Abstract: Technique for controlling data forwarding in a computer network are provided. The network comprises a set of nodes for forwarding data, wherein a first node is associated with a primary tree and a backup tree, wherein the primary tree defines a default path for the first node to forward data to a second node and the backup tree defines another path for the data forwarding in case of a failure of the primary tree. The basic principle of the techniques is to notify the first node of a failure of the primary tree wherein the notification is provided by the second node. The techniques are particularly beneficial for computer networks offering multipoint services, such as SPB-controlled networks, because the techniques ensure the congruency of the forward and reverse paths even when the data forwarding has been switched from the primary tree to the backup tree.

Abstract: A method of measuring loss in a multicast transmission in a network is described. Service frames including a service multicast destination address are sent from a source node towards a receiving node. A counter of the number of service frames sent is maintained at the source node. This counter is periodically read, and its value copied into a loss measurement OAM frame. The loss measurement OAM frame includes a unique identifier and an OAM destination address which is different to the service multicast destination address, and is sent from the source node towards the receiving node. Every time the sent frames counter is read, a measurement indicator frame is also sent from the source node towards the receiving node. The measurement indicator frame includes the unique identifier so that it can be related to the loss measurement OAM frame. The measurement indicator frame also includes the service multicast destination address, although the measurement indicator frame is distinguishable from the service frames.

Abstract: A method is executed by a network device for implementing conversation-sensitive collection for frames received on a port of a link of a link aggregation group. The network device executes an aggregator to collect the frames for aggregator clients, where each frame is associated with a service identifier and a conversation identifier. The service identifier identifies a data flow at a link level for a service. The conversation identifier identifies the data flow at a link aggregation group level, where each conversation data flow consists of an ordered sequence of frames, and where the conversation-sensitive collection maintains the ordered sequence by discarding frames of conversations not allocated to the port.

Abstract: A method of updating conversation allocation in link aggregation is disclosed. The method starts with verifying that an implementation of a conversation-sensitive link aggregation control protocol (LACP) is operational at a network device of a network for an aggregation port. Then it is determined that operations through enhanced link aggregation control protocol data units (LACPDUs) are possible. The enhanced LACPDUs can be used for updating conversation allocation information, and the determination is based at least partially on a compatibility check between a first set of operational parameters of the network device and a second set of operational parameters of a partner network device. Then a conversation allocation state of an aggregation port of the link aggregation group is updated based on a determination that the conversation allocation state is incorrect, where the conversation allocation state indicates a list of conversations transmitting through the aggregation port.

Abstract: A registration protocol for setting up and updating a tree that defines the active topology in an Ethernet network includes a plurality of application components and a plurality of attribute declaration components corresponding to the application components, wherein the application components declare and register attribute values and the corresponding attribute declaration components make and withdraw registration of the attributes.

Abstract: There is disclosed a method and apparatus for facilitating a network, such as an Ethernet LAN, for efficient forwarding of data traffic by collecting neighbor information, generating and distributing link state advertisements, populating a topology database for the network, and calculating trees for each bridge serving as a root bridge. In a preferred embodiment the method and system also prepare one or more backup topologies, and store them for use if they are needed due to a failure condition detected in the network. In a particularly preferred embodiment, probabilities are assigned to various potential failure conditions, and the probability values are used to decide which backup topologies to calculate, store, or use.

Abstract: A method and network for determining an interconnect node for establishing a forwarding path for service based data within a network system. The method includes assigning, interconnect node status information to network interconnect nodes, wherein a network interconnect node to which a passive status is assigned is only allowed to transmit service based data between an external link and another interconnect node of the network, or between two other interconnect nodes of the network. Only a network interconnect node with active status is allowed to send or receive service based data to or from the network. The method includes determining, for a given service, an interconnect node with active status for establishment of a forwarding path including the interconnect node with active status and an external link, wherein the determination is based on the respective status information assigned to the network interconnect nodes for the service.

Abstract: A method forward Ethernet frames at a node in a network supporting an implementation of shortest path bridging (SPB) protocol is disclosed. The method starts with a shortest path computation for the node (referred to as the computing node). The shortest path computation selects at least a shortest path to each destination node in the network, where a neighboring node on the shortest path to reach each node is recorded. Then it computes a downstream loop-free alternate (LFA) node for a destination node, where the LFA node is downstream of the computing node but not on the selected shortest path to the destination node from the computing node. Then when connectivity to the neighboring node on the computed shortest path is detected to be abnormal, the node forwards an Ethernet frame with a destination media access control (MAC) address corresponding to the destination node through the LFA node.

Abstract: A loop prevention method in a network node of a network having a plurality of network nodes controlled by a link-state protocol, comprising: receiving a message at a network interface which contains information on a new topology of the network; blocking forwarding of traffic to each neighbor node of the network at the network interface by a processing unit; agreeing by the processing unit on the new topology with each neighbor node; and, unblocking the forwarding of traffic when the neighbor node has information about the topology which is the same as the information about the topology stored in a memory; wherein the agreeing step includes the step of agreeing with the neighbor node on a digest of at least a portion of the topology stored in the memory.

Abstract: Silicon wafers and the like are cleaned using new scrubber-type apparatus in which measures are taken to compensate for differential cleaning of the central region of the wafer by: using rotary brushes having one or more non-contact portions arranged in the section thereof that faces the central region of the substrate, or toggling the relative position of the wafer and the rotary brushes, or directing cleaning fluid(s) preferentially towards the central region of the wafer. Another aspect of the invention provides scrubber-type cleaning apparatus in which the rotary brushes are replaced by rollers (110). A web of cleaning material (116) is interposed between each roller and the substrate. Various different webs of cleaning material may be used, e.g. a length of tissue, a continuous loop of cleaning material whose surface is reconditioned on each cleaning pass, adhesive material provided on a carrier tape, etc.

Abstract: A flow classification process is used at the edge of the shortest path bridging network to determine a flow label for attachment to a client frame entering the network. Any of several flow labels can be assigned to a client frame traversing the network to a particular egress node, and the flow labels are used by forwarding nodes to select among multiple equal-cost paths. In several embodiments, the flow label is calculated as a function of the client frame contents, which provide an entropy source for randomizing the selection of the flow label. This entropy source comprises the Internet Protocol (IP) header in the client frame, in some embodiments, but may comprise other client frame content in other cases.

Abstract: A system (300), a network management system (306), and a method are described herein for avoiding a count-to-infinity problem in a network (304) (e.g., Provider Backbone Bridging) with bridges having network interface ports (2,4) (e,g., Layer Two Gateway Ports) which are connected to an external network (302) (e.g., External Network to Network interface).

Abstract: A flow classification process is used at the edge of the shortest path bridging network to determine a flow label for attachment to a client frame entering the network. Any of several flow labels can be assigned to a client frame traversing the network to a particular egress node, and the flow labels are used by forwarding nodes to select among multiple equal-cost paths. In several embodiments, the flow label is calculated as a function of the client frame contents, which provide an entropy source for randomizing the selection of the flow label. This entropy source comprises the Internet Protocol (IP) header in the client frame, in some embodiments, but may comprise other client frame content in other cases.

Abstract: The present disclosure provides a technique for ensuring that a service or conversation is carried in a congruent manner on a Link Aggregation Group (LAG). The Service ID (e.g., conversation ID) to link mapping is configured on both sides of the LAG independently of each other. The Service ID to link assignment is stored in a well-defined format, e.g. in an assignment table. A digest is then prepared on the assignment table. The digest is exchanged between the two sides of the LAG. If there is a mismatch between the digests, then the service is transmitted on a predefined and agreed-upon default link if congruency has to be enforced for that particular service. Furthermore, the digest exchange allows verification on the configuration to check whether all services to be handed-off are configured on both sides.

Abstract: An upgraded edge node (e.g., enhanced PBB edge node, enhanced IP/MPLS edge node) and a method are described herein for providing a VLAN service for a customer in a metro network. In addition, a metro network is described herein which includes the upgraded edge nodes, traditional PB edge nodes, and a PB domain that has PB core nodes located therein.

Abstract: A method and apparatus for flushing port tables in an Ethernet network that includes a Root Bridge node (1) and a plurality of bridge nodes (2-7). A ring of bridge nodes affected by a change in the topology of the Ethernet network is identified from the plurality of, bridge nodes. The ring of bridge nodes (2-7) includes a branching bridge node (2) providing a connection to the Root Bridge node (1). Port tables are flushed only at the bridge nodes on the ring (2-7), rather than all of the bridge nodes in the Ethernet network, which greatly reduces the amount of signalling required during a relearning process.

Abstract: A network node of a telecommunications network controlled by a link-state protocol includes a network interface which receives a message that contains information on a change in topology of the network. The node includes a processing unit that blocks forwarding of traffic to at least one neighbor node of the network at the network interface, agrees on the change in topology with the neighbor node; and unblocks the forwarding of traffic when the neighbor node has information about the topology which is the same as the information about the topology in a memory. A transient loop prevention method of a network node of a network having a plurality of a network nodes controlled by a link-state protocol includes the steps of receiving a message at a network interface which contains information on a change in topology of the network. There is the step of blocking forwarding of traffic to each neighbor node of the network at the network interface by a processing unit.

Abstract: A method and arrangement for failure handling in a tree-structured communications network having interconnected edge nodes and switching nodes. VLANs may be established by using spanning trees to provide connectivity in case of a failure in the network. Emitters in the edge nodes periodically broadcast alive messages on the VLANs, and notifiers note the alive messages. A missing alive message indicates a failure on one of the VLANs, and the notifier broadcasts corresponding failure messages on the VLANs. When the alive messages are restored, the notifier broadcasts corresponding repair messages. If a notifier fails to note a failure, one of the edge nodes performs a similar function although somewhat slower.

Abstract: The present disclosure relates to a technique for forwarding frames received by a network interconnect node (114) of an internal network (112) having the network interconnect node (114), one or more internal network nodes (118, 120) and one or more other internal network interconnect nodes (116), the network interconnect node (114) having a network interconnect interface for communicating with an external network interconnect node (104) of an external network (102) and a network interface for communicating with one or more of the other internal network interconnect nodes (116) and with one or more of the internal network nodes (118, 120), wherein the frames are related to a service provided by at least one of the external network (102) and the internal network (112).

Abstract: Methods and apparatus are disclosed for applying multiple Link Aggregation Group (LAG) entities on the same set of physical links, thus making bundling of individual services or conversations possible by the different LAG entities within Link Aggregation. Each LAG entity is configured such that a single physical link is Active and all the other links are Standby. Each LAG entity may be regarded as a “bundle.” Thus the services/conversations are bundled into a LAG entity and are handed-off on the Active link during normal operation. If service hand-off is not possible on the Active link (e.g., due to a failure), then the LAG entity switches over to a Standby link thus the service/conversation is handed-off on that formerly Standby link. Bundling may simplify operations of control and signaling.