Abstract: A method and apparatus for detecting broadcast storms in an emulated Local Area Network are provided. The broadcast rates of the nodes in the emulated Local Area Network are monitored during monitoring periods. The broadcast rate for a node is the rate at which a LAN emulation server receives broadcast messages from the node during a monitoring period. Each of the broadcast rates is compared with a maximum allowed broadcast rate. If any of the broadcast rates exceeds the maximum allowed broadcast rate, then it is determined that a broadcast storm is occurring. Once it is determined that a broadcast storm is occurring, various countermeasures can be taken. For example, a warning indication may be generated, messages from the node that is causing the broadcast storm may be ignored until the broadcast storm stops, or the node that is causing the broadcast storm may be removed from the emulated Local Area Network.

Abstract: A system for routing packets in a network environment having a connection-oriented subnetwork, a plurality of routers coupled to said connection-oriented subnetwork, and a plurality of established virtual circuits. A packet is received by a router for forwarding toward a packet destination. A best existing virtual circuit across said connection-oriented subnetwork is identified from said plurality of established virtual circuits. The best existing virtual circuit is analyzed to determine whether it is both feasible and efficient for forwarding the packet toward the packet destination. If the best existing virtual circuit is both feasible and efficient, then the packet is forwarded using the best existing virtual circuit. If the best existing virtual circuit is either not feasible or inefficient, then a new virtual circuit is established to an optimal next hop router and the packet is forwarded using the new virtual circuit.

Abstract: A method and apparatus for identifying an agent based on a decision tree is provided. The apparatus transmits a series of queries to the agent and the agent transmits responses to the queries back to the apparatus. Based on the responses, the apparatus determines the identity of the agent. The apparatus determines the series of queries by traversing the decision tree based on responses sent by the agent to previous queries. When the traversal arrives at a leaf node of the decision tree, an agent associated with the leaf node is used to identify the agent. If the traversal fails before arriving at a leaf node, then a weight is determined for each supported agent based on the responses sent by the agent, and the agent with the greatest weight is used to identify the agent.

Abstract: Apparatus for monitoring and displaying the status of a local area network. The network includes a hub with ports for connection to various data terminal equipment in a star configuration and for connection to other hubs of the network. The hubs each have different types of plug-in modules which have ports for connecting the hub to different types of network cable such as fiber optic cable, unshielded twisted pair cable and shielded twisted pair cable. Information is automatically provided to a control console identifying the types of modules and the location of the modules in the hub so that an image of the actual hub can be displayed on the screen of the control console. The actual hub image shows the location and types of modules installed in the hub. In addition, information regarding the connection of each of the hubs to other hubs of the network is obtained and provided to the control console.

Abstract: A method for minimizing advertising of metrics in a network. The described invention minimizes advertising of metrics by providing for each node to identify to the other nodes the metrics it will utilize in path selection. Each node then advertises only those metrics which are utilized by at least one other node in the network.

Abstract: An asynchronous transfer mode (ATM) network or the like employing a method and apparatus for automatically determining the topology of the network is described. The method and apparatus provides for each switch in the network transmitting on each of its ports link advertisement messages (without processing intervention by intermediate switches). The link advertisement messages are received by neighbor switches and forwarded to a topology manager. The topology manager constructs network topology profile information based on received link advertisement messages. Further, the topology manager is able to verify bidirection links based on the received link advertisement messages.

Abstract: An asynchronous transfer mode (ATM) network or the like employing a method and apparatus for automatically determining the topology of the network is described. The method and apparatus provides for each switch in the network transmitting on each of its ports link advertisement messages (without processing intervention by intermediate switches). The link advertisement messages are received by neighbor switches and forwarded to a topology manager. The topology manager constructs network topology profile information based on received link advertisement messages. Further, the topology manager is able to verify bidirection links based on the received link advertisement messages.

Abstract: An internetwork routing protocol which supports virtual networks. Routing tables are maintained in routers or gateways which identify whether or not a destination is directly reachable by the router listed in the routing information entry, or whether it is merely part of a virtual network served by the listed destination routers. For directly reachable connections, datagrams may be directly delivered to any router claiming such status with respect to the network with assurance of likely delivery to the destination. Routers in communication with a virtual network must first be queried for the identity of a particular destination router address before packets are delivered to eliminate the need of packet forwarding.

Abstract: A data communications network providing for automatic reconfiguration of a hub concentrator or the like dependent on the protocol used by a device attached to the concentrator. The concentrator includes a circuit for receiving a message packet from a device coupled with the concentrator and for determining the protocol used in the transmission. Utilization of the disclosed circuit provides for automatic reconfiguration in the event a device is moved from one port on the concentrator to another port or a new device is connected to the concentrator.

Abstract: A packet processing method and apparatus efficiently process a binary data packet based upon information contained in the header portion of the packet. The method and apparatus employ a binary tree search method for determining ranges of key elements of the packet and associating with each of the ranges a user supplied data and filter mask. The binary search process employs a unique binary tree storage structure which both conserves storage memory and enables efficient processing to reach a final node of the binary tree decision table. Nodes can be added or deleted from the table by the user as the data packet processing needs change.

Abstract: A method and apparatus for transmitting data between nodes connected to a communications bus, preferably a computer backbone, divides a full bus width into a plurality of sub-buses. Each sub-bus can be independently operated, and each node on the network can connect to one or more of the sub-buses. The apparatus provides, at a transmitting node, a determination of which sub-buses are available to transmit a data packet to one or more receiving nodes. The data words are divided into sub-words, thereby reducing the memory access time requirements and saving memory costs. In accordance with a particular embodiment, the header, at the beginning of the data packet, and the error check control, provided at the end of the data packet, are sent at a slower speed than the data information portion of the packet. The data information portion of the packet is sent at the highest speed compatible with the receiving node or nodes. In case one sub-bus fails, a node can transmit data over the other sub-buses available to it.

Abstract: A delayed replace mechanism for a streaming packet modification engine. The delayed replace mechanism allows for packet streaming where embedded fields within a data packet may be modified dependent upon fields following them within the data packet. Data to be forwarded is buffered through a data FIFO while marking fields that are to be replaced. Calculated replacement fields are stored in a replacement FIFO to be overwritten upon transmission from the packet streaming mechanism.

Abstract: A method and apparatus for preventing intrusive access to a network. The method and apparatus are implemented in a network having a star topology. Utilizing a network management module of a network concentrator as a centralized functional base, unauthorized Data Terminal Elements (DTEs) may be prevented from transmitting messages on a network. By providing a centrally located means by which a set of unique DTE addresses can be associated with a particular port on the network concentrator, valid DTE addresses can be associated with a message packet that contains the address of the transmitting DTE. If the DTE address matches those associated with the port from which it was received, the message packet is authorized. If the DTE address does not match those addresses associated with from which it was received, the message packet is unauthorized. When an unauthorized message packet is received, the port from which the frame was received, is partitioned.

Abstract: A token ring local area network concentrator which permits computers and other types of data terminal equipment to communicate with each other. The concentrator has several ports for connecting to the data terminal equipment and to other concentrators, with each port for connecting to the data terminal equipment having associated circuitry for regenerating and retiming data in the ring so as to reduce amplitude and phase distortion such as phase jitter. The associated circuitry includes a passive L/C tank circuit which is excited by the received data and which rings or resonates at a frequency which is preferably an integral multiple of the frequency or bit rate of the received data. The tank circuit functions to remove much of the phase jitter from the received data, thereby permitting a large number of data terminal equipment to be added to the ring and permitting longer lobe cable lengths, with lobe cables functioning to connect the data terminal equipment to the concentrator.

Abstract: An internetworking system for exchanging packets of information between networks, the system comprising a network interface module for connecting a network to the system, receiving packets from the network in a native packet format used by the network and converting each received native packet to a packet having a generic format common to all networks connected to the system, and converting each of the generic packets to the native packet format for transmission to the network; a communication channel for carrying the generic packets to and from the network interface module, the channel having bandwidth; a first processing module for controlling dynamic allocation and deallocation of the channel bandwidth to the network connected to the system via the network interface module; and a second processing module for receiving all of the generic packets put on the channel by the network interface module, determining a destination network interface module for each of the generic packets on the channel, determining w

Abstract: A method and apparatus for processing a data packet, for delivery to a designated location, store selective portions of the packet header in a high speed cache memory to increase processing speed and hence throughput for a packet delivery system. The apparatus and method receive the packets from a data channel source and store portions of the header in cache, and at least the remainder of each data packet is stored in a slower speed memory. A CPU accesses the stored header portion of each packet in cache for necessary protocol and destination information processing of the data packet. The header portions are then overwritten with new data and combined with the remainder of the data packet stored in slower speed memory for transmission to the next packet destination. Preferably, the address at which the remainder portions are stored in slower speed memory determine the cache addresses at which the header portion is stored in high speed cache memory.