Abstract: Given a large number of traffic matrices, the matrices are divided into M clusters, where M is a relatively small number. A load-balancing apparatus is implemented as an application over the SDN controller. Such an application is executed to configure and reconfigure the switches to achieve near-optimal load balancing, even when the traffic load changes. For each cluster, a near-optimal explicit routing configuration is determined. The combination of explicit routing (cluster-specific) and destination-based routing (same for all clusters) is used to achieve near-optimal load balancing for each cluster.

Abstract: Given a large number of traffic matrices, the matrices are divided into M clusters, where M is a relatively small number. A load-balancing apparatus is implemented as an application over the SDN controller. Such an application is executed to configure and reconfigure the switches to achieve near-optimal load balancing, even when the traffic load changes. For each cluster, a near-optimal explicit routing configuration is determined. The combination of explicit routing (cluster-specific) and destination-based routing (same for all clusters) is used to achieve near-optimal load balancing for each cluster.

Abstract: For a survivable portion of a network, a backup port for a first router of the survivable network, to reach a destination node in the event of a single link failure, may be determined by (a) accepting a routing path graph having the destination node, wherein the routing path graph includes one or more links terminated by one or more primary ports of the first router, and (b) for each router of at least a part of the routing path graph, (1) assuming that a link terminated by a primary port of the current router is removed, defining (A) a first part of the routing path graph including the destination node, and (B) a second part of the routing path graph separated from the first part wherein the second part defines a sub-graph, and (2) determining the backup port for the first router by examining the sub-graph with respect to the first part of the routing path graph.

Abstract: Packets out-of-sequence problem can be solved by using a window flow control scheme that can dispatch traffic at the cell level, in a round robin fashion, as evenly as possible. Each VOQ at the input port has a sequence head pointer that is used to assign sequence numbers (SN) to the cells. Also a sequence tail pointer is available at each VOQ that is used to acknowledge and limit the amount of cells that can be sent to the output ports based on the window size of the scheme. Each VIQ at the output port has a sequence pointer or sequence number (SN) pointer that indicates to the VIQ which cell to wait for. Once the VIQ receives the cell that the SN pointer indicated, the output port sends an ACK packet back to the input port. By using sequence numbers and the relevant pointers, the packet out-of-sequence problem is solved.

Abstract: Packet-level multicasting may be used to avoid the cell header and the memory size problems. One or more multicast control cells may be appended before one or more data cells of a multicast packet to carry multicast bitmap information. The control cell may be stored at the cell memory. This approach is suitable for a multi-plane, multi-stage packet switch.

Abstract: Practical packet reassembly in large, multi-plane, multi-stage switches is possible by using a scheduling technique called dynamic packet interleaving. With dynamic packet interleaving scheduling, if more than one packet is contending for the same output link in a switch module, an arbiter in the switch module gives priority to a partial packet (i.e., to a packet that has had at least one cell sent to the queue). The number of reassembly queues required to ensure reassembly is dramatically reduced (e.g., to the number of paths multiplied by the number of scheduling priorities). Deadlock may be avoided by guaranteeing (e.g., reserving) at least one cell space for all partial packets.

Abstract: To use the memory space more effectively, cell memory can be shared by an input link and all output links. To prevent one flow from occupying the entire memory space, a threshold may be provided for the queue. The queue threshold may accommodate the RTT delay of the link. Queue length information about a downstream switch module may be sent to an upstream switch module via cell headers in every credit update period per link. Cell and/or credit loss may be recovered from. Increasing the credit update period reduces the cell header bandwidth but doesn't degrade performance significantly. Sending a credit per link simplifies implementation and eliminates interference between other links.