Hitachi, Ltd.

Hitachi Software Engineering Company, Ltd.

Hitachi Computer Eng. Co., Ltd.

Hitachisoftware Eng. Co., Ltd.

Hitachitelecom Tech. Ltd.

Hisashi Matsumura

Hiroyuki Wada

Fumiaki Matsuura

Susumu Nakayashiki

Tokuhiro Niwa

Atsushi Ugajin

Toyokazu Hashimoto

Masahiko Kida

Kazuhiro Ushijima

Jiro Kashio

Yoshihito Sako

Ihei Kajiya

Yoshiyuki Sato

Masahide Kouhei

Tsutomu Koita

Yasunobu Hori

A web phone dialer system that can easily transmit a call to a person, even if the telephone number of the person is changed. The web phone dialer system includes a web server, a sending client, and a receiving client each being connected to each other through a network. The web server includes a telephone directory database which stores a database file having a plurality of records each including an assignment, name, and telephone number of a parson operating a receiving client and an IP address, and mail address if the receiving client. The web server in response to an inquiry from a sending client, including at least one of an assignment and name of a person to which communication is to be established, searches the telephone directory database to obtain the telephone number, IP address and mail address of the person. The sending client use the telephone number to call.

Web phone dialer system apparatus and method

A network management system includes network stations each having a power source and a power switch to turn the power source on and off, a network management station to monitor the network stations, and a communication network enabling connections between the network stations and the network management station. When turned off by the power switch, the network station enables communication with the network management station and then sends an event to notify the power-off state thereto. This enables the network management system to display whether the communication failure is caused by a network failure or the power-off of the network station.

Network station and network management system

In a ring LAN system having a configuration control unit serially connected to a dual ring transmission line, the configuration control unit is provided with a transmission line reconfiguration control mechanism to disconnect a fault point upon detection of a transmission fault, such as a breaking of one of a twisted pair of cables, and after recovery of the fault, reconnect the disconnected point to restore the transmission line to its original state. The reconfiguration control mechanism suspends reconfiguration control if a reconfiguration operation counter counts more than a predetermined number of reconfiguration operations within a predetermined time period measured by a reconfiguration operation monitor timer, such as when a temporary fault occurs intermittently. However, operation of such reconfiguration control suspension is initially suspended after system start up, such as when transmission line signals are attenuated and appear as faults, until after an elapsed time after system start up measured by a lapse time timer reaches a preselected time period. Operation of the reconfiguration control mechanism is controlled by a reconfiguration management mechanism.

Control system for configuring ring LAN with improved reconfiguration

In a buffer management system for communication apparatus, the statistical information to be collected at each station such as the number of occurences of receiver buffer busy state is counted at regular time intervals for a preset time duration, and if it becomes in excess of a predetermined number, the ratio in size of transmitter buffer area to receiver buffer area is changed in accordance with the buffer busy state number such that the size of the receiver buffer area becomes larger.

Buffer management system

A method for performing a duplicated address test used for a network including a first ring transmission line, a second ring transmission line having a signal transmission direction opposite to that of the first ring transmission line, and a plurality of stations connected to at least one of these ring transmission lines. Each of these stations has a flag DAC representing whether or not the duplicated address test is performed, and some of the plural stations constitute a plurality of control nodes having a configuration function of the network. The flag DAC of each of the stations is reset at a time instant when a power source of this station is turned on, and also when any of the control nodes receives the sent out configuration control frame. Each of the stations having the reset flags DAC sents out the duplicated address test frame to either the first or second transmission line to which the station is connected when a token frame to control a transmission right is captured. When another station having the same address as that of a source station receives the test frame, a discriminator indicative of an address duplication is added to this test frame.

Method and apparatus for testing station address in network

In a loop communication system in which a plurality of stations connected to a pair of loop transmission lines comprised of a main transmission line and a preparatory transmission line communicate with each other through the loop transmission lines, one of the transmission lines has to be looped back to the other when failures occur in both the transmission lines by escaping from a point at which the failures occur. When the master station sequentially transmits loop back command signals to slave stations connected to the loop transmission lines, it takes into consideration the number of slave stations present between the master station and an interrogated slave station inclusive thereof so as to vary the monitoring time in accordance with a turn around time required for the master station to receive a response signal sent from the interrogated slave station being in receipt of a loop back command signal, thereby reducing the time for loop back.

Loop back control system

This invention relates to a loop transmission system which has a plurality of stations connected to a loop transmission path to transmit data among the stations. In the transmission frame to be sent out from the sending station, specific information is included for identifying each frame and this information is held in the sending station. When the transmission frame returns to the sending station after being transmitted through the loop transmission path, the specific information in the frame is received and compared with the information held in the station and, if they coincide, it is decided that the transmission frame has been correctly received by the intended receiving station.

Data transmission system adapted to facilitate detection of safe receipt

A loop transmission system including a plurality of stations connected in series in a looped transmission line to transfer data among the stations, wherein the stations include a supervising station and at least one terminal station and the transmission line is duplicated so that when a fault occurs in currently used one of the transmission lines, the other transmission line which has been used as a spare is used for transmission of data, while the supervising station sends out a specific signal to the spare transmission line and the terminal stations each determines one of the transmission lines through which the specific signal is detected, as the spare.

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Odawara, Japan

Hisashi Matsumura