Abstract: A VXI product plug-in is provided herein that is capable of higher component density. The plug-in is configured to occupy two standard size slots of a standard VXI chassis, and includes two sets of three horizontally stacked modules in upper and lower sub-compartments of a front compartment of the plug-in carrier. The six modules have the capability of being populated with 480 switching relays, which provides for a 50 percent increase in the number of switches over the prior art plug-ins. The plug-in carrier includes a rear compartment that houses a VXI bus interfacing circuit, including a mezzanine board, a bridge board, and optionally a controller board, for interfacing the switch modules with a VXI backplane bus. The Plug-in further includes an internal backplane situated within the carrier between the front and rear compartments that provides an interface between the modules and the VXI bus interfacing circuit, and specifically, include a bus that can selectively couple modules together.

Abstract: Disclosed is a chassis comprising an enclosure, a power supply assembly mounted in the enclosure and a backplane assembly mounted in the enclosure in abutting relationship with the power supply assembly; the backplane assembly having a plurality component connectors mounted thereon and a plurality of stand-off posts protruding therefrom, each of the stand-off posts including a first aperture and being electrically coupled to one of the component connectors; the power supply including a panel with a plurality of electrical contacts disposed thereon, each of the electrical contacts having a second aperture; and a plurality of screws disposed through the first and second apertures for securing the electrical contacts of the power supply to the stand-off posts of the backplane assembly.

Abstract: A FIR digital filter comprises a plurality of cascaded subfilters all operable at the same sampling rate. At least one of the subfilters has a z-transform transfer function defined by a partially factorized, n.sup.th -order polynomial in z.sup.-1, where n>2 whose co-efficients are quantized. A process for deriving the z-transform transfer function of the filter is described.

Abstract: Disclosed is a frame processing engine for receiving and processing a data frame having a header and a payload, comprising a first memory for receiving at least a portion of the header of the data frame; a second memory for receiving the payload of the data frame; and a controller, upon receipt of the data frame, for storing the header (at least most of it) in the first memory and the remainder of the data frame (including the payload) in the second memory, with the first memory having a shorter access time than the second memory.

Abstract: Disclosed is a Digital Service Unit (DSU) which, in response to a digital signal from a Digital Data System (DDS) network, uses different techniques for different possible DDS services (include DDS-SC, CC64, and basic DDS services) to determine the type of DDS service providing the digital signal services and the line rates for such services. With respect to DDS-SC service, the DSU utilizes the fact that this DDS-SC service provides network defined frames of data to which the DSU tries establish frame synchronization at different line rates. The DSU also resolves the fact the DDS-SC service and CC64 service have the same 72 KBPS line rate by detecting the presence or absence of a control bit. For Basic DDS service, the DSU monitors the received signal for a plurality of possible invalid conditions. For each line rate, an error counter for that line rate is incremented each time an invalid condition is detected.

Abstract: An Expert System 10 for providing diagnostics to a data communications network 5. Alarms from a Network Manager 24 are received and queued by an Event Manager 117 and then filtered by an Alarm Filter 118 to remove redundant alarms. Alarms which are ready for processing are then posted to a queue referred to as a Bulletin Board 120. A Controller 112 determines which one of the posted goals has the highest priority by considering a priority number associated with the goal plus a time of arrival of the goal. An Inference Engine 122 uses information from an Expert Information Structure 111 to solve the highest priority goal by a process called instantiation.

Abstract: An Expert System 10 for providing diagnostics to a data communications network 5. Alarms from a Network Manager 24 are received and queued by an Event Manager 117 and then filtered by an Alarm Filter 118 to remove redundant alarms. Alarms which are ready for processing are then posted to a queue referred to as a Bulletin Board 120. A Controller 112 determines which one of the posted goals has the highest priority by considering a priority number associated with the goal plus a time of arrival of the goal. An Inference Engine 122 uses information from an Expert Information Structure 111 to solve the highest priority goal by a process called instantiation. The process of solving the goal may be interrupted by a pause or suspension in order to perform tests under the direction of a Network Test Manager 124 or retrieve other information during which time other goals may be processed.

Abstract: A technique for dynamically translating network management primitives into operations on management information stored within a relational database hosting a management information base. A CMIP network management operation and argument is retrieved from a network management processing machine and processed by a full or partial OSI stack. The CMIP operation is examined to ascertain a type of network management operation. If the operation is of a type which interacts with the database, a database query is generated in accordance with the operation type, to perform the network management operation on the relational database.

Abstract: An Expert System for providing diagnostics to a data communications network. Expert information is entered using a user friendly User Interface which reduces need for the participation of a Knowledge Engineer. The User Interface including a template for entering a plurality of attributes for a hypothesis tree node. Among the attributes are an identifier for identifying a second node connected to the hypothesis tree node by a branch of a hypothesis tree. If the second node has not been defined, it is added to and displayed in a list of undefined nodes. Once all attributes for a template are completed, an identifier for the hypothesis tree node is added to and displayed in a list of defined nodes.

Abstract: A translator for translating objects defined in an object-oriented programming environment to a relational database schema permits persistent storage of object instances as records in a relational database. Object instances are mapped to entity tables with object instances represented by entity records. Simple attributes are mapped to primitive typed attribute columns and class valued attributes are represented by foreign keys into entity attribute tables. Derived attributes are represented by joins of the parent and child entity records.

Abstract: A translator for translating objects defined in Abstract Syntax Notation such as ASN.1 to a relational database schema permits persistent storage of object instances as records in a relational database. Object classes are mapped to entity tables with object instances represented by entity records. Simple attributes are mapped to primitive typed attribute columns and package or group attributes are mapped to separate dependent entity tables. Derived attributes are represented by joins of the parent and child entity records.

Abstract: A data modem is provided with a boot ROM having a set of instructions for a programmable processor to perform its basic functions within the modem. Enhancements and firmware updates are downloaded over a telephone line through the modem's inherent communications abilities and stored in a battery backed RAM. This permits firmware updates and enhancements to be implemented remotely without need for replacement of ROM or opening of the modem housing.

Abstract: A dialed telephone connection can be implemented as an end-to-end digital connection by virtue of switched voice transmission facilities becoming more prevalent. If such a connection is detected, it is possible to transmit digital data over the connection at a much higher rate than using analog technology. A dialed voice call is emulated to set up such a connection and the connection is then tested to determine if it is end-to-end digital. If so, high speed digital data can be passed. If not, the connection is broken and then reestablished repeatedly until such a digital connection is found. In one embodiment, the calls are alternately initiated from each of the two parties involved in attempts to increase the likelihood of achieving an end-to-end digital connection. If no such connection can be obtained after a reasonable number of tries, an analog communication session can be established.

Abstract: A switched digital circuit is used to restore a failed dedicated digital circuit to a remote station in conjunction with reconfiguration of the network's multipoint junction units (MJU). A circuit is established over the public switched digital network from the customer's central location to a remote station requiring restoral. The remote station is then connected back to the dedicated multipoint circuit, at the telephone company central office facilities, by way of digital cross connects and MJUs that perform the digital bridging. The switched digital access line, from the customer central location to the telephone company facilities is then available for use in establishing switched connections to the other remote stations. The process is sequentially repeated for each dedicated digital circuit to a remote station to be restored, thus conserving hardware required at the customer premises and minimizing the number of dial up switched digital access lines needed at the customers central location.

Abstract: The present invention is directed toward a method and apparatus in a communications device for mapping a selected group of data bits into a predetermined number of two-dimensional symbols selected from a minimized alphabet of M two-dimensional symbols forming a symbol constellation, with one of the two-dimensional symbols being transmitter during each symbol (i.e., baud) interval. A plurality of symbol mappers in an adaptive communications device use a superframe of bits per baud. Each superframe includes at least two groups of frames, a low bit frame and a high bit frame. The superframe has A) one of these two types of frames uses whole bits per baud and the other uses fractional bits per baud or B) both of these two types of frames will use fractional bits per baud.

Abstract: In a data communication network, a method and apparatus for determining routing in a diagnostic channel utilizes a search token which is passed through nodes of a memory model of the network. The memory model represents nodes as one (or a combination of) object models representing aggregation, deaggregation, mesh or translation operations. By referring to a relational database, selective searches are performed without need to flood the network with search tokens. The search results may be displayed graphically for easier understanding. The method also has general application to a relational database management system by allowing for display of the database relationships and interconnections in a graphical manner for easier interpretation by the user.

Abstract: A method and apparatus for providing for arbitrary definintion of groups in a data communication network management system. Groups are added, modified, merged, deleted or displayed as desired by the user so that all members of the arbitrarily defined group can be addressed as a group, for example to do a self test and report results. Collectives can be defined as members of the group and the collectives can be unpacked at the time of issuance of a command rather than at the time of creation of the group so that changes to the collective are reflected as changes to the group automatically. Provision is made for creating groups which are commonly desired and significant group configuration activity is logged to either a printer or a file.

Abstract: The present invention is directed toward a method and apparatus in a communications device for mapping a selected group of data bits into a predetermined number of two-dimensional symbols selected from a minimized alphabet of M two-dimensional symbols forming a symbol constellation, with one of the two-dimensional symbols being transmitter during each symbol (i.e., baud) interval. A plurality of symbol mappers in an adaptive communications device use a superframe of bits per baud. Each superframe includes at least two groups of frames, a low bit frame and a high bit frame. The superframe has A) one of these two types of frames uses whole bits per baud and the other uses fractional bits per baud or B) both of these two types of frames will use fractional bits per baud.

Abstract: An apparatus for managing transfer of a packet of information to one of a plurality of ports with each the port having an associated port speed includes a double linked list transmit queue and a plurality of port queues corresponding to the plurality of ports. The packet is read to determine a priority and destination port of the packet. A loadsheding value correlating to the packet's destination port and priority is determined and compared with a measure of the amount of free space in the transmit queue. The packet is loaded into the transmit queue if the loadsheding value is less than or equal to the measure of the amount of free space in the transmit queue. The packet is discarded in the event the loadsheding value is greater than the measure of the amount of free space in the transmit queue.

Abstract: An Expert System 10 for providing diagnostics to a data communications network 5. Alarms from a Network Manager 24 are received and queued by an Event Manager 117 and then filtered by an Alarm Filter 118 to remove redundant alarms. Alarms which are ready for processing are then posted to a queue referred to as a Bulletin Board 120. A Controller 112 determines which one of the posted goals has the highest priority by considering a priority number associated with the goal plus a time of arrival of the goal. An Inference Engine 122 uses information from an Expert Information Structure 111 to solve the highest priority goal by a process called instantiation. The process of solving the goal may be interrupted by a pause or suspension in order to perform tests under the direction of a Network Test Manager 124 or retrieve other information during which time other goals may be processed.