Abstract: A method for changing a network characteristic or capability, such as the communication rate of network segments, software version or protocol. All nodes in the network perform the change synchronously while continuing to communicate within the existing capabilities. A new configuration is downloaded to the nodes, and a manager node exchanges validation messages with the other nodes in order to verify that the nodes can be reconfigured and will be able to complete the process successfully. The manager node then sends a command message to the other nodes to execute the change. In response, the other nodes begin substantially simultaneously to communicate in accordance with the new characteristics and/or capabilities. This method helps to minimize the duration of the upgrade process, while avoiding traffic hits and minimizing abnormal operation that may occur during the upgrade.

Abstract: A data communication network includes a plurality of primary virtual bridges, interconnected by primary virtual connections so as to transmit and receive data packets over the network to and from edge devices connected thereto. One or more backup virtual bridges, each associated with at least one of the primary virtual bridges, are connected by at least one secondary virtual connection to at least another one of the primary virtual bridges, so that upon a failure of one of the primary virtual bridges with which it is associated, the backup virtual bridge transmits and receives the data packets over the network via the at least one secondary virtual connection in place of the at least one of the primary virtual bridges.

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: A method for data broadcast over a network includes receiving at a virtual bridge a data packet to be flooded over the network, and passing the data packet from the virtual bridge to a multicast-capable router, along with a broadcast indication. Responsive to the broadcast indication, the router determines a group of destination addresses to which the packet should be multicast, and creates copies of the packet for transmission over the network to the destination addresses in the group.

Abstract: Explicit routing of network traffic over RPR rings using MPLS signaling techniques, including unnumbered links. A modified LSP_TUNNEL_INTERFACE_ID object is provided with a RPR IP address instead of the conventional LSR Router ID, and with a direction indicator in place of the conventional interface ID. A novel subobject is included in the ERO and RRO, which holds the RPR IP address of the sending node in place of the conventional router ID, and a direction indicator in place of the conventional interface ID. The network nodes inspect the directional indicator that is received in a path message or a Resv message to determine the direction in which traffic is to be sent and received in an explicit route.

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 method for handling traffic in a communication network includes setting an aggregate limit on a total rate of transmission of information by a group of flows to be transmitted over the network, and setting a respective individual limit on an individual rate of transmission by each of the flows in the group. When the information carried by packets in any given one of the flows is in excess of the respective individual limit, the packets in excess of the respective individual limit in the given one of the flows are tagged with a first excess flow tag. When the total rate of transmission of the information is in excess of the aggregate limit, the packets in excess of the aggregate limit are tagged with a second excess flow tag. Resources in the network are allocated to convey the packets responsive to the first and second excess flow tags.

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 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 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: A method for fault protection in a bidirectional ring network includes transmitting first and second flows of packets around the bidirectional ring network while defining the first flow as a wrapping flow and the second flow as a non-wrapping flow. Upon detection by a node in the network that a segment of the network proximal to the node has failed, the packets in the first flow are wrapped at the node between clockwise and counterclockwise directions on the network so as to avoid the failed segment, while the packets in the second flow are not wrapped.

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: A method and apparatus for transmitting data over a channel having a variable transmission rate. A transmitter determines the rate of transmission of the data over the channel and receives a datagram for transmission over the channel at the determined rate of transmission. The transmitter divides the datagram into fragments of a size no greater than a size limit that is set for the datagram responsive to the determined rate of transmission and transmits the fragments over the channel.

Abstract: An electronic digital signal cross-connect system (EDSX) is provided which includes a plurality of input terminals for respectively receiving bipolar 3-level input signals having a predetermined bit rate, and a plurality of output terminals for respectively providing bipolar 3-level output signals having the same predetermined bit rate. An interface circuit is provided which has an input section coupled to the input terminals to receive the bipolar 3-level input signals and an output section coupled to the output terminals to output the bipolar 3-level output signals. The input section of the interface circuit is constructed to include converting circuitry for converting the bipolar 3-level input signals into predetermined coded signals. Correspondingly, the output section of the interface circuit includes converting circuitry for decoding the predetermined coded signals into bipolar 3-level output signals.