Abstract: A multi-domain network manager provides alarm correlation among a plurality of domains included in a communications network. Individual network management systems each monitor a single respective domain of the communications network, and provide intra-domain alarms indicative of status specific to the single respective domain. The multi-domain network manager receives the intra-domain alarms, and correlates them to provide inter-domain alarms as well as responses in the form of corrective actions. The multi-domain network manager thus provides a high level of correlation and response for the entire network while each network management system provides a lower level of correlation and response for an individual domain of the network.

Abstract: A content addressable memory (CAM) structure, and a method for its use, wherein data items of different selected lengths stored in the CAM may be located by matching sequences of CAM data words with sequences of input data words. Extension bits associated with each CAM data word control a sequence of comparison cycles to permit an input data item to be compared simultaneously with multiple input data items of the same length stored in the CAM structure. The CAM structure can be used without modification to store data items of various selected lengths. A begin bit associated with each CAM data word is used to mark the beginning of each stored data item and, in an exact match mode of operation, a global line is used to mark the beginning of an input data item. Match logic associated with each CAM data word generates a match till now signal in each comparison cycle, and the signal is propagated to the end of the data item if an exact match is detected.

Abstract: An apparatus and method for generating a congestion indication bit to be written to the CI field of a backwards RM ATM cell to be transmitted by a network interface utilizes a slot.sub.-- type congestion signal for indicating that the number of slots available for receiving cells is below a threshold limit, and a CI.sub.-- VC signal for indicating that the buffer space consumed by cells received on a particular VC has passed a threshold value. The CI bit in a backward RM cell for the VC when either the slot.sub.-- type congestion signal is set or the CI.sub.-- VC bit is set or the EFCI bit was set in the last data cell received by the network interface or the CI bit was set in the last forward RM cell transmitted by the network interface.

Abstract: A method of scheduling the transmission of cells from a network node involves storing entries in a schedule table at predetermined locations, wherein each location represents a point in time at which a cell is to be transmitted. Each entry in the table contains a pointer to a list of virtual circuits having cells scheduled for transmission at the time corresponding to the location of the entry in the table. When a VC has a cell to be transmitted at a particular time, the VC is queued to the head, rather than the tail, of the list of VCs pointed to by the pointer located at the entry in the table corresponding to the time at which the cell is to be transmitted. The VC is therefore the first VC transmitted from the list of VCs.

Abstract: A switch for use in a virtual communications system having multiple local area networks interconnected by multiple switches includes a first communications port connected to a network resource and a second communications port connected to other switches in the virtual communications system. A control console detects a communication from the resource to an addressee. The addressee is a member of a local area network within one or more virtual networks which exclude the network resource. The local area network is interconnected to the second communications port by another switch. The control console appends a privileged header to the communication which is detected by the other switch. Responsive to detection of the privileged header the other switch directs the communication to the local area network.

Abstract: A flow control method and apparatus for controlling flow through an output link in a communication network modifies a prior art Phantom flow control method by calculating the maximum allowable cell rate as a function of the number of active flows through the output link. To accomplish this, the method and apparatus calculates alpha smoothing parameters as a function of the number of virtual channels flowing through the output link. The method and apparatus improves the stability of the Phantom flow control method, and also enables it to be used with less costly network switches, such as shared memory switches.

Abstract: An apparatus and method for transferring data from a source memory (e.g. a host memory) to a peripheral interface via a bus utilizes a transmit buffer memory coupled to the peripheral interface, and a current time counter advancing at the rate at which data is to be transferred from the transmit buffer memory to the peripheral interface. A schedule table data structure stores entries in some or all of its locations, where each location corresponds to a point in time at which data is to be transferred from the transmit buffer memory to the peripheral interface. A schedule table pointer is used for pointing to successive locations in the schedule table. The schedule table pointer advances at a rate faster than the current time counter advances so that the schedule table pointer represents a point in time which is ahead of the point in time currently output by the current time counter.

Abstract: The rate based end system may provide feasible transmission rates for end source stations. As an extension to the rate based end to end system, there is disclosed a hybrid link by link flow control system. The link by link control system is built upon the end to end, rate based traffic control system. The link by link system utilizes bandwidth un accounted for by the end to end system. The link by link system uses feasible transmission rates obtained by the end to end system to determine the size of the buffers required for overbooking and for updating credit information to sustain the calculated rate.

Abstract: A mechanism by which interrupt frequency mitigation is combined with transmit raw cell status report frequency mitigation is presented. A tx raw cell status report is allowed to occur for only every N raw cell tx slots consumed. When the rate of interrupt requests is mitigated in accordance with holdoff parameters including a holdoff event count corresponding to X interrupt events and a holdoff time interval, and the raw cell status report counts as an interrupt event, an interrupt request is generated for an enabled interrupt if N*X events has occurred or the holdoff time interval has elapsed.

Abstract: A faceplate system that removably mounts interchangeable connector mounting inserts. The system uses a faceplate frame having mounting rails with access notches and rectangular connector mounting inserts that have corner legs and spacer walls at their ends. The legs have ledge surfaces slidingly engage the under sides of the mounting rails, and the spacer walls slidingly engage the upper sides of the mounting rails. The legs gain access to the under sides of the rails through the rail notches.

Abstract: An intermodule network bus architecture using only two bus wires to transmit data and module state information. A two-pin bus interface in each network module connected to the bus provides for a distributed arbitration procedure in the event that two or more modules are competing for bus access, and provides a coding scheme under which both data signals and collision announcements are transmitted from module to module through the two-wire bus. The architecture handles multiple distributed repeater modules, as well as other network components such as bridges and routers connected to the same bus. An important aspect of the invention is that multiple bus interfaces function as a distributed state machine, to handle the arbitration process and to provide a consistent framework for detecting and processing data signals and various types of collisions, including receive collisions detected on a single local module port, and transmit collisions involving activity on multiple local ports of one or more modules.

Abstract: A packet is originated in a unit 10 as a data field DATA 11 plus a CRC (cyclic redundancy check) check field CRC 12 by a CRC circuit 13. This packet has a header HDR (with a routing information field RIF) added to it in a unit 20, converting it into a message for transmission through a message network. A check correction field CCF is computed by unit 23 in unit 20, by looking up precomputed check subfields stored with the routing subfields (the routing information field being constructed by selecting from the stored subfields), such that the CRC field is a valid CRC check field for the complete message. At the destination, unit 30 can be the final user unit, checking the entire message and extracting the data field DATA therefrom; the DATA field does not need to be checked, as the CRC field acts as a check both for the data field DATA alone and the entire message.

Abstract: A method for connecting a first communication system with a third communications system, by passing through a second communications system, is disclosed. A first frame is received from the first communications system, where the first frame has a multicast address as a destination address. The multicast address requires the frame to be transmitted onto the second multicast address is translated into a functional address. The functional address is written into a second frame, and the second frame is transmitted onto the second communications system. A station receiving the second frame translates the functional address into a multicast address and writes the multicast address into the destination address field of a third frame, and transmits the third frame onto the third communications system.

Abstract: A cable management unit having a tray-divider/rack mount tray adapted to mate with a clamp/cable organizer. The clamp/cable organizer has a several mounting ears adapted to mate with a corresponding number of slide receipt openings in the tray-divider/rack mount tray. The tray-divider/rack mount tray includes a generally planar base, the base containing a plurality of openings to accommodate a plurality of bundling straps, two slide sections, each of the slide sections being formed as downward vertical extensions to the base and extending at a ninety degree angle from the base and each including a slide receipt opening, and two sets of mounting ears, each one of the sets formed from a corresponding slide section, each one of the sets providing attachment means to a rack.

Abstract: An interconnecting apparatus includes one or more interfaces. Each interface connects to a network. The interconnecting apparatus interconnects the networks attached to the interfaces. The device utilizes distributed autonomous forwarding engines on each interface in that each interface has a forwarding engine corresponding to it. Each forwarding engine only knows the configuration information and how to receive and transmit packets on the one interface to which it corresponds. Each forwarding engine acts independently to process packets, yet each interacts together to collectively provide packet forwarding which is protocol independent, interface independent, and scalable.

Abstract: A method for routing data cells in a computer network having a number of nodes and network resources, each node and network resource having a memory, the memories of the network resources each having routing software, storing a number of node connections in each of the memories of each of the nodes, storing a plurality of network resource connections in each of the memories of each of the network resources, selecting a first node, the first node having data cells to transmit, selecting in the first node a first node connection, transmitting the cells on the first node connection to a first network resource, receiving the cells in the first network resource, selecting in the first network resource a first network resource connection, and transmitting the cells on the first network resource connection.

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: An apparatus and method for transferring data from a source memory to a transmit buffer memory and then from the transmit buffer memory at a particular rate. A current time counter advances at the rate at which data is to be transmitted from the transmit buffer memory to the interface. A schedule memory stores entries, each valid entry being associated with data that is to be transmitted from the transmit buffer memory to the interface. A timestamp is associated with each valid entry in the schedule memory.

Abstract: A method and apparatus for monitoring data sent between a source node and destination node in a switched network, wherein the switches configure themselves to establish a connection path to a probe switch to receive the monitored data. The source and destination are identified along with the probe switch. An originating switch on a path between the source and destination is identified and connections between the originating switch and the probe switch are established. The originating switch sends out a first message and when the probe switch receives the first message, it returns a second message to the originating switch. Each switch between the originating switch and the probe switch that receives the first and second messages configures itself to establish the connection path.

Abstract: A technique for modifying the IEEE 802.3 standard for selecting backoff times in a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) network, in the event that a collision is sensed by a node that has captured the network communication channel. If there is a small number of active nodes on the network, one node may capture the channel and the standard backoff algorithm makes it increasingly unlikely for another node to transmit. The new technique provides for less aggressive, i.e. longer, backoff times before at least the first retransmission attempt made by a node that has captured the channel, and in addition provides for the use of a stopped backoff algorithm. Three specific examples of methods to choose a backoff time and two methods of using a stopped backoff algorithm are disclosed.