon commencement of transmission of a frame or sequence of frames and the later reception of an acknowledge message indicating receipt of those frames, permits calculation of a measured time interval. The measured time interval is used to compute the bandwidth of the intermediate link. The required ACK timing interval for the ACK timer is then computed in response to the bandwidth, the number of bytes transmitted after starting the ACK timer, and the return time for an acknowledgment message.

Abstract: An improved group-based routing update technique allows limited per neighbor customization of routing update messages generated by an interdomain router for its neighboring peer routers within autonomous systems of a computer network. The technique may be employed when the neighboring peer routers share identical routing policies, but the routing update messages differ only in certain attributes with known locations and lengths. Appropriate values of the location and length attributes for each neighboring router are calculated and stored during a replication stage of the improved technique. Before each message is transmitted, the proper location and length attributes of the message are updated with the stored values for the respective neighbor.

Abstract: A flow control mechanism for use in a high speed packet switching network where calls are multiplexed on network trunks with each connection using a reserved amount of the total bandwidth. Data terminal equipments access the network via access nodes. Each access node includes a Leaky Bucket component which maintains a refillable token pool. Each time an incoming packet is received by the leaky bucket component, the number of available tokens is compared to two predetermined threshold values. If the number of tokens is less than the low threshold, acknowledgments of received packets are stopped, inducing an interruption of packets transmitted by the emitting terminals. Interrupting packet transmission will lead to a regeneration of the number of tokens in the token pool. If the number of tokens reaches the high threshold, acknowledgments are again generated to restore packet transmissions.

Abstract: 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.

Abstract: System for monitoring the performance of at least one line at a node of a digital communication network, such a system including a set of hardware registers associated with the line for registering line performance information associated therewith, a set of counters associated with the line, each counter defining a parameter depending on the line performance information, and a processing unit for, during a predetermined period of time, gathering the line performance information from the counters in a performance report to be sent to a network management unit. One table (22, 24 or 26) is associated with the line and stores all the data necessary to read the parameter for each counter of the associated set of counters with the line, and a processing machine (20) reads the table, sequentially computes the parameters defined by each counter by using the data stored in the table, and sequentially updates the counters.

Abstract: A system enables a consumer to generate a filtering program based on criteria set forth by a system operator during run time. During system operation, the operator selects appropriate filtering criteria from a display screen associated with a respective consumer. Each consumer implements filtering criteria in a filtering program that is registered with a distributor. The filtering program may include simple true or false tests, or more complex tests. The distributor compiles each filtering program during registration and thereafter dynamically loads the compiled program before executing filtering queries.

Abstract: The invention recognizes that a probability density function for fitting a model to a complex set of data often has multiple modes, each mode representing a reasonably probable state of the model when compared with the data. Particularly, sequential data such as are collected from detection of moving objects in three dimensional space are placed into data frames. Computation of the probability density function of the model state involves two main stages: (1) state prediction, in which the prior probability distribution is generated from information known prior to the availability of the data, and (2) state update, in which the posterior probability distribution is formed by updating the prior distribution with information obtained from observing the data. In particular this information obtained purely from data observations can also be expressed as a probability density function, known as the likelihood function.

Abstract: A communication network having a plurality of routers, each connected to host systems by LAN networks and interconnected by a switched network uses a shared or common IP and MAC address in the routers. Host systems on the same subnet use the shared or common IP address as their default gateway address when accessing host systems on another subnet.