Abstract: An ATM switch includes one or more adapters having input ports and/or output ports and a switching fabric for switching Asynchronous Transfer Mode (ATM) cells received at the input ports to the output ports. To maintain switch throughput, cells are categorized either as real time (high priority) or non-real time (lower priority) cells. High priority cells are processed using a first set of cell processing logic at a rate at least equal to the rate at which the cells are received on the input ports. Lower priority cells are processed using a second set of cell processing logic only when no high priority cells are being processed.

Abstract: The present invention provides a data processing system, and method of operation of such a system, for creating a surface on a model of a 3D object, the model being stored as data in a storage device. The system comprises input means (10) for enabling a user to define lines representing features of the object, the lines being stored as model data in the storage device (40), and means (30, 50) to generate and display an image representing the model from the model data. Further the system is characterised by: identification means (60) for identifying data representing a plurality of the lines that form a first closed loop consisting of edges meeting at nodes, and for retrieving such data from the storage device (40); and processing means (20) for generating data defining a series of additional loops to represent a candidate surface bound by the first closed loop.

Abstract: To enhance the security provided by data encryption in a data communication network, encryption/decryption keys are changed periodically at the source and destination nodes for an established connection. A destination node must know not only the value of any new key but also when to begin using that key to decrypt received data packets. Synchronization (making sure a data packet is decrypted using a decryption key correlated with the encryption key used to encrypt the same packet) is achieved through the use of marker cells, which are special purpose cells. When a source node decides to activate a new key, previously sent to and stored at the destination node, a marker cell is transmitted by the source node to the destination node. When the destination node recognizes the marker packet, it discards it and activates the previously received key for use in decrypting subsequently received packets.

Abstract: In an Open System Interconnection (OSI) environment, an agent Common Management Information Protocol (CMIP) platform maintains an up to date tree of all of the Managed Object Instances (MOIs), in order to perform scoping functions. The agent platform receives a message from an OSI manager which includes a base MOI and levels below the base MOI to receive the message. The agent platform recurses through the tree below the base MOI to determine which MOIs should receive the message. If the message is delete, the children of MOIs to be deleted are also deleted. The children of undeletable MOIs are not deleted. A current, accurate tree is maintained by the agent platform, which can register a new MOI in the tree when a valid request is received from the MOI or the manager. The agent platform can also deregister an MOI upon valid request from the agent associated with the platform.

Abstract: A method and an apparatus to calculate in an intermediate node of a communication network, the new Frame Check Sequence (FCS) appended to a data bits message which has been modified in said intermediate network node. The invention is useful for high speed networks where the transit delay needs to be optimized in the network along with the computing resources in the intermediate network nodes in terms of computer cycles and memory size. The invention consists in calculating the difference between the FCS using the difference between the modified fields in the message and the distance in bits between the end of the modified field and the end of the message; the calculation consists in differentiating `short messages` in the data flow and to provide an optimized processing for the short messages, the processing for larger messages being based on this first optimized processing.

Abstract: Dynamic address assignment and reconfiguration of serially connected addressable device components of a network system using interchangeable cables terminated by plugs. Successive pairs of the devices are coupled with identical cables having the same offset cross-connected wiring between the terminating plugs, but which establish a unique address for the device to which connected depending on the position of the device in a chain of connected devices without requiring changes to the devices per se, e.g., jumpers or switches. The bus structure requires only a single port per device and removal, failure, or replacement of a device does not affect nor impair the proper operation of the other devices.

Abstract: A technique for permitting continued use of IP (Internet Protocol) routing protocols in an Asynchronous Transfer Mode (ATM) network is implemented in each ATM system having route-computing responsibilities. When a call setup request is received, the routing system determines, from the ATM address of the target system, whether a routing protocol must be implemented. If a routing protocol must be implemented, data in an ACN (ATM Cluster Number) field and an HN (Host Number) field in the target ATM address is read and is imported into an IP-format address. This IP-format address is used in implementing the IP routing protocol.

Abstract: A data switching device, such as an ATM or Asynchronous Transfer Mode switch, includes a switching fabric with multiple input and output leads. The device also includes at least one input adapter for receiving data cells on each of a number of input ports and at least one output adapter for delivering data cells switched through the switching fabric to a target port in a set of output ports. Error and format checks are performed on incoming cells and counts are kept of the number of good cells and invalid cells received on a particular input port. To reduce hardware costs, the counts are kept in a random access memory which is shared among the input ports. Several storage locations are allocated to each input port to maintain the necessary counts.

Abstract: The techniques required to switch an ATM cell between an input adapter and an output adapter are enhanced by performing two look-up operations. The first look-up operation is performed in the input adapter which receives the cell to be switched. The first look-up operation retrieve the address of the target output port and a connection control block. The second look-up operation is performed in the target output adapter and makes use of the results of the input adapter search to retrieve the information need to complete the transfer of the cell to the target output port.

Abstract: A method for balancing traffic among parallel links connecting two signalling points of a Common Channel Signalling System (SS7) when one or more of the links becomes unavailable. A change-over process causes SLS (Signalling Link Selection) field values originally associated with the unavailable link to be reassigned to remaining available links on a distributed basis. A change-back process, used where a previously unavailable link is restored to service, causes SLS field values to be reassigned from the other available links to the restored link.

Abstract: A system of high availablity synchronous bandwidth allocation comprising an FDDI segment to which are connected a first device for allocating synchronous bandwidth over the FDDI segment to any requesting device, and at least a second device for requesting synchronous bandwidth over the FDDI segment. The first device and a third device also connected to said FDDI segment, are capable of a exchanging information regarding the allocation of synchronous bandwidth to at least the second device, the third device can take over for the first device as synchronous bandwidth allocator, if the first device fails.

Abstract: The security provided by encryption of ATM cells is enhanced by testing each cell for low data content level. If a cell has a low data content, its contents are nevertheless compressed and the resulting string is used to replace the original data. A length character and a randomly generated number which are added to the freed-up byte positions in the data field of the cell. The entire, modified data field is encrypted before the cell is transmitted. At a receiving system, a compression indicator is checked to determine whether the cell contains original or compressed data. If necessary, the length field and the random number are stripped and the remaining cell data is decompressed before the cell data is decrypted.

Abstract: A method dynamically changes the bit rate or bandwidth of constant bit rate data structures in an Asynchronous Transfer Mode (ATM) communications environment. The method defines within a data channel a Change indicator (CI) indicative of an end user's request for a bit rate change within said data structures. The Change Indicator is continuously transmitted from a source side to a destination side in the ATM environment, along with the data structures on said data channel. Upon receipt at the destination side of a user's request of a bit rate change, the destination side modifies the value of said Change Indicator. The source side, acknowledges the modification of the value of the Change Indicator, whereby the transmission of data structures continues on the data channel with a new constant bit rate.

Abstract: A multinode, multicast communications network has a distributed control for the creation, administration and operational mode selection operative in each of the nodes of the network. Each node is provided with a Set Manager for controlling either creation of, administration or access to a set of users to whom a multicast is to be directed. The Set Manager maintains a record of the local membership of all users associated with the node in which the Set Manager resides. A given Set Manager for each designated set of users is assigned the task of being the Set Leader to maintain membership information about the entire set of users in the multicast group. One of the Set Managers in the communications network is designated to be the Registrar which maintains a list of all the Set Leaders in the network. The Registrar insures that there is one and only one Set Leader for each set of users, answers inquiries about the membership of the sets and directs inquiries to appropriate Set Leaders if necessary.

Abstract: In a compiler for the GDMO language, a verified and ordered output list of GDMO templates is provided by a method that lists each template in the output list such that all listed templates are preceded in the list by templates that are referenced by a listed template.

Abstract: A flow control apparatus implemented in a virtual path ATM communication system comprising a plurality of nodes interconnected by physical links which comprise virtual paths including a plurality of virtual channels. A connection between two nodes is defined as the combination of a physical link, a virtual path, and a virtual channel. Connections are shared between a reserved bandwidth service and a best effort service. ATM data cells conveyed on said best effort service are routed from node to node by analyzing their virtual connection identifier. Queues, allocated as needed from a pool of free queues, are used to store all incoming ATM data cells having the same virtual channel identifier.

Abstract: Stackable communication network repeater hub capable of performing segmentation while retaining full stack management. Each hub in a stack can control the stack so that if a hub or group of hubs is segmented, one of the hubs is automatically allocated as the master hub. The master hub supplies a synchronizing signal, interprets network commands, and provides control signals for executing the commands.

Abstract: A convolutional digital to analog converter (CDAC) according to the present invention enables to apply the convolution operation between the digital input signals and the Fourrier transform of a filtering transfer function. This convolution operation is combined with interleaved sampling performed by a clock splitter and also a multiplier generator device.

Abstract: A system and method for distributing application-to-application network communications protocol processing. Host computers implement distributed API processing across a high speed I/O channel increasing throughput. The application API conforms to standard protocols but protocol processing is distributed using a cross-channel distributed sockets API at the session layer. This API allows multiplexing of data from one or more hosts to one or more front end routers managing network communications. Multiplexing increases network performance through parallel processing and advantageously employs host high speed I/O functions. Front end routers perform lower level protocol tasks necessary to exchange data over the communications network.

Abstract: A topology manager within a data communication network including a number of nodes interconnected by bi-directional links, wherein each said node is provided with means for dynamically setting and storing within the node a full topology database including full parent-node-relationship references. The system is is capable of fast path determination and fast spanning tree recovery based on the topology database contents.