Abstract: 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.

Abstract: The following description is directed to managing routing resources of a communication network. In one example, a method can include determining an amount of routing capacity from a network device and toward a routing prefix. An attribute associated with the routing prefix can be modified based on the amount of routing capacity toward the routing prefix. The modified attribute associated with the routing prefix can be announced to a peer of the network device.

Abstract: The following description is directed to managing a hierarchical network including one or more network zones. In one example, a method of managing a hierarchical network includes collecting network state from respective devices of a network zone; using the collected network state to build an aggregated topology of the network zone; and transmitting the aggregated topology of the network zone to a traffic engineering service.

Abstract: A first role manager of a distributed service determines that a leadership assignment decision is to be made with respect to a particular node of the service. The first role manager identifies a particular role indicator value from a first subset of a set of role indicator values according to a value selection order of a role assignment policy of the service. The first role manager is not permitted to assign values from a different subset of the first set of role indicator values. The particular role indicator value is transmitted to the particular node, enabling the particular node to fulfill at least a first category of service requirements corresponding to the role of leader node.

Abstract: Network packet tracing may be implemented on packet processors or other devices that perform packet processing. As network packets are received, a determination may be made as to whether tracing is enabled for the network packets. For those network packets with tracing enabled, trace information may be generated and the network packets modified to include the trace information such that forwarding decisions for the network packets ignore the trace information. Trace information indicate a packet processor as a location in a route traversed by the network packets and may include ingress and egress timestamps. Forwarding decisions may then be made and the network packets sent according to the forwarding decisions. Tracing may be enabled or disabled by packet processors for individual network packets. Trace information may also be truncated at a packet processor.

Abstract: Network links are exercised by transmitting network frames across the links at a threshold level of network traffic by filling unutilized bandwidth with test frames. By increasing network traffic across the links, errors are increased and easier to detect. The test frames can be given lower priority than customer traffic so as not to impact the test traffic. The test frames can be designed such that they are dropped upon receipt by another network switch.

Abstract: Methods, systems, and devices are described for transmitting and storing routing path information and routing topology information using a single protocol. In particular embodiments, routing path information for an exterior gateway protocol (“EGP”) network such as a border gateway protocol (“BGP”) network is transmitted throughout an interior gateway protocol (“IGP”) network using IGP messages such as open-shortest-path-first (“OSPF”) or intermediate state to intermediates state (“IS-IS”) messages. The IGP networks may transmit and store the BGP information using type length values (TLVs). As a result, network areas running an IGP may maintain BGP information throughout the network area without the overhead of an iBGP mesh and related message-passing.

Abstract: Indirect destination determinations for forwarding tunnel network packets may be performed. Tunneling may be initiated for network packets received at a packet processor according to a forwarding route or other prior packet processing stage, such as an access control list stage. A corresponding entry in a tunnel lookup table may be accessed to determine the tunneling to be applied to the network packet, such as Internet Protocol tunneling or Multiprotocol Label Switching tunneling. The corresponding entry may also include a pointer to a next hop address table that stores a next hop address for the tunneled version of the network packet. The tunneled version of the network packet may be forwarded to the next hop address.

Abstract: A method for adjusting capacity in a multi-stage routing network includes monitoring a number of available connections between a router in a first stage of a multi-stage router network and one or more routers in a second stage of the multi-stage router network. Each of the stages of the multi-stage router network may include a plurality of routers. The method may also include detecting that the number of available connections falls below a threshold number. A notification can be sent to one or more routers in a third stage of the multi-stage router network that the router in the first stage is deprioritized. The one or more routers in the third stage can be operated so that communications to the first stage are routed to one or more other routers in the first stage.

Abstract: Techniques and solutions for distributing routing updates using timing information are described. For example, inter-device messaging protocols can support timing information (e.g., routing protocols be extended to support timing information). The timing information can indicate a time at which the routing update is to be put into effect where the time decreases the further away a given routing device is from the source of the routing update. For example, each routing device can determine a decayed update reference time when the given routing device will put the routing update into effect according to a decay mode. Routing updates can be managed between routing devices that support timing information and routing devices that do not support timing information.

Abstract: Techniques and solutions for distributing routing updates using timing information are described. For example, inter-device messaging protocols can support timing information (e.g., routing protocols be extended to support timing information). The timing information can comprise an indication of a time at which the routing update is to be put into effect. Using the timing information, a number of routing devices can put the routing update into effect at the same time (e.g., at an update reference time) according to a synchronous mode. Routing updates can be managed between routing devices that support timing information and routing devices that do not support timing information.