Hitachi, Ltd.

Tatsuo Kawatobi

Satoshi Miyazaki

Kazuo Yagyu

Hidenobu Taniguchi

Sinichi Kouyama

Toshiaki Hirata

Jiro Kashio

Keizou Mizuguchi

Masakazu Furuya

Koshi Furuhashi

In a communication system having a plurality of host computers and two communication control processors (CCPs) connected to the respective host computers, one CCP is used as a regular CCP and the other CCP as a backup CCP. Each host computer establishes links with the two CCPs. Each of the host computers has a link flag for each link connected to each of the CCPs. The flag is set when the link is connected to the regular CCP. When the master host computer detects failure of the regular CCP, the master host computer sends an activate node request to the backup CCP to indicate that the backup CCP should be activated. Upon reception of the activate node request, the backup CCP sends a change output link request to all of the host computers. Upon reception of the change output link request, each of the host computers sets the link flag corresponding to the backup CCP to deal with the backup CCP as a regular CCP.

System for switching between first and second control unit and

There is a communication system comprising: an integrated services digital network (ISDN) having a plurality of information channels (Bch) and at least one control channel (Dch); a CPU (host computer) connected to said ISDN through a communication control processor (CCP); and a plurality of packet terminals connected to the ISDN. In the communication system, when a call request from the CPU or an incoming call request from one of the packet terminals is input to the CCP, if the B channel data link connection or the D channel data link connection for the packets has already been established between the CCP and the ISDN, the CCP selects the channel data link connection as a channel for communication with the packet terminal and multiplexes a plurality of calls to the same channel even if the other space B channels exist.

Data link control method and system for integrated services digital

A charging system in a data communication network, there are disposed a first unit for negotiating, prior to effecting a data communication between a calling terminal and a called terminal via the network, charge ratio associated with the calling and called terminals therebetween so as to allow the calling terminal to initiate the data communication on the understanding that the calling terminal and the called terminal agree on the charge ratio, a second unit for charging the calling terminal and the called terminal based on the charge ratio at a disconnection of the call, and a third unit for respectively notifying charge information to the calling terminal and the called terminal.

Charging system in data communication network

Herein disclosed is a communication network, in which two terminal nodes transmit and receive messages containing a destination node discriminator and a source node discriminator by way of a communication route composed of at least one relay node and a plurality of information links connecting the terminal nodes and the relay node. In this communication network, the relay node is stored in advance, in accordance with the combination of a destination node and a source node, with both the information link for transmitting the messages received and the flag information indicating the establishment of the communication route from said source node to the relay node itself. When any of the terminal nodes designates the other terminal node as the destination node and transmits the control message for the communication route establishment to the destination node, the relay node having received the control message sets the flag information, which corresponds to the combination of the source node and the destination node, in a state indicating the link establishment, and transmits said received message to said information link in case the information link corresponding to said combination is in the connected state. The relay node on the communication route transmits the control message to an adjacent node, when it detects the state change of the adjacent information link, under a condition that the flag information corresponding to said information link is in the set state.

Growing community of inventors

Yokohama, Japan

Tatsuo Kawatobi