Hitachi, Ltd.

Naoki Ono

Shigeki Satomi

Mami Oka

Kensuke Inoue

Mitsunobu Nagao

Hideaki Kano

In a network, an inter-network connection unit is connected to perform transmission of data between the network and another network. The inter-network connection unit is furthermore connected to a multiplexer. Between the multiplexer and another multiplexer to which an inter-network unit installed in the other network is connected, data transmission is performed via a multiplex line. The multiplexer changes the communication capacity of a communication line connecting the inter-network connection unit to the multiplexer in accordance with the data transmission quantity between the multiplexer and the inter-network connection unit connected thereto and dynamically changes the communication band assigned to the inter-network connection unit in accordance with the change of the communication capacity.

Method for dynamically assigning communication bands

A line switching apparatus for switching from a telecommunication line to a backup line in the event of occurrence of a fault on the telecommunication line includes a memory storing time zone information for monitoring the state of the telecommunication line, so that, when occurrence of a fault is detected during this monitoring time zone, the line switching apparatus switches from the faulty telecommunication line to a backup line, while when the time is outside the monitoring time zone, the state of the telecommunication line is not monitored so as to prevent unnecessary switching from the telecommunication line to the backup line.

Method and apparatus for line switching

A method of and apparatus for controlling a data transfer by a transfer deliverer node from a terminal equipment belonging to the transfer deliverer node to another node, in a network system having a plurality of nodes connected to a public switched network and a plurality of terminal equipments connectable to a corresponding node. At each node, a discriminator specific to each terminal equipment belonging to the transfer deliverer node is registered in advance in a first memory; a discriminator specific to a user of each terminal equipment is registered in advance in a second memory for each terminal equipment belonging to the transfer deliverer node; in response to a data communication request from the terminal equipment belonging to the transfer deliverer node, the discriminator of the terminal equipment and the discriminator of a user of the terminal equipment, respectively sent from the terminal equipment, are received; it is judged if the received discriminator of the terminal equipment is being registered in the first memory; it is judged if the received discriminator of a user of the terminal equipment is being registered in the second memory as a discriminator of the user of the terminal equipment; and in response to the judgment results, it is determined if a data transfer from the terminal equipment is permitted or not.

Method and apparatus for data transfer and circuit setting for

A network system in which a plurality of computers and a terminal device are connected to one another through a node by telecommunication lines, and one computer is designated by the terminal device to communicate data with the terminal device through the node, the node detects a stop or fault of the one computer, or a stop or fault of the telecommunication line connecting the one computer and the node to each other, in response to an incoming call for the one computer from the terminal device, and informs the terminal device of the stop or fault, in response to the detection of the stop or fault. The terminal device changes an address of the designated computer to perform the communication from an address of the one computer to an address of another computer, in response to the information of the stop or fault, whereby the terminal device issues a call to the another computer on the basis of the new address through the node, in the case where the one computer is designated as a computer to perform the communication, after the change of the address.

Network system and line switching method used therein

In a network system in which a line switching unit and the other line switching unit are connected with each other via communication lines and backup lines, and nodes which are connected with both the line switching units, respectively are adapted to communicate with each other via either one of the communication lines and backup lines and both line switching units, a line switching system wherein a network control unit is connected with the line switching units, said network control unit having, in a table, information on connecting mates of said communication and backup lines an information on a plurality of groups of communication lines each grouped based upon the former information, the network control unit being adapted to select a relevant group based upon the group information when a failure occurs in the communication lines for issuing an instruction for collectively switching a plurality of communication lines belonged to the group, whereby said line switching unit which has received the instruction performs switching to the relevant backup lines.

Line switching system

A network system includes a plurality of nodes connected to each other via line switching units through communication lines and backup lines and a network control unit connected to the line switching units. At an occurrence of a communication line failure, the network control unit supplies the line switching units with a line switching instruction to change over from the failed line to backup lines.

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Kawasaki, Japan

Naoki Ono