Hitachi, Ltd.

Kunio Hiyama

Yoshihiro Takiyasu

Eiichi Amada

Mitsuhiro Yamaga

Osamu Takada

Taihei Suzuki

Matsuaki Terada

Toshiki P Tanaka

Yukiji Yamauchi

Koichi Kimura

Yasuhiro Takahashi

Hirokazu Ihara

Kenji Kawakita

Naoya Kobayashi

Katsuyoshi Onishi

Kazunori Nakamura

Hideaki Ishida

Minoru Hatada

Haruyuki Nakayama

Hisao Kuma

Hiroo Takenouchi

Yasuhiko Hatekeyama

A high-speed ring LAN capable of accommodating at least one public network having a signal transmission rate of 155.57 MHz, and at least one sub-LAN having a signal transmission rate of 100 MHz. The high-speed LAN has a signal transmission rate of 155.52 Mbps .times.n (n is an even number). SONET (Synchronous Optical NETwork) subframes each comprising a 9 bytes .times.9 section overhead area and a 261 bytes .times.9 virtual container 4 (VC-4) area flow in a time-divisional n-multiplexed format. The respective node devices inserted in the transmission path have one or more ports to accommodate sub-LANs or public networks. Information is exchanged in units of a fixed-length packet between a received SONET subframe and an asynchronous port whereas information is exchanged in units of a byte between the SONET subframe and a synchronous port.

High-speed ring lan system

In a local area network composed of transmission lines for interconnecting a plurality of subordinate networks including synchronous apparatuses and a plurality of nodes which connect the subordinate networks to the transmission lines, information is transferred using a fixed length frame, a clock source which generates an independent clock signal and a circuit which generates a fixed length frame with the oscillation frequency of the clock source as a reference are provided in each node so as to adopt an independent clocking system, and distribution of a common synchronizing clock required for synchronous apparatuses is made by transmission while embedding transition point information of a synchronizing clock in a specific space in the fixed length frame. Further, each node generates a fixed length transmission frame with an independent clock signal, and on the other hand, there are provided in each node, from the requirement that information quantity applied to a network is made constant, a circuit for extracting a received clock, a storage device for storing received information temporarily, and an information outgoing quantity control circuit in which information quantity which is sent out in one frame is increased when the information quantity stored in the storage device becomes more than a predetermined first reference value and information quantity which is sent out in one frame is decreased when the information quantity stored in the storage device becomes less than a predetermined second reference value.

Independent clocking local area network and nodes used for the same

Frontend LANs connecting plural stations are connected to plural nodes of a backbone LAN respectively. The backbone LAN is constituted by plural physical or logical links, and each node corresponds to each frontend LAN. A first data block is segmented into one or plural second data block units of fixed length and transferred to destination nodes, a bridge is provided in order to assemble the second data blocks into the first data block. The bridge can transmit the second data blocks to arbitrary links, and the receiving is performed through one link. The bridge a decoder also has a decoder for decoding whether the learning should be performed or not, based on the learning indication information existing in the second data block including the routing information.

Bridge apparatus and a communication system between networks using the

A high-speed ring LAN capable of accommodating at least one public network having a signal transmission rate of 155.57 MHz, and at least one sub-LAN having a signal transmission rate of 100 MHz. The high-speed LAN has a signal transmission rate of 155.52 Mbps.times.n (n is an even number). SONET (Synchronous Optical NETwork) subframes each comprising a 9 bytes.times.9 section overhead area and a 261 bytes.times.9 virtual container 4 (VC-4) area flow in a time-divisional n-multiplexed format. The respective node devices inserted in the transmission path have one or more ports to accommodate sub-LANs or public networks. Information is exchanged in units of a fixed-length packet between a received SONET subframe and an asynchronous packet whereas information is exchanged in units of a byte between the SONET subframe and a synchronous port.

High-speed ring LAN system

Herein disclosed is a data communication system in which a plurality of node equipments are linked to a common signal transmission line so that the data may be communicated between the respective node equipments. The data communication system is characterized: in that at least one of the node equipments includes means for generating and transmitting repeatedly for a predetermined period the channel which contains a data transmission bit and a validity bit for the former bit; and in that each of the node equipments linked to the common signal transmission line partly sends out the data through said channel and partly makes the validity indicating bit indicate an invalid state, when the speed of said data is so slower than the predetermined period of said channel that the data to be sent out for the predetermined period are out of time thereby to make it possible to effect the data transmission at an arbitrary speed shorter than said predetermined period. Herein also disclosed is a data communication system in which a plurality of node equipments are jointed by a common transmission loop line and in which the information of multiple channels is repeatedly transmitted for a predetermined period to said transmission loop line so that the channel information may be sent and received between terminal equipments linked to said node equipments. The data communication system is characterized in that an identical pattern for synchronization is inserted into and transmitted by the plural head channels of each period so that the synchronization is effected at each of said node equipments by detecting the synchronizing pattern received by means of a detecting circuit.

Method and system for data transmission

A communication system in which a plurality of terminal devices connected to a loop transmission line perform data transmission/reception in a time-division multiplexing manner by using a communication frame circulating the transmission line. The communication frame being constituted by a plurality of sub-frames, each including a plurality of time slots. Each of the terminal devices is arranged to perform data transmission/reception using a designated time slot in a designated sub-frame. All the sub-frames in the communication frame are allotted to a terminal device of a high capability of data transmission, while less than all of the sub-frames are allotted to a terminal device of a low capability of data transmission. A plurality of low speed terminal devices, to which sub-frames different from each other have been respectively allotted, commonly use a time slot of the same number, so that each of the time slots in the communication frame can be effectively utilized.

Time-division multiplexing communication system for performing a

A text mailing system comprises a plurality of terminal equipments each connected to a telephone set to input and output a message and a mail control unit for receiving the messages from the terminal equipments through an exchanger and transmitting the received messages to the terminal equipments specified by the messages. Each of the terminal equipments inputs addressee identification information and the mail control unit transmits the messages to the terminal equipments on the condition of inputs of the addressee identification information for a specified type of message.

Text mailing system using a telephone line

In a loop bus network system where a plurality of processors are connected to a unidirectional loop bus and each of the processors generates a transmission message with a level number which designates the bus use priority of the message, each of node processors, in which message transmission request is generated, transmits to the loop bus a bus control data including a level number of the message generated therewithin and a data which represents the bus use priority assigned to each node processor for that level number. Each of the node processors compares the bus control data transmitted therefrom to a succeeding node with a control data received from a preceding node and then transmits only the larger data of the compared two data, thereby to ascertain that only one bus control data propagates around the loop and a loop bus use priority is assigned to one of the node processors that has generated the above-mentioned one bus control data.

Growing community of inventors

Fujisawa, Japan

Kunio Hiyama