A switch comprises: a register; a control entry holding part that holds control entries set by a predetermined control apparatus; a packet processing part that selects a control entry to be applied to a received packet by referring to a value on the register in addition to match conditions for the control entry; a register change part that changes the value on the register in a case where a change instruction for the value on the register is set to the control entry selected.

A method for maintaining continuity of a network signal path extending along a backplane includes providing a bypass signal circuit compatible with the network signal path and being electrically connected in series with the first and second portions of the network signal path. The bypass signal circuit includes a normally open circuit portion and an electrical contact movable with respect to the bypass signal circuit. An electrical contact is mechanically moved out of contact with the bypass signal circuit and moved mechanically into contact with the bypass signal circuit in response to the function module being detached from or attached to the function module electrical connector and not in response to an electrical control signal.

A method and system of determining the location of an earth fault within a loop of devices is disclosed. Upon the detection of an earth fault within the loop comprising a plurality of devices, a first device within the loop is isolated along with a second device. While the first device and the second device are isolated, it is determined if the earth fault still exists. If the earth fault no longer exists, then determine that the earth fault is located between the first device and the second device. This can be iterated through each adjacent pair of devices in the loop to localize the earth fault between the devices.

A method and system of determining the location of an earth fault within a loop of devices is disclosed. Upon the detection of an earth fault within the loop comprising a plurality of devices, a first device within the loop is isolated along with a second device. While the first device and the second device are isolated, it is determined if the earth fault still exists. If the earth fault no longer exists, then determine that the earth fault is located between the first device and the second device. This can be iterated through each adjacent pair of devices in the loop to localize the earth fault between the devices.

A communication device with an activated ring controller provided in both first and second subnetworks for data transmission in a redundantly operable communications network, which includes at least one first and one second subnetwork, which each include communication devices interconnected within a ring topology, wherein the subnetworks are interconnected via coupling line sections to which coupling communication devices are connected, where the coupling line section to which a selected coupling communication device is connected is operated as an inactive reserve coupling line section until a disruption occurs, whilst another coupling line section is operated as an active main coupling line section, where coupling communication devices connected to the main coupling line section transmit status datagrams to the selected coupling communication device which additionally include configuration information about whether the particular coupling communication device connected to the main coupling line section is an activatable ring controller.

A communication device with an activated ring controller provided in both first and second subnetworks for data transmission in a redundantly operable communications network, which includes at least one first and one second subnetwork, which each include communication devices interconnected within a ring topology, wherein the subnetworks are interconnected via coupling line sections to which coupling communication devices are connected, where the coupling line section to which a selected coupling communication device is connected is operated as an inactive reserve coupling line section until a disruption occurs, whilst another coupling line section is operated as an active main coupling line section, where coupling communication devices connected to the main coupling line section transmit status datagrams to the selected coupling communication device which additionally include configuration information about whether the particular coupling communication device connected to the main coupling line section is an activatable ring controller.

A web handling system is described, including a plurality of web handling controllers and a web handling process logic controller networked to form a ring network. A processor of the web handling process logic controller being configured to determine whether a fault exists within the ring network, and responsive to determining that a fault exists within the ring network, to generate and send signals throughout the ring network to switch the configuration of the ring network to at least one linear network.

A web handling system is described, including a plurality of web handling controllers and a web handling process logic controller networked to form a ring network. A processor of the web handling process logic controller being configured to determine whether a fault exists within the ring network, and responsive to determining that a fault exists within the ring network, to generate and send signals throughout the ring network to switch the configuration of the ring network to at least one linear network.

The conventional relay device has a problem that a traffic load on a communication device is large when an output port of a frame including a destination address, which an address table has not learned yet, is a port connected to a branch circuit, since flooding is performed on all ports except for a port that has received the frame. A relay device (21) is provided with a destination determination unit (41) to transfer, when a time clocked by a timer unit (40) to start clocking is within a set time, a frame to ports (511 and 512) connected to trunk circuits (61 and 64), and when the time clocked by the timer unit (40) exceeds the set time, to transfer the frame to the ports (511 and 512) connected to the trunk circuits (61 and 64) and a port (513) connected to a branch circuit (65), in a case wherein it is impossible for a search unit (43) to obtain from a first storage unit (33) a port number corresponding to a destination address included in the frame received, and the first storage unit (33) is cleared.

A wiring system for an automobile connecting a processor and a plurality of devices, using one or more backbone sections. The processor and devices are connected to one another to form a first loop and a second loop, such that data may be transmitted along the first loop and data may be transmitted along the second loop.