Abstract: A network element includes a backplane, which includes a backplane memory holding first medium access control (MAC) address values. The network element further includes multiple tributary modules coupled to the backplane, which include network interfaces that are configured to communicate over network trunks using MAC addresses that are respectively assigned to the network interfaces. The network element further includes a common function module (CFM), which communicates with the tributary modules and the backplane memory via the backplane, and which includes a CFM memory holding second MAC address values. The CFM is arranged to assign the MAC addresses to the network interfaces by selecting the MAC addresses from among the first MAC address values when the CFM is able to access the backplane memory, and by selecting the MAC addresses from among the second MAC address values when the CFM is unable to access the backplane memory.

Abstract: A method for communication includes coupling a group of switches in a Layer-2 bridged network. The interfaces of the switches are configured so that at least one interface of at least one of the switches is configured as a first interface type, and a plurality of other interfaces are configured as a second interface type. Upon receiving frames through the interfaces of the first and second types for transmission over the network, the received frames are labeled with corresponding first and second type indications. The frames are forwarded through the Layer-2 bridged network using the switches responsively to the type indications. Frames labeled with the second type indication are permitted to be transmitted through the interfaces of the first type and prevented from being transmitted through the interfaces of the second type.

Abstract: A method for communication between first and second nodes via a communication network includes assigning multiple communication ports in two or more network nodes between the first and second nodes to serve as member ports of a multi-homing group (MHG). Each of the member ports is associated with a different, respective communication path between the first and second nodes via the communication network. A frame transmitted from the first node to the second node is accepted at the two or more network nodes. The frame has a header including header fields. A single port is selected from among the member ports by applying a hashing function to one or more of the header fields at each of the two or more network nodes. The frame is forwarded via the selected port over the respective communication path that is associated with the selected port.

Abstract: A method for establishing a connection through a communication network that includes multiple segments includes providing a sharing definition defining a sharing of bandwidth among connections in the network. Two or more candidate routes for a new connection to be established through the network are identified. For each of the two or more candidate routes, a cumulative additional bandwidth reservation to be allocated to the new connection in the segments along the candidate route is calculated responsively to the sharing definition. A preferred route having a minimum value of the cumulative additional bandwidth reservation is selected out of the two or more candidate routes. The new connection is established using the preferred route.

Abstract: A method for communication includes configuring a network node having at least first and second line cards, the line cards having respective ports, to operate as a distributed media access control (MAC) bridge in a Layer 2 network. Each of the line cards has a respective forwarding database (FDB). Upon receiving a data packet on a port of the network node from a MAC source address, the data packet is conveyed to at least the first line card for transmission to the MAC destination address. The MAC source address of the data packet is checked against the records in the FDB of the first line card. If the FDB does not contain a record of an association of the MAC source address with the port on which the data packet was received, the record is added to the FDB of the first line card, which sends a message to at least the second line card informing the second line card of the association.

Abstract: A method for data communications includes receiving a time-division-multiplexed (TDM) input signal carrying a payload comprising data and determining whether the data comprise synchronous or non-synchronous data. A first encapsulation scheme is selected if the data comprise synchronous data, and a second encapsulation scheme is selected if the data comprise non-synchronous data. The data are encapsulated for transmission over a packet-switched network in accordance with the selected encapsulation scheme.

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.

Abstract: A method for communication includes coupling a network node to one or more interface modules using a first group of first physical links arranged in parallel. Each of the one or more interface modules is coupled to a communication network using a second group of second physical links arranged in parallel. A data frame having frame attributes sent between the communication network and the network node is received. A first physical link out of the first group and a second physical link out of the second group are selected in a single computation based on at least one of the frame attributes. The data frame is sent over the selected first and second physical links. This method allows two or more link aggregation groups to be concatenated, using a single processing stage to determine port assignment for each frame in each of the link aggregation groups.

Abstract: A method for data communications includes receiving a time-division-multiplexed (TDM) input signal carrying a payload comprising data and determining whether the data comprise synchronous or non-synchronous data. A first encapsulation scheme is selected if the data comprise synchronous data, and a second encapsulation scheme is selected if the data comprise non-synchronous data. The data are encapsulated for transmission over a packet-switched network in accordance with the selected encapsulation scheme.

Abstract: A method for transporting fibre channel (FC) traffic over a packet-switched communication network includes identifying a sub-sequence of repetitive FC signals in a first sequence of FC words accepted over a FC link from a source FC device. The first sequence of FC words is translated into a second sequence of data packets in accordance with a communication protocol supported by the packet-switched communication network. The second sequence includes a repetition indication packet that identifies the sub-sequence of repetitive FC signals. The second sequence of the data packets is transported to a receiver over the packet-switched communication network using the communication protocol.

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 defining a resource-sharing group including two or more communication paths that traverse at least two different routes through a communication network, the routes traversing at least one common network element. A notification of an affiliation of the two or more communication paths with the resource-sharing group is distributed over the network. A resource associated with the at least one common network element is allocated so as to share an allocation of the resource among the communication paths in the resource-sharing group responsively to the notification.

Abstract: A method for communication includes provisioning different first and second instances of a multipoint-to-multipoint (MP-MP) communication service over respective first and second alternative sets of links (44A . . . 44D, 48A . . . 48D) that connect a plurality of endpoints (24A . . . 24C, 28) in a network (20), each of the sets traversing network nodes (32A . . . 32D), which provide physical layer resources for operating the links. The communication service is provided to the endpoints over the first set of links (44A . . . 44D) using the first instance. Upon detecting a failure in the first set of links, the physical layer resources of one or more of the links in the first set is deactivated by at least one of the network nodes, in order to cause a loss of connectivity in the first set of links. Responsively to sensing the loss of connectivity, the communication service is resumed over the second instance by automatically transferring communication among the endpoints to the second set of links (48A . . .

Abstract: A method for communication includes, in a communication network that includes multiple ring nodes arranged in at least first and second ring networks that are connected by two or more of the ring nodes serving as interconnect nodes, accepting at the two or more interconnect nodes respective copies of a data packet, which is sent from a source user node connected to the first ring network. An attribute is extracted from the respective copies of the data packet at each of the interconnect nodes, and a predefined mapping function is applied to the extracted attribute so as to select a single interconnect node for forwarding the data packet to the second ring network. A single copy of the data packet is forwarded to the second ring network only from the selected interconnect node, while refraining from forwarding other copies from the other interconnect nodes.

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 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 communication includes encapsulating multiple data packets, which carry data and have respective drop precedence (DP) values selected from a range of possible DP values, to produce a concatenated frame of a transport protocol. A composite drop precedence (CDP) value is assigned from the range to the concatenated frame using a pseudo-random assignment function that depends on a distribution of the DP values of the data packets in the concatenated frame. The concatenated frame is transported through a communication network using the transport protocol, in accordance with the pseudo-randomly assigned CDP value.

Abstract: A network node in a communication network includes a plurality of ports, at least a subset of which is grouped in a link aggregation (LAG) group. The node includes packet processing logic, which is coupled to receive data packets having respective destination addresses that specify forwarding the packets to groups of multiple recipients through at least one of the ports and to process the data packets so as to forward only a single copy of each of the data packets via the output ports in the subset, while distributing forwarded copies of the data packets among the output ports in the subset so as to balance a traffic load within the LAG group.

Abstract: A method for data communications includes linking a plurality of edge devices to communicate with a remote network device via a network in accordance with a packet-oriented Layer 2 communication protocol. At each of the plurality of edge devices, incoming data frames are received from client nodes in accordance with respective native Layer 2 protocols, at least one of which is different from the packet-oriented Layer 2 communication protocol. The received incoming data frames are converted at each of the edge devices from at least a first format specified by the native Layer 2 protocols to a second format specified by the packet-oriented Layer 2 communication protocol. The incoming data frames are transmitted in the second format via the network to the hub.

Abstract: A method for communication between first and second nodes via a communication network includes assigning multiple communication ports in two or more network nodes between the first and second nodes to serve as member ports of a multi-homing group (MHG). Each of the member ports is associated with a different, respective communication path between the first and second nodes via the communication network. A frame transmitted from the first node to the second node is accepted at the two or more network nodes. The frame has a header including header fields. A single port is selected from among the member ports by applying a hashing function to one or more of the header fields at each of the two or more network nodes. The frame is forwarded via the selected port over the respective communication path that is associated with the selected port.