According to the present invention, a network device includes a plurality of ports, a communication controller that controls communication on the each port, and a communication shutoff unit that shuts off communication on any of the ports. The communication controller includes a linkup detection unit that detects a linkup of the each port, a loop detection frame sending unit that sends a loop detection frame from a linkup detected port, which is a port for which the linkup is detected after a predetermined period from a time point when the linkup is detected by the linkup detection unit, and a loop detection frame detection unit that detects the loop detection frame if the loop detection frame is received on the each port. The communication shutoff unit shuts off communication carried out on a sending port which is a port from which the detected loop detection frame is sent.

A BGP route identification method and apparatus are provided. A network device obtains a BGP route. The BGP route includes an autonomous system path attribute AS_PATH attribute, the AS_PATH attribute includes a first autonomous system number AS number, an AS number corresponding to an autonomous system that the network device is located in or manages is a second AS number, and the first AS number is equal to the second AS number. The network device determines, based on the first AS number and the second AS number, whether the BGP route is abnormal.

The disclosure describes techniques for enhancements to the Multicast Source Discovery Protocol (MSDP) to reduce Source Active (SA) message loops in one or more multicast domains having overlapping MSDP mesh groups. In some examples, a method includes receiving, by a first MSDP speaker, from a second MSDP speaker, a SA message. The method also includes, when the second MSDP speaker is in a mesh group with the first MSDP speaker, determining whether the first MSDP speaker includes an active SA state corresponding to the SA message. Additionally, the method includes, when the first MSDP speaker does not include the active SA state corresponding to the SA message, accepting the SA message and forwarding the SA message to a third MSDP speaker that is not in the mesh group with the first MSDP speaker and the second MSDP speaker.

Techniques for loop prevention while allowing multipath in a virtual L2 network are described. In an example, a NIC supports the virtual L2 network. The NIC is configured to receive, via a first port of the NIC, an L2 frame that includes a source MAC address and a destination MAC address. Based on a loop prevention rule, the NIC transmits the L2 frame via its ports except the first port. In an additional example, the NIC is further configured to send an L2 frame to a host via the first port of the NIC. The L2 frame can be a BPDU. Upon receiving a BPDU from the host via the first port, the NIC determines that the BPDU is looped back and disables the first port.

Systems and methods for supporting inter subnet control plane protocol for consistent multicast membership and connectivity across multiple subnets in a high performance computing environment. In accordance with an embodiment, by associating a multicast group with an inter-subnet partition, and enforcing a dedicated router port for the multicast group, multicast loop avoidance can be provided for between connected subnets. Because only a single router port is selected as being capable of handling the MC packet, no other router port in the subnet can then pass a multicast packet back to the originating subnet.

A router includes a plurality of ports interconnected to one or more Customer Edge (CE) nodes and one or more Provider Edge (PE) nodes; and memory storing a forwarding table of routes, wherein the routes in the forwarding table are installed automatically based on static or Interior Gateway Protocol (IGP)-learned default routes, connected routes, Border Gateway Protocol (BGP) routes learned from peers, and routes in an Internet routing table, and wherein a number of the routes installed in the forwarding table is less than a number of routes in the Internet routing table. The number of routes in the Internet routing table exceeds a capacity of the memory, and the routes installed in the forwarding table ensure a loop-free topology. The routes installed in the forwarding table can include all of the BGP routes learned from peers plus longer prefix matches from the routes in the Internet routing table.

A method may include receiving a network schema including switches, links connecting the switches, and a topology that maps the switches to the links. The switches may include ports. The method may further include receiving a software defined networking (SDN) policy including a function that modifies a state of a packet entering a switch, converting the topology to a graph including nodes corresponding to the switches, while searching the graph, determining, according to the function, whether a port of a switch corresponding to a node is reachable by the packet entering the switch, and in response to searching the graph, verifying a property of the SDN policy.

Various systems and methods for performing bit indexed explicit replication (BIER) using multiprotocol label switching (MPLS). For example, one method involves receiving a packet that includes a MPLS label. The packet also includes a multicast forwarding entry. The method also involves determining, based on the value of the MPLS label, whether to use the multicast forwarding entry to forward the packet. The method further includes forwarding the packet.

Embodiments include an overlay multicast network. The overlay multicast network may provide a set of features to ensure reliable and timely arrival of multicast data. The embodiments include a congestion control system that may prioritize designated layers of data within a data stream over other layers of the same data stream. Each data stream transmitted over the network may be given an equal share of the bandwidth. Addressing in routing tables maintained by routers may utilize summarized addressing based on the difference in location of the router and destination address. Summarization levels may be adjusted to minimize travel distances for packets in the network. Data from high priority data stream layers may also be retransmitted upon request from a destination machine to ensure reliable delivery of data.

A network interface of a first computing device is configured to operate according to a bridge table. The bridge table defines a spanning tree protocol for a mesh network and identifies one or more reachable nodes. A communication characteristic between the first computing device and a second computing device of the one or more reachable nodes is determined to exceed a quality threshold. Based on the determination that the communication characteristic exceeds the quality threshold, the spanning tree protocol is overridden and the data is transmitted directly to the second computing device via a direct communication route.