Abstract: A network management system includes a user interface, a virtual network and a device communication manager. The virtual network includes models which represent network entities and model relations which represent relations between network entities. Each model includes network data relating to a corresponding network entity and one or more inference handlers for processing the network data to provide user information. The system can poll or communicate with certain network entities and can infer the status of network connectors and other network entities for which polling is impossible or impractical. The system performs a fault isolation technique wherein the fault status of a network device is suppressed when it is determined that the device is not defective. User displays include hierarchical location views and topological views of the network configuration.

Abstract: An apparatus and method for allocating the performance of applications in a networking chassis among one or more modules in the chassis. In particular, the system acts as a chassis agent for performing network management functions. The agent performs a discovery function whereby each module discovers the location and current utilization of resources and applications for itself and transmits that information to other modules, and wherein each module maintains a slot table of such information for all modules. Based on the information in the slot table, each module performs an election function for allocating applications among the various modules in the chassis. The agent uses MIBs to gather information about the chassis and to effect control on the chassis, wherein each managed object is registered both locally and remotely in a MIB tree maintained on each module, and the data is maintained locally on the module on which the managed object resides.

Abstract: A system for interconnecting line cards attached to a networking hub is disclosed. The disclosed system operates by forming backplane networks between the line cards using shared data path resources within the hub. Each line card attached with the hub describes its hub internal networking characteristics and capabilities. A hub management agent obtains the specific capabilities and characteristics of each line card attached to the networking hub, from each of the line cards. The characteristics and capabilities of each line card include which of the shared data path resources are accessible to the line card, and how the line card is able to operate on those accessible shared data path resources. The capabilities and characteristics of the line cards are obtained by the management agent requesting each line card for the information. The request is initiated by a triggering event, for example power-up of the networking hub or attachment of a new line card to the networking hub.

Abstract: A time division multiple access protocol that prevents data collisions and that maximizes bandwidth utilization in a long distance communications network by performing implicit ranging and dynamic assignment of time slots. The propagation delay that would result when data travels from an end station to the hub is determined using an implicit ranging method. Time slots in a synchronization signal are assigned to end stations based upon the requests from end stations and the availability of time slots. Each end station is notified of its assigned time slot(s) and propagation delay and is provided with a timing signal which is the synchronization signal delayed by its propagation delay. Each end station then starts to transmit its data at the beginning of a time duration that is twice its propagation delay before the start of its assigned time slot(s) in its timing signal. Each end station transmits its data for the duration of its assigned time slot(s).

Abstract: An apparatus for forwarding a data packet from a first link to a second link is disclosed. The apparatus is coupled with a plurality of computer networks through ports on the apparatus. The apparatus maintains a spanning tree list indicating which of the apparatus ports are active. The apparatus receives a packet, and determines if the packet was received from a port that is active. If the packet was received from a port that is not active, the packet is discarded. If the packet is not discarded, the data link source address of the packet is stored in a database within the apparatus for the computer network coupled with the port from which the packet was received. The apparatus then decides, responsive to a contents of a data link destination address field in the packet, whether to forward the packet as a bridge or to forward the packet as a router.

Abstract: A network is monitored for reports indicative of a connection state among ports of a communications network. Certain ports are designated as being in a transition, and a transition table is created for each transition. The transition table includes locations that directly relate the connectivity of a first port with respect to a second port, as well as locations that relate the connectivity of other ports. The contents of the transition table are evaluated to determine the likely configuration of the communications network. State machines may be used to resolve conflicting data within the transition table, by providing a likely connection output based upon different entries within the transition table. A voting scheme is used to evaluate the outputs of the state machines and update the transition table when appropriate, and the updated transition table may also be evaluated.

Abstract: Apparatus and method for establishing "virtual connections" through a packet switched data communications network, the network including a plurality of end systems and switches connected by links. Each end system has a unique physical layer address and each switch has a connection database of valid connections between different ports on the switch and a switching mechanism for establishing temporary connections. Each switch is registered with a connection server such that, prior to transmission of a connectionless datagram from a first end system to a second end system, a path of valid connections through one or more switches from the first end system to the second end system is determined by configuring the connection table of each switch on the path with a connection identifier identified by the physical layer addresses of the first and second end systems, and wherein the data packet remains as a connectionless datagram.

Abstract: Apparatus and method for receiving alarms from multiple network management servers and applying a plurality of policy-based filters to the alarms. The filters may be named and stored in a database, and application of the policy-based filters may be scheduled for different times. The same policy-based filters may be applied to one or more multiple network management applications. The invention allows greater control over which alarms get reported to network management applications and provides a means to ensure consistency of reported alarms across multiple network management applications.

Abstract: Method and apparatus for providing a call-tapping point in a switched network with point-to-multipoint functionality. The tapping point is added as an additional destination for data being sent from a source node to a first destination node. The tapping point is also added as a destination for data being sent from the first destination node to the source node. A merge operation is performed for finding and combining common segments of the paths between the source and destination, the source and tapping point, and the destination and tapping point.

Abstract: A system provides representations of connections or other relationships among entities that make up a communications network. The representations may each have a color or shading to represent different conditions of the relationship. The representations may be graphical and may also include textual information as well as graphical hot-spots selectable by a user to provide even more detailed information regarding the relationship. The condition of each relationship may be determined based upon a combination of the conditions of the interface elements which are coupled together to form the communications relationship.

Abstract: Apparatus and method wherein multiple router interfaces are assigned the same IP network address, creating an IP work group. This enhances host mobility by allowing, in one embodiment, a host to be relocated anywhere in the work group without requiring reconfiguration of the host. As a further option, host address ranges may be specified (i.e., locked) to designated interfaces of the work group, to enhance security by restricting the allowed host mobility within the work group. An additional advantage is a reduced consumption of network and subnet addresses, because now a single address is used for several physical networks.

Abstract: Data compression and decompression are performed on a series of data points, by expressing a plurality of data points as an equation or a series of equations. Variable accuracies, and accordingly variable compression ratios, may be provided. Multiple versions of the compressed data, with corresponding multiple accuracy levels, and resulting multiple decompressions may be displayed for comparison. The method and apparatus may be used for storing network statistical data.

Abstract: According to several aspects of the present invention, a network is monitored for status information indicative of the status of a manageable device within the network. A network manager receives the status information, and updates or initializes a device model in accordance with the status information. A state machine may be used to determine a new state for the device model, and to enable or disable the device model. The network manager may also take action to inquire as to the status of the manageable device, for example by polling the manageable device or by initiating a discovery process. The device model may be used by the network manager as a basis by which to control the manageable device, and thus control aspects of the communications within the network.

Abstract: An apparatus and method for determining the topology of a computer network including data-relay devices and node devices, based on a comparison of source adddresses heard by the various data relay-devices. A source address table is compiled for each port of each data-relay device, and for each select pair of ports the addresses in the source tables are compared to determined whether there is an intersection of heard devices. In order to account for directed transmissions which are not heard at every port, further comparison is made of all of the other ports of the device, eliminating the ports for which the intersection is the empty set. From the determined connections, a topology of the network is graphed showing direct and transitive connections. In cases where there is both a direct and transitive connection, the redundant direct connection is eliminated.

Abstract: Traffic on a communications network is evaluated based on intra-subnet and inter-subnet traffic volumes. Values indicative of such volumes and of the overall network balance are displayed, along with alternative node topologies which may be evaluated and displayed. The overall network performance is based on equalizing intra-subnet traffic volume and minimizing inter-subnet traffic volume.

Abstract: Apparatus and method for receiving alarms from multiple network management servers and applying a plurality of policy-based filters to the alarms. The filters may be named and stored in a database, and application of the policy-based filters may be scheduled for different times. The same policy-based filters may be applied to one or more multiple network management applications. The invention allows greater control over which alarms get reported to network management applications and provides a means to ensure consistency of reported alarms across multiple network management applications. A telephonic alarm notification method and apparatus incorporates the policy-based filters and the capability to process alarms from multiple network segment servers so that users can be accurately notified of critical alarms generated in large and complex communications networks, via a public communications system.

Abstract: The apparatus includes a network monitor coupled to the communications network and providing numeric data representative of at least one operating parameter of the communications network. A fuzzifier module is coupled to the network monitor and converts the numeric data into fuzzy input data. A fuzzy inference engine is coupled to the fuzzifier module and processes the fuzzy input data according to at least one fuzzy rule to provide fuzzy output data representative of control actions to effect a desired state of the communications network. A defuzzifier module is coupled to the fuzzy inference engine and converts the fuzzy output data into numeric data which may be then used by a network controller to control at least one network parameter in response to the output data. The apparatus may also include a user interface and a display to allow the fuzzy input data, and the fuzzy output data to be displayed to a user.

Abstract: Method and apparatus for establishing restricted broadcast groups in a switched network. The method assigns different virtual LAN identifiers (VLAN-IDs) to different subsets of associated end systems or access ports. Tables are maintained for mapping the VLAN-IDs with associated end systems and access ports. When a broadcast packet is received at a first switch, it is encapsulated with a VLAN header, including the VLAN-IDs, and sent out a multicast channel to all other switches in the network (domain). The original packet is sent out the other access ports of the receiving switch for the designated VLAN-IDs. The switches receiving the VLAN packet remove the header and send the original packet out access ports associated with the VLAN-IDs extracted from the header. The method provides a mechanism for forwarding broadcast packets of a protocol not supported by the switching mechanism, as well as multicast packets and unicast packets from undiscovered end systems.

Abstract: Method and apparatus for determining a communications path between a source and a destination in an Internet Protocol (IP) network. The method determines a path list of next-hop routers between the source and destination by selecting between a Simple Network Management Protocol (SNMP) query of a current router on the path, and by sending a User Datagram Protocol (UDP) probe packet having a destination field with a destination IP address and a Time-to-Live (TTL) field with a value of one greater than the number of hops to the current router. The steps are iterated until the next router is determined to be the destination. Preferably, the UDP probe packets are loose-source routed through the source. In addition, a topology information database may be accessed to resolve an unknown router, and/or resolve intrarouter devices on the path.

Abstract: An improved method and apparatus of resolving faults in a communications network. The preferred system uses a trouble ticket data structure to describe communications network faults. Completed trouble tickets are stored in a library and when an outstanding trouble ticket is received, the system uses at least one determinator to correlate the outstanding communications network fault to data fields in the set of data fields of the trouble ticket data structure to determine which completed trouble tickets in the library are relevant to the outstanding communications network fault. The system retrieves a set of completed trouble tickets from the library that are similar to the outstanding trouble ticket and uses at least a portion of the resolution from at least one completed trouble ticket to provide a resolution of the outstanding trouble ticket.