Abstract: Modules of a network switch receive data transmissions from network stations via its I/O ports, each data transmission including an address of a source network station sending the transmission and an address of a destination station to receive the transmission. Each module receiving a data transmission either passes it on to a next module of the network switch via a ring bus or forwards it to the destination station when it is accessible via one of the module's own I/O ports. Each module includes an address translation unit mapping the network address of each station to the particular I/O port though which that network station communicates. The address translation unit updates its address-to-port mapping when a data transmission arrives at an I/O port from a source station having an unmapped or incorrectly mapped address, and then sends a mapping instruction to address translation units of all other switch modules via the ring bus telling them to similarly update their network address mappings.

Abstract: A hub port in a Fibre Channel loop for detecting and bypassing attached node ports in an OLD-PORT state is disclosed. The hub port includes a hub data source, a detect circuits, and an output control circuit. The hub data source supplies data to the hub port from a Fibre Channel loop. The detect circuit is configured to detect a valid non-Arbitrated Loop sequence from an attached node port indicating that the node port is in an OLD-PORT state. The output control circuit operates to bypass the node port from the loop when the valid non-Arbitrated Loop sequence is detected.

Abstract: A network switch for network communications, wherein the network switch includes at least one data port interface supporting a plurality of data ports transmitting and receiving data at a first data rate and a second data rate. The at least one data port interface includes an ingress logic circuit in communication with the at least one data port interface for generating at least one of an ingress address resolution and a filtering search request. A CPU interface is provided and configured to communicate with a CPU. A shared hierarchical memory structure including an internal memory in communication with the at least one data port interface, and an external memory in communication with a memory management unit via an external memory interface is provided. A communication channel is provided for communicating data between the at least one data port interface, the internal memory, the CPU interface, and the memory management unit.

Abstract: An improvement is disclosed for a Totem system having a network and a plurality of host processors connectable to the network, each of which host processors includes a CPU and is configured for executing processes, wherein the improvement includes, for each host processor, a buffer memory and a co-processor for each host processor. The buffer memory is electrically connected to the CPU and configured for storing messages sent to or from the CPU. The co-processor is electrically connected for providing an interface between the network and the host processor, and is configured for responding to tokens and for delivering messages from the network to the buffer memory for retrieval by the CPU, and for delivering to the network messages stored in the buffer memory by the CPU.

Abstract: Line or shop replaceable units (LRUs or SRUs) of a vehicle entertainment system are programmed as microservers to receive and carry out requests for testing the LRUs/SRUs from a browser connected to the LRUs/SRUs over a communications network of the vehicle entertainment system. Test results are transmitted back to the browser for display. The browser may be part of the vehicle entertainment system or remotely connected to the communications network of the vehicle entertainment system. Hyper-Text Transfer Protocol (HTTP) is used as the protocol for transporting the requests and the execution results over the communications network, and so, the programming of the LRUs and the SRUs may be achieved with a standard HTTP server program and the browser may be any HTTP-compliant browser such as Netscape Navigator™ and Internet Explorer™.

Abstract: A communication frame has a counter value which is updated each time the communication frame passes through a node, and a source address. Therefore, upon receiving the communication frame, the node references a source address to check to see if the communication frame was generated by the node, that is, if the communication frame is a returned frame. In addition, even when the node finds that the received communication frame is not the communication frame generated by this node, the node checks counter value information in the communication frame to check to see if the communication frame has already circulated around the network, that is, if the communication frame is abnormal. Furthermore, because the counter value information is provided in each communication frame, the present invention is compatible with a system where a plurality of communication frames are on a network at the same time.

Abstract: Address defined session management permits data interchange across a stateless channel utilizing the existing addressing protocol in a particular communications channel without altering the body of the message itself. By establishing a session identifier, applications and/or users can engage in interactive data communications through any stateless communications channel with any corresponding application that requires interactive communication.

Abstract: A hub port in a Fibre Channel loop for detecting and bypassing attached node ports in an OLD-PORT state is disclosed. The hub port includes a hub data source, a detect circuits, and an output control circuit. The hub data source supplies data to the hub port from a Fibre Channel loop. The detect circuit is configured to detect a valid non-Arbitrated Loop sequence from an attached node port indicating that the node port is in an OLD-PORT state. The output control circuit operates to bypass the node port from the loop when the valid non-Arbitrated Loop sequence is detected.

Abstract: A method and an apparatus for transmitting data in a linear-type or ring-type network structured by a plurality of nodes and both-way transmission lines each connecting between adjacent nodes includes that each node operates as a left TE, a right TE, or an IE. The left and right TEs prepare token packets each including a transmission right and packet trailers each including data packet storage area. The left TE transmits the packet trailers on a right direction line of the both-way transmission line.

Abstract: An improved frame processing apparatus for a network that supports high speed frame processing is disclosed. The frame processing apparatus uses a combination of fixed hardware and programmable hardware to implement network processing, including frame processing and media access control (MAC) processing. Although generally applicable to frame processing for networks, the improved frame processing apparatus is particular suited for token-ring networks and ethernet networks. The invention can be implemented in numerous ways, including as an apparatus, an integrated circuit and network equipment.

Abstract: In the situation that data switching is incorporated in a wide area telecommunications network it is advantageous to use a local area network protocol such as ethernet which allows network resources to be shared. However, this introduces a problem with respect to loops in the network and the possibility of infinite packet looping. If the known spanning tree algorithm is used to prevent infinite packet looping this is problematic because the known algorithm takes a relatively long time to take effect. An algorithm is described which is based on assumptions about the topology of the communications network and which is simpler and faster.

Abstract: A network and a coupling device for connecting two segments in such a network. The coupling device has means (510 for measuring the slot time configured in the users by means of so-called GAP queries with which active users (201 . . . 206) using the PROFIBUS DP protocol for data transmission cyclically check whether new users have been connected to the network. Based on this slot time, coupling devices obtain information on the extent of the network, which is required for certain monitoring mechanisms. Further, a network and a coupling device for connecting segments in such a network, which has means (63, 64, 73, 78) for detecting corruption of a message by faults on a segment (16) and blocking the onward transmission of messages received on the faulty segment (16). The coupling devices (22, 23) connected to the faulty segment (16) block and reauthorize onward transmission almost simultaneously so that no unidirectional connection is established.

Abstract: A data network hub unit is stackable with other such units to constitute a hub in which each of the units can supply data packets to network data destinations and receive data packets from network data sources, and to form a closed data transmission ring which enables packets received at any unit to be transmitted from any other unit. The hub unit includes arbitration control means responsive to packet headers circulating on said ring.

Abstract: A master station 11 produces a token packet for isochronous data in which a slave station 12 and slave stations 13 and 14 serving as a sending station and receiving stations are designated using IDs for isochronous data “#2” and “#3” in accordance with contents described in a table 161 held in its inner part so as to manage a transmission bandwidth using a token packet sending/analysis executing device 16, and sends out the produced token packet to a transition path 15 on the downstream side. The slave station 12 sends out an isochronous data packet 42 using the token packet for isochronous data 41. According to the token packet for isochronous data 41, the slave stations 13 and 14 are designated as receiving stations using the ID for isochronous data “#3”, so that the slave stations 13 and 14 perform the above-mentioned operations, to receive the isochronous data packet 42.

Abstract: First, communication data are transmitted from an arbitrary originating source communication device to the other plural destination communication devices. When receiving the communication data, the respective destination communication devices which receive the communication data make responses including the receiving states of the communication data to the originating source communication device, and thereafter change a next destination of the communication data into a next address according to the description contents of a destination identifier read from the memory as next address storage means so as to transmit the communication data whose destination was changed to the communication device corresponding to the next address.

Abstract: A multi-port LAN switch is provided that enables attached network devices to both communicate directly and to insert into a token-ring network through an attached concentrator. Each port of the multi-port LAN switch has a first transformer, a second transformer, and a switching system. The first transformer has a first winding connected to a first connection of the port. The second transformer has a first winding connected to a second connection of the port. The switching system switches to a port mode or an adapter mode as a function of a mode signal transmitted to the port In the adapter mode, the switching system connects a second winding of the first transformer to a transmitter circuit in the port, and its connects a second winding of the second transformer to a receiver circuit in the port.

Abstract: A network for interconnecting network equipment units via a ring optimizes access to the ring by the equipment units in that the capacity of the ring is permanently shared between the various equipment units. An information signal, representing the unused part of the capacity of the ring, is forwarded on the ring. The equipment units insert into a transport frame a number of data units corresponding to a minimum transmission right guaranteed to each equipment unit. The unused capacity of the ring is then subdivided between the equipment units.

Abstract: A port for connecting a node to a network loop is disclosed. The port includes a detect element, a frame termination generator, a buffer data generator, a switching element, and a control element. The detect element monitors data from the node and sets an error flag when invalid data is received at the port. The frame termination generator generates frame termination primitives. The buffer data generator generates buffer data. The switching element has a control input, an output, and a plurality of data inputs. Each of an output of the node, the upstream node, the frame termination generator, and the buffer data generator is connected to a corresponding data input. The control element is connected to the detect element and the control input of the switching element. The control element selects, according to the error flag, one of the data inputs of the switching element. The selection connects to the output of the switching element to be output by the port to a downstream node.

Abstract: A method of inserting an end station (6-8) into a token ring network (2). The end station (6-8) attempts to open into the ring network in one insertion mode, the end station responding to an insertion error code relating to an insertion event, before the end station applies phantom drive, to change from one insertion mode to another insertion mode. A change of insertion mode is a change in at least one of end station speed and end station idling speed.

Abstract: An apparatus for accelerated Fiber Channel protocol handshaking and data exchange involves dividing a Fiber Channel arbitrated loop architecture up into a plurality of arbitrated subloops, each of which arbitrates locally using the same fundamentals as the Fiber Channel arbitration protocol but with some slight modifications which do not affect the compatibility of standard Fiber Channel nodes. Each subloop is coupled to a hub port which contains a state machine which implements distributed intelligence to do switching function and fill word generation to implement the accelerated protocol by using a plurality of switching, fill word generation and token passing rules. The state machine in each hub port is coupled to its local subloop and to its neighboring hub ports through a single TDMA bus which has timeslots dedicated to carrying broadcast loop and return loop traffic and control token traffic.

Abstract: The present invention provides a method and apparatus for removing unwanted data packets from a ring topology communication network having a plurality of nodes. The invention ensures that a data packet is removed from the network if there is a failure of the originating node, or if there is a failure of the node principally responsible for removing the data packet. The invention provides fault-tolerance, without significantly adversely affecting the overall network performance. The invention provides the originating node address in a controlled field of the data packet, with unused data bits within the control field being used as "rouge packet bits." The invention will include one or more nodes designated as "rouge data packet removal nodes" or "rouge removal nodes." A data packet is created at an originating node which will embed its own address in a "Node ID" field of the data packet and will transmit the data packet along the network.

Abstract: A network interface device includes a random access memory used as a transmit and receive buffer for transmission and reception of data frames between a host computer bus and a packet switched network. The network interface device includes read and write controllers for each of the transmit and receive buffers, where each write controller operates in a clock domain separate from the corresponding read controller. The read and write controllers output status information corresponding to the reading or writing of a stored data frame in the receive buffer. The memory management unit includes a synchronization circuit, which arbitrates updates to the holding registers by the read and write controllers based on the asynchronously determined presence of at least one stored data frame.

Abstract: In a fiber channel network, a method and system for discovering the location of a storage device that does not support FARP using a FARP broadcast using a storage router as a proxy. The storage device can be connected to the storage router via an arbitrated loop or a local SCSI interface. The storage router can perform a discovery to determine the node names of each storage device connected to it and save the discovered storage device node names to a look-up table. The storage router then sends a FARP request to each storage device on the look-up table. For each storage device that responds, flagging the corresponding node name for that storage device in the look-up table as FARP compatible, and for each storage device that does not respond, flagging the corresponding node name as not being FARP compatible.

Abstract: Several nodes are connected to a ring structure by means of communication lines in a network for packet-oriented data traffic. Each node is connected to lines of the ring structure. A buffer circuit is provided between the high speed interfaces for reading a routing information on the head of a data packet. The buffer circuits are structured in such a manner that the delay time in the transit traffic is smaller than, for example, 10 .mu.s. Several users are connected at the node. A wait line circuit is provided for each user. A controller ensures the processing of the data packets in the transit, insert and extract modes.

Abstract: A network interface device having a random access memory for buffering data between a host bus interface and a media access controller includes a buffer controller configured for storing a data frame in combination with tracking and status information associated with the storage of the data frame. The memory controller is configured for writing receive frame data received from a media access controller into the random access memory. The tracking and status information is stored in memory locations contiguous with the data frame to enable a read controller operating in a separate clock domain to access the status information and the corresponding data frame as a single data unit. Moreover, the disclosed embodiment stores the status information at the beginning of the stored data unit, enabling a controller reading the buffer memory to immediately determine the status of the corresponding stored data frame.

Abstract: A ring topology based architecture for a local area network. The transmission medium is unshielded twisted-pair wire. A set of two such twisted-pairs are used to connect the nodes of the network together, with the transmit twisted-pair wires from one node being connected to the receive twisted-pair wires of the next node. When a node of the network is powered up, a relay is opened which disconnects the incoming receive lines from the outgoing transmit lines. This brings the node on line. The relay is controlled via software command and a timer which is used to take a preceding node off-line for a predetermined period in the event jabber from that node is detected. A 16 byte FIFO bypass built into the medium access control hardware of the system is used to reduce the ring latency which normally results from the need to store entire data packets at each node, prior to the packet being forwarded.

Abstract: A method and apparatus for a node being inserted into a token ring local area network to sense the data transmission speed of the token ring LAN and automatically setting the data transmission speed of the node to match the data transmission speed of the token ring LAN. The token ring LAN may operate at either 4 megabits per second or 16 megabits per second. The node recovers data transmitted on the token ring, and determines, based thereon, the speed of the data transmission and configures the speed at which the node transmits and receives data to/from the token ring network accordingly.

Abstract: A ring data network (such as a token ring network) is divided by a security unit (1) into first and second segments (6 and 8). The second segment (8) typically corresponds to one security group in the network. Logic in the security unit reads appropriate parts of each frame (typically the two address segments) to determine whether it is appropriate to forward the frame to the next segment of the ring. If the frame does not need to go to the next segment, or is not authorized to do so, then the security unit forwards instead a modified form of the frame in which its data cannot be read (except possibly by the security unit itself). In most cases the data content of the frame will be stored in the security unit. When the modified frame returns to the security unit at its second input port (4), the original frame can (if appropriate) be reconstructed, typically by reading its data content from a store in the security unit.

Abstract: A master station including at least a token packet (Iso) management table in which the overall band of the bus is partitioned into certain bands, rewrites the token packet (Iso) management table according to the bandwidth required in Isochronous data transmission between stations to at least control transmission of token packets (Iso) and dynamically control the bandwidth.

Abstract: Access to a limited bandwidth switching network of an ATM (Asynchronous Transfer Mode) switch is scheduled using a reservation ring. In general, a limited bandwidth switching network is unable to generate all possible one-to-one input to output channel mappings in a single switch cycle. The limited bandwidth switching network includes one or more routing channels for routing at most B data packets each switch cycle between the input channels and output channels, where the number of data packets B is less than the aggregate output bandwidth that can be directed at the routing channels. Arbitration requests make two passes around the reservation ring each arbitration cycle. Output channel contention is settled during the first pass around the reservation ring. Contention for limited switching network bandwidth is settled during the second pass around the reservation ring.

Abstract: A communication interface 122 for a network having a plurality of nodes 100-108 and a communication link 124,126 (120) connected between predetermined ones of the nodes 100-108 which propagates bus data, includes a first shared communication circuit 128, to be connected in series with the link 124,126, which receives the bus data and passes shared data along the link 124,126, a second shared communication circuit 136,142, connected to one port 129 of the circuit 128, which receives the bus data from the link 124,126 and passes the shared data, and which receives the shared data and couples the shared data onto the link 126, a first unshared communication circuit 144,148, connected to the port 129 of the circuit 128, which receives the bus data from the link 126 and passes the unshared data, and which receives the shared data and couples the unshared data onto the link 126, a second unshared communication circuit 130,134, connected to another port 127 of the circuit 128, which receives the bus data from the li

Abstract: A computer local area network using the IEEE Token Ring Standard and Token Ring Adapters for connection to the physical layer and the backplane. The physical layer device and the MAC Device in the present invention are manufactured by different companies and belong to different chip sets. The MAC Device and the physical layer device are not designed to work with each other, and will not directly interface with each other. The present invention uses a programmable array logic (PAO) to modify signals between the physical layer device and the MAC Device so that proper operation can occur, especially with regard to the detection of valid data after frequency acquisition.

Abstract: A programmable direction control scheme for an efficiently wired array of like integrated circuit chips which is capable of producing a rightward or leftward sequence of designated interaction is described. The member chips are incorporated into a system by connecting their existing addressing, data, and clock pads onto a mutual bus. The chips are additionally chained together by their qualification pads so that they may be individually designated for interaction with the system, by way of sequential token passing. A direction control bit within a programmable configuration register is included on each member chip in lieu of a dedicated input. The configuration register is given free access irrespective of the designation status of its incorporating chip, and thus the direction control bits of all of the member chips of the array may be expediently programmed even when the elsewise process of sequencing through the chips would be paradoxically self obstructed by an initial directional chaos condition.

Abstract: A server, and a number of client stations interconnected by a token ring network, specifically an FDDI-II network. The FDDI-II ring is connected in a star-ring topology, with the server and the clients preferably connected to the network through a wiring closet, as is the usual practice for such a topology. The server has separate physical connections to the single FDDI-II ring with each physical connection to the ring providing access to a separate physical domain. This partitions the same ring into different physical domains, so that an increase in the total effective bandwidth of the network is achieved by the server reallocating the same isochronous bandwidth in each of the domains for reuse by the server. An allocation of bandwidth in an isochronous channel in one domain can be reused by the server in another physical domain.

Abstract: A method and system for providing arbitration within a ringlet-type interconnect of a computer system are described. By providing different arbitration values as part of out-of-band information and introducing asymmetry at a scrubber node, fair allocation of interconnect bandwidth is achieved. The number of arbitration values can be extended from a basic set to provide additional functionality to handle specialized traffic situations.

Abstract: Briefly, in accordance with one embodiment of the invention, a method of using a bypass buffer in a node coupled to a ringlet includes the steps of: writing a packet of binary digital signals on the ringlet into the bypass buffer; and retaining the packet of binary digital signals in the bypass buffer for a predetermined amount of time before transferring the packet to the ringlet.Briefly, in accordance with another embodiment, a node to be coupled to a ringlet includes: a transmit buffer and a receive buffer. The transmit and receive buffers are coupled in a configuration to transfer binary digital signals between the node and the ringlet via the transmit and receive buffers. The configuration further includes a bypass buffer to temporarily queue binary digital signals passing through the node. The bypass buffer is further coupled in the configuration to retain a packet of binary digital signals for a predetermined amount of time before transferring the packet to the ringlet.

Abstract: Arbitration apparatus is described for arbitrating between a number of jobs, for example for distributing message traffic over a data transmission network. The arbitration apparatus comprises an activity register containing a number of activity bits indicating which of a number of transmission jobs is currently active. The apparatus also includes a two-tier token ring arrangement comprising an outer ring and a number of inner rings. Each ring consists of a number of registers, holding a token which is passed cyclically around the ring. Each register has a bypass path which bypasses the register if a corresponding job or group of jobs is inactive. The positions of the tokens in the rings determines which job is to be scheduled next. Each ring also includes a keeper register for preserving the token if all the jobs are inactive.

Abstract: Access to a switching network of an ATM (Asynchronous Transfer Mode) switch is scheduled with a reservation ring that automatically determines the number of channels populating the switching network during a switch cycle. The reservation ring is a distributed arbiter that resolves conflicts arising among a plurality of input channels for access to a plurality of output channels of the switching network. Each input channel populating the switching network is coupled to an arbitration unit of the reservation ring. The arbitration units on the ring determine when an arbitration cycle is complete for each of the arbitration units populating the ring. This enables the number of channels populating the switching network to increase or decrease without having to reconfigure the reservation ring.

Abstract: An expandable local area hub network is provided by the present invention. The network comprises a plurality of hubs interconnected for direct communication. Each hub includes a plurality of ports for interfacing with remote stations, wherein the remote stations make requests that packets be transmitted on a memory coupled to the plurality of hubs. In use, one of the plurality of hubs is designated as a temporary controlling hub having controlling access to the memory bus to transmit packets on the memory bus. The temporary controlling hub relinquishing access to the memory bus when the temporary controlling hub has no requests to dispatch a packet on said memory bus.

Abstract: A computer network system repetitively distributes messages including uniquely identified blocks of real time data containing a current data image over a broadcast communications network to all real time stations for storage of each repetition of each entire block of data directly in station memory at a unique address space assigned to that uniquely identified block of data. The real time stations receive the blocks of data and alternatively receive other messages from the real time stations. The other messages have a recognized standard protocol, such as the TCP/IP or UDP/IP protocol of the Internet Protocol Suite.

Abstract: A hardware message transfer control unit designated as the Auxiliary Message Arbitrator Unit (AMA) manages message transfers and transfer protocols in a network of sending and receiving digital hardware modules. Flexibility of network expansion to include software emulated digital modules to the hardware modules is provided in RAM circuitry at the message transfer control unit.

Abstract: An end station port (2-6) for connection to a token passing communication system which connects a number of end station ports and in which the communications protocol under which the system operates permits more than one data frame to be transmitted by an end station within a predetermined token holding time comprises a transmit store/frame assembly unit (19) for preparing a data frame, having a length not exceeding a predetermined maximum size, for transmission; and control logic (20) for controlling the passage of data to and from the end station port for transmission on to and receipt from the communication system in use. The control logic (20) transmits a frame prepared by the frame assembly unit (19) when the token is held by the end station port.

Abstract: Traffic involved in maintaining a set of connection oriented sessions between end stations in a network is managed to optimize and reduce the polling traffic needed to maintain the connection oriented sessions across a common link between edge devices. At a first edge device, a member of a set of connection oriented sessions is selected as a polling session. Request polling traffic of that polling session is forwarded from a first edge device to the second edge device. All other polling traffic from other members of the set of connection oriented sessions is blocked at the first edge device. The set of connection oriented sessions is maintained in response to polling traffic of the selected polling session. A similar algorithm is executed at the second edge device to manage the traffic in both directions across the common link.

Abstract: A data transmission system for a vehicle includes a plurality of control systems installed on the vehicle, and a network bus connecting the plurality of control systems with each other for circulating a transmission right through the plurality of control systems to thereby perform transmission of a message between the plurality of control systems. According to a first aspect, each of the control systems starts transmitting data when it is detected that the transmission right is not generated or lost from the system, and continues transmitting the data when no collision of data transmitted from the present control system with data transmitted from the rest of the plurality of control systems, or when by mediation for avoiding the collision is detected, it is determined to continue data transmission.

Abstract: A communication system having communicating devices coupled to a closed loop bus substantially reduces interconnect distances and corresponding signal propagation delays between the devices. Particular devices possess switchable impedance elements that can be selectively actuated to produce an effective terminating impedance substantially at a midpoint position along the closed loop from the coupling point of a transmission device. In such an arrangement, the produced effective terminating impedance would cause the signal transmitted by the transmission device to propagate to a destination device substantially without signal degradation due to signal reflections.

Abstract: A method of connecting a new end station to a ring communication system for connecting a number of end stations is constituted by the steps of: i) sensing an attempt by the new end station to attach to the ring; ii) determining whether there is a single end station only existing on the ring; and, iiia) if it is determined that there is more than one end station on the ring, allowing the new end station to attach to the ring and maintaining the ring communication configuration; or b) if it is determined that there is a single end station only on the ring, breaking the ring configuration and setting up two separate communication paths between the new end station and the existing end station.

Abstract: In a token ring network a periodic recirculating frame having a plurality of information carrying slots and a header section is used for enabling a plurality of telephone stations to exchange information carrying signals. The header is provided with a token which can assume one of three states. In the first state FF, a telephone station wanting to make a call, changes the token to the second state 00 and inserts call establishment information in the header. A server station also connected in the ring detects the second state as a request to establish a connection from and to a station specified in the header. The server changes the token to the third state AA and inserts a slot assignment in the header. All stations receiving a frame with a token in the third state examine the header. The calling station implies confirmation of the requested connection and the called station is made aware of the call and the identity of the caller.

Abstract: An apparatus for accelerated Fiber Channel protocol handshaking and data exchange involves dividing a Fiber Channel arbitrated loop architecture up into a plurality of arbitrated subloops, each of which arbitrates locally using the same fundamentals as the Fiber Channel arbitration protocol but with some slight modifications which do not affect the compatibility of standard Fiber Channel nodes. Each subloop is coupled to a hub port which contains a state machine which does switching function and fill word generation to implement the accelerated protocol by using a plurality of switching, fill word generation and token passing rules. The state machine in each hub port is coupled to its local subloop and to its neighboring hub ports through a single TDMA bus which has timeslots dedicated to carrying broadcast loop and return loop traffic and control token traffic.

Abstract: A data frame which is transmitted from a transmitting station is provided with an individual response part (RS) having response bits (S1 to SN) corresponding to all stations on a network, so that the transmitting station initializes the individual response part (RS) in data transfer. Each receiving station outputs its own state to a prescribed position of the individual response part, and the transmitting station monitors the individual response part. Thus, it is possible to correctly confirm whether or not the data is normally transferred to those of the receiving stations which are to receive data.

Abstract: An advanced data server including an I/O ring coupled to at least one I/O access channel which provides data to the I/O ring or reads data out from the I/O ring; a disc array ring coupled to least two disc arrays which store therein data received from the disc array ring or retrieve therefrom data for receipt by the disc array ring, the disc array ring also being coupled to the I/O ring so that data can flow between those rings; and a server controller coupled to the I/O ring and the disc array ring for controlling the operations thereof. The I/O ring includes a first ring controller which controls receipt of data from the I/O access channel and transfer of that data to the disc array ring, or receipt of data from the disc array ring and transfer of that data to the I/O access channel.