A method implemented by a first controller in a network comprising a cluster of controllers including the first controller and a second controller, the method comprises transmitting, to a network element (NE), a first BGP message comprising a first controllers network layer reachability information (NLRI), the first controllers NLRI carrying a position of the first controller relative to other controllers in the cluster of controllers, receiving, from the NE, a second BGP message comprising a second controllers NLRI, the second controllers NLRI carrying a position of the second controller relative to the other controllers in the cluster of controllers, and determining the primary controller from the cluster of controllers based on the position of the first controller and the position of the second controller, with the primary controller being responsible for controlling the network.

A method implemented by a first controller in a network comprising a cluster of controllers including the first controller and a second controller, the method comprises transmitting, to a network element (NE), a first BGP message comprising a first controllers network layer reachability information (NLRI), the first controllers NLRI carrying a position of the first controller relative to other controllers in the cluster of controllers, receiving, from the NE, a second BGP message comprising a second controllers NLRI, the second controllers NLRI carrying a position of the second controller relative to the other controllers in the cluster of controllers, and determining the primary controller from the cluster of controllers based on the position of the first controller and the position of the second controller, with the primary controller being responsible for controlling the network.

Safe, fast, acyclic routing in a communications network includes receiving at a local router, from a first router, a request packet that indicates a first destination value. In response to the request, it is determined whether a first entry in a routing table data structure at the local router indicates the first destination value in a destination field and a valid value in a voucher field. The local router sends to the first router a response packet with a first distance value from a distance field of the first entry only when the voucher field holds a valid value. The local router forwards the request packet to a different second router when the voucher field holds an invalid value.

Safe, fast, acyclic routing in a communications network includes receiving at a local router, from a first router, a request packet that indicates a first destination value. In response to the request, it is determined whether a first entry in a routing table data structure at the local router indicates the first destination value in a destination field and a valid value in a voucher field. The local router sends to the first router a response packet with a first distance value from a distance field of the first entry only when the voucher field holds a valid value. The local router forwards the request packet to a different second router when the voucher field holds an invalid value.

A method and apparatus form and/or define a network topology in a Layer 3 network with a plurality of nodes, where each node has at least one interface. To that end, the method defines a plurality of neighborhoods, and assigns at least one interface of each node to at least one of the neighborhoods. The method also assigns a communication role to each interface so that each communication role is effective relative to one of the plurality of neighborhoods. The method then enables communication between the interfaces of the plurality of nodes as a function of the neighborhoods and the communication roles.

A method and apparatus form and/or define a network topology in a Layer 3 network with a plurality of nodes, where each node has at least one interface. To that end, the method defines a plurality of neighborhoods, and assigns at least one interface of each node to at least one of the neighborhoods. The method also assigns a communication role to each interface so that each communication role is effective relative to one of the plurality of neighborhoods. The method then enables communication between the interfaces of the plurality of nodes as a function of the neighborhoods and the communication roles.

Methods, systems, and apparatus, for automatically changing a network system. A method includes receiving a set of first intents that describe a state of a first switch fabric; receiving a set of second intents that describe a state of a second switch fabric; computing a set of network operations to perform on the first switch fabric to achieve the second switch fabric, the set of operations also defining an order in which the operations are to be executed, and the set of operations determined based on the set of first intents, the set of second intents, and migration logic that defines a ruleset for selecting the operations based on the set of first intents and the second intents; and executing the set of network operations according to the order, to apply changes to elements within the first switch fabric to achieve the state of the second switch fabric.

Methods, systems, and apparatus, for automatically changing a network system. A method includes receiving a set of first intents that describe a state of a first switch fabric; receiving a set of second intents that describe a state of a second switch fabric; computing a set of network operations to perform on the first switch fabric to achieve the second switch fabric, the set of operations also defining an order in which the operations are to be executed, and the set of operations determined based on the set of first intents, the set of second intents, and migration logic that defines a ruleset for selecting the operations based on the set of first intents and the second intents; and executing the set of network operations according to the order, to apply changes to elements within the first switch fabric to achieve the state of the second switch fabric.

A standby routing fault-tolerance unit obtains a plurality of inbound routing packets of a first routing processing unit by using a forwarding unit and an active database unit. The first routing processing unit is a routing processing unit corresponding to an active routing fault-tolerance unit. The standby routing fault-tolerance unit sends the plurality of inbound routing packets of the first routing processing unit to a second routing processing unit. The second routing processing unit is a routing processing unit corresponding to the standby routing fault-tolerance unit.

A multichassis link aggregation method includes receiving, by a first network device, n pieces of second information of n second network devices. The first network device and the n second network devices are in a multichassis link aggregation group (MC-LAG), n is an integer greater than or equal to 1, the n pieces of second information include n second port keys, and the n pieces of second information are in one-to-one correspondence with the n second port keys. The method also includes determining, by the first network device, a third port key based on a first port key of the first network device and the n second port keys. The third port key is an MC-LAG configuration parameter of the first network device.