A method of communicating between nodes in a network where a node receives a sequence of symbols that will form a packet on a first communications channel and has a planned packet that it would send on a second communications channel. A destination is encoded into an arbitration portion of a header sequence of the packet, the header sequence comprising a sequence of symbols. The transmission on the second communications channel is as per the planned packet, for as long as the symbols of the planned packet match the symbols being received on the first channel. An arbitration decision is made when the symbols do not match, with the node either continuing to send the rest of the planned packet, or the rest of the packet being received on the first communications channel.

A safety network controller is comprised in an electronic safety system. The safety network controller comprises a first serial port and a second serial port, each of which is configured to communicatively connect to a redundant safety network controller via a respective daisy chain network. Each daisy chain network comprises at least one safety device controller that is controlling a corresponding safety device. The safety network controller further comprises network circuitry configured to communicatively connect to the redundant safety network controller via a packet-switched network. The safety network controller further comprises processing circuitry configured to exchange, with the redundant safety network controller: serial communication via each of the daisy chain networks; packets via the packet-switched network; and responsibility for control over one or more of the safety device controllers in response to detecting a failure.

A safety network controller is comprised in an electronic safety system. The safety network controller comprises a first serial port and a second serial port, each of which is configured to communicatively connect to a redundant safety network controller via a respective daisy chain network. Each daisy chain network comprises at least one safety device controller that is controlling a corresponding safety device. The safety network controller further comprises network circuitry configured to communicatively connect to the redundant safety network controller via a packet-switched network. The safety network controller further comprises processing circuitry configured to exchange, with the redundant safety network controller: serial communication via each of the daisy chain networks; packets via the packet-switched network; and responsibility for control over one or more of the safety device controllers in response to detecting a failure.

An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: determine that a packet data unit from a higher protocol layer entity is associated with a risk of survival time violation; and select between one or more first lower data protocol entities and one or more second lower protocol layer entities to process the protocol packet data unit.

An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: determine that a packet data unit from a higher protocol layer entity is associated with a risk of survival time violation; and select between one or more first lower data protocol entities and one or more second lower protocol layer entities to process the protocol packet data unit.

A control plane (CP) device switching method includes that when a user plane (UP) device in a forwarding-control separation system detects that performance of communication between the UP device and an active CP device does not meet a normal communication condition, and performance of communication between the UP device and a standby CP device meets the normal communication condition, the UP device sends a switching request to the standby CP device. When detecting that a quantity of UP devices that each send the switching request is greater than or equal to a first quantity threshold, the standby CP device may indicate each UP device in the forwarding-control separation system to switch to the standby CP device.

A control plane (CP) device switching method includes that when a user plane (UP) device in a forwarding-control separation system detects that performance of communication between the UP device and an active CP device does not meet a normal communication condition, and performance of communication between the UP device and a standby CP device meets the normal communication condition, the UP device sends a switching request to the standby CP device. When detecting that a quantity of UP devices that each send the switching request is greater than or equal to a first quantity threshold, the standby CP device may indicate each UP device in the forwarding-control separation system to switch to the standby CP device.

A wireless communication system includes three or more wireless communication apparatuses and a control apparatus, wherein the control apparatus includes a setting unit configured to determine, for each of a plurality of paths from a first one of the wireless communication apparatuses to a second one of the wireless communication apparatuses, a total product value being a result of computing a total product of arrival probabilities of radio frames of respective radio sections constituting the path and a search unit configured to select a path, among the plurality of paths, with the number of transmission times of the radio frame for each of the paths being a predetermined number of times or smaller and the total product value being a predetermined threshold or more.

A wireless communication system includes three or more wireless communication apparatuses and a control apparatus, wherein the control apparatus includes a setting unit configured to determine, for each of a plurality of paths from a first one of the wireless communication apparatuses to a second one of the wireless communication apparatuses, a total product value being a result of computing a total product of arrival probabilities of radio frames of respective radio sections constituting the path and a search unit configured to select a path, among the plurality of paths, with the number of transmission times of the radio frame for each of the paths being a predetermined number of times or smaller and the total product value being a predetermined threshold or more.

A communication system (50) according to the present invention includes a first communication device (10) that functions as a main device, and a second communication device (20) that functions as a backup device for the first communication device (10). A second functional unit of the second communication device (20) transmits a response request to a first functional unit of the first communication device (10), and transmits a transfer-destination switching request to the first communication device (10) if a response to the response request has not been received from the first functional unit. If a first transfer unit receives the transfer-destination switching request from the second functional unit, the first transfer unit switches a transfer destination of packets that should be processed by the second functional unit from the first functional unit to the second functional unit.