Abstract: A method for budgeted learning of link information in a network includes providing a database to contain the link information, for use by an entity connected to the network in transferring traffic over the network, and setting a maximum rate for addition of entries to the database. New entries to be added to the database are determined responsive to the traffic on the network during a learning period. The new entries are added to the database only if the addition of the entries during the learning period has not exceeded the maximum rate.

Abstract: A method for eliminating loops in a communication network in which the nodes operate as virtual bridges, having virtual ports that link the virtual bridges over virtual connections, each of the virtual connections coinciding respectively with one or more segments of the network. Respective port costs are assigned to the virtual ports responsive to a count of the network segments with which the respective virtual connections coincide, so as to favor virtual paths between pairs of the nodes that are made up of a greater number of the virtual connections, relative to the virtual paths that are made up of a lesser number of the virtual connections. Respective path costs are computed for the virtual paths, based on the port costs, and the virtual connections over which to send traffic between the virtual bridges are selected responsive to the path costs.

Abstract: A performance monitoring system for a digital network is installed in network elements having performance monitoring responsibilities. Apparatus is provided for network elements, in which a bitmap representation of performance primitives detected during an acquisition interval is used as a control in the tracking and updating of network performance parameters. Immediate access to states that enable and inhibit the evaluation of individual performance parameters is available.

Abstract: A method for processing data packets in a communication network includes establishing a path for a flow of the data packets through the communication network. At a node along the path having a plurality of aggregated ports, a port is selected from among the plurality to serve as part of the path. A label is chosen responsively to the selected port. The label is attached to the data packets in the flow at a point on the path upstream from the node. Upon receiving the data packets at the node, the data packets are switched through the selected port responsively to the label.

Abstract: A method for data communications includes receiving a time-division-multiplexed (TDM) input signal on a first circuit, the signal including an input sequence of frames of data, each such frame divided into sections for carrying respective sub-rate payloads. After determining which of the sections are active, such that the data in the sub-rate payloads of the active sections include user data, and which of the sections are inactive, the user data in the active sections are encapsulated into data packets for transmission over a packet network, while omitting from the packets at least some of the data from the inactive sections.

Abstract: A method for controlling a system of label-switched tunnels through a communication network, the method including pushing a signaling label onto a signaling frame at a first node in the network, and sending the signaling frame through the label-switched tunnels to one or more recipient nodes in the network. The signaling label is popped off the signaling frame at the one or more recipient nodes, which responsive to the signaling label, process the signaling frame so as to eliminate loops formed by the label-switched tunnels.

Abstract: A method for measuring latency in a bi-directional ring network includes transmitting a latency measurement packet from an originating node to a peer node and noting a time of receipt of the packet at the peer node. The packet is then transmitted back to the originating node in the opposite direction, while recording in the packet an indication of a peer node difference between a time of transmission of the packet from the peer node to the originating node and the time of receipt of the packet at the peer node. A time of return of the packet to the originating node is noted, so as to determine an originating node difference between a time of transmission of the packet from the originating node to the peer node and the time of return of the packet to the originating node. The latency is calculated by taking a difference between the originating node difference and the peer node difference.

Abstract: A method for producing embedded software includes providing one or more generic application handler programs, each such program comprising computer program code for performing generic application functions common to multiple types of hardware modules used in a communication system. Specific application handler code is generated to associate the generic application functions with specific functions of a device driver for at least one of the types of the hardware modules. The generic application handler programs are compiled together with the specific application handler code to produce machine-readable code to be executed by an embedded processor in the at least one of the types of the hardware modules.

Abstract: In a bidirectional ring network, in which nodes are mutually connected by network segments, a method of fault protection includes constructing a general mask indicating which of the segments can be reached. For a given data flow to be conveyed through the network from a source node to a destination node, a specific mask is constructed indicating the segments on a desired path of the flow. The general and specific masks are superimposed in order to determine a disposition of the flow.

Abstract: A communication device for interconnection of first and second networks, of which at least the first network is a bidirectional ring network, includes first and second interconnect modules, each such module adapted to receive outgoing data traffic on the first network at a data rate not substantially greater than a predetermined maximum rate for one of the ring directions, and to convey the outgoing data traffic to the second network. When a fault occurs in one of the first and second modules, the other module is reconfigured to receive substantially all of the outgoing data traffic and to convey the outgoing data traffic to the second network regardless of whether the outgoing data traffic is transmitted on the first network in the clockwise or in the counterclockwise direction.

Abstract: A method for communication via a ring network that includes a plurality of nodes. The method includes receiving at a first node in the ring network a data packet transmitted over a virtual private LAN service (VPLS), the data packet including an identification of the VPLS. The first node reads the identification from the data packet. Responsively to reading the identification, the first node forwards the data packet to at least one second node in the ring network that is associated with the VPLS.

Abstract: In a communication network that includes a plurality of nodes interconnected by links, a method for routing a data flow includes receiving a request to allocate one or more resources in the network so as to carry the data flow between first and second ones of the nodes over one of a plurality of paths therebetween, each such path including a respective sequence of the links. For the links included in each of the paths, respective levels of use of the requested resources due to communications in process over the network are determined. The path that is to carry the data flow is selected responsive to the determined levels of use of the requested resources on the links included in each of the paths.

Abstract: Communication apparatus includes a plurality of interface cards, including a central interface card and spoke interface cards, which are adapted to link communication lines to a network. A protection bus includes multiple spoke connections that link the central interface card to the spoke interface cards in a partial star configuration, such that on at least one of the spoke connections there are two of the spoke interface cards connected together to the central interface card.

Abstract: According to a disclosed embodiment of the invention, software download and installation in a ring network are synchronized in a two-stage operation in order to minimize service disruption time. In a first phase, the MPM's and UIM's in all the nodes are upgraded in parallel. Each node has two main processing modules, allowing one to be upgraded while the other continues to operate the node. In a second phase, the RIM's at the edges of a single ring segment are upgraded, one ring segment after the other, during which time each terminal node continues to operate with respect to the span connecting to its opposite side. While a span is non-operative, traffic is wrapped or diverted as necessary to maintain service of the ring. While one RIM of a node is being upgraded, the other RIM remains operational.

Abstract: A method for communication includes setting respective overbooking ratios for multiple categories of data traffic, and assigning respective bandwidth allocations to a plurality of connections for transmitting the data traffic in one or more of the categories over a network. The data traffic from the connections is coupled into respective queues, such that each of the queues is associated with one or more of the connections. Respective weights are computed for the queues responsively to the bandwidth allocations and to the overbooking ratios of the categories of the data traffic to be transmitted on the connections that are associated with each of the queues. A multiplexer multiplexes among the queues responsively to the respective weights so as to transmit the data traffic from the connections over a link in the network.

Abstract: A method for configuration of a node inserted into a bidirectional ring network includes, responsive to traffic on first and second rings of the network, determining at the node that one of the first and second rings carries the traffic in a clockwise direction around the network, while the other of the rings carries the traffic in a counterclockwise direction. The node then sends and receives advertisement packets through its network interfaces over the respective rings, advertising the determined directions of the traffic carried by the rings. Responsive to the advertisement packets received at the node, the configuration of the node is completed so that the traffic can be sent to and from the node on the first and second rings in the determined directions.

Abstract: A method for routing a data flow from a source node to a destination node among a plurality of nodes mutually linked in a ring by segments of a communication network, configured so that the data flow can traverse the ring in either of first and second, mutually-opposing directions of communication. The method includes maintaining at each of the nodes a record of respective levels of use of a network resource on the segments in the ring for both the first and second directions of communication. Responsive to the respective levels of use, one of the directions is selected at the source node, in which to route the data flow to the destination node. A notification is sent from the source node to the other nodes in the ring of an additional allocation of the resource required by the source node in order to convey the data flow to the destination node in the selected direction on the segments in the ring.

Abstract: A method for self-testing of an electronic system that includes a main module and subsidiary modules, which are connected to the main module by data lines, at least some of which may be idle. One of the idle lines is selected to serve as an aid line, and the subsidiary module to which the aid line is connected is instructed to loop back traffic reaching the subsidiary module via the aid line. Another idle line is selected for testing, and a switch in the main module is configured to link the aid line and the line under test. The subsidiary module to which the line under test is connected transmits test traffic over the idle line to the main module. If the test traffic does not return to the subsidiary module within a predetermined period of time, a failure is reported.

Abstract: A communication network includes a communication medium and a plurality of communication nodes, mutually coupled by the communication medium so as to form a ring, over which each of the nodes is configured to transmit traffic to the other nodes in both clockwise and counterclockwise directions around the ring. At least one of the nodes is configured to receive the traffic in only one of the directions at any given time.

Abstract: Routing tables of OSI layer-3 network elements are modified in order to enable entry to a RPR subnet at different entry points. This enables virtual tunnels or routing paths to utilize all existing entry links to the RPR subnet and to minimize cost factors, such as the number of RPR spans required to traverse the RPR subnet from the entry point to a destination RPR node. The routing tables of RPR subnet elements are modified, such that traffic leaving different elements but destined for the same network location outside the RPR subnet may have individualized RPR exit nodes. The respective RPR exit points for the network elements are chosen to minimize cost factors, such as the number of RPR spans required to reach the exit node from each RPR node.