Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A method of communicating frames of management information includes loading a frame of management information from one of a plurality of stations into a respective one of a plurality of buffers. Whether the frame contains more than a predetermined number of bytes is determined. If an end of the frame is loaded into the respective one of the buffers, then a frame presence flag associated with said one of the plurality of stations is set. A request signal is transmitted to a station management module if the frame contains more than the predetermined number of bytes or if the buffer already contains management information associated with a previously loaded frame. The plurality of stations is polled to determine whether respective frame presence flags have been set.

Abstract: A switching fabric for transmitting digital data from a plurality of sources to a plurality of destinations is described. The switching fabric includes a plurality of input ports, a plurality of output ports and a plurality of switching sections. Each of the input ports receives data frames and partitions the received data payload of at least some of the frames into a plurality of associated data cells. Each of the output ports are coupled to at least one destination associated with the headers of the data frames. Each of the switching sections may be coupled to each of the input ports and each of the output ports for transmitting each of selected ones of the data cells from the at least one input port to one or more of the coupled output ports.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A method of communicating frames of management information includes loading a frame of management information from one of a plurality of stations into a respective one of a plurality of buffers. Whether the frame contains more than a predetermined number of bytes is determined. If an end of the frame is loaded into the respective one of the buffers, then a frame presence flag associated with said one of the plurality of stations is set. A request signal is transmitted to a station management module if the frame contains more than the predetermined number of bytes or if the buffer already contains management information associated with a previously loaded frame. The plurality of stations is polled to determine whether respective frame presence flags have been set.

Abstract: A system and method of transmitting data frames between a plurality of input ports to a plurality of output ports is described. The input ports segment portions of the received data frames to provide smaller data cells which are individually transmitted to an output port associated with a destination of the segmented data frame. Based upon information provided in the data cells received at the output port, the output port determines the ordinal positions of the received data cells within the segmented data frame and reassembles the data frame which was segmented at the input port. The output port then forwards the reassembled frame toward the associated destination.

Abstract: A method and apparatus for coupling a signal from one node to another node prepares a signal for transmission, performs error checking on such signal while simultaneously transferring such signal within a transmitting node, transmits the signal from the transmitting node, receives and formats the signal at a receiving node, including an identifying portion and a data portion, and directly stores the data portion in memory that is directly accessible by a user process executing in the receiving node while simultaneously performing error checking.

Abstract: Systems and methods for providing graceful insertion of a station or tree into a ring type network. According to one aspect of the invention, graceful insertion is achieved after coupling a tree to a tree link of a master port by switching the tree into a local ring, holding the local ring, and awaiting a token on the network ring. After a token is received on the network ring, the tree is switched from the local ring to the network ring. Monitoring ring status in hardware provides the responsiveness necessary which software graceful insertion typically cannot provide.

Abstract: A ring latency timer provides a station attached to a token ring network with the capability of obtaining an accurate latency measurement of the ring to which it is attached. An internal hardware register, which may be read via the processor control bus interface, contains the latest ring latency measurement. A latency interrupt bit, when cleared, enables the latency measurement function. A subsequent interrupt which causes the latency interrupt bit to be set by the chip signals the completion of the latency measurement and the function is once again disabled. The latency register holds the latency information until the interrupt bit is cleared by the processor.

Abstract: The present invention provides asynchronous priority select logic for allowinig an individual station on a token ring network to hold a token for asynchronous transmission only for a specified maximum time period. The asynchronous priority select logic comprises a token rotation timer for timing token rotations on the ring from arrival to arrival. A token holding timer limits the amount of ring bandwidth used by the station for asynchronous transmission after the token is captured by the station. Select circuitry responsive to the value of the token rotation timer determines if the captured token is still usable for transmission by determining if the token rotation timer value is less than a preselected asynchronous threshold value. The select logic includes means for generating a selected asynchronous threshold value having a first bit length. The selected asynchronous threshold value is then expanded to a second bit length corresponding to the bit length of the token holding timer value.

Abstract: Disclosed is a bidding method for regenerating a lost write token in a token controlled loop communications network. In response to a station on the loop detecting the loss of the write token, the station will generate a unique recovery token specifying as the destination address that station's individual address and transmit the generated recovery token onto the loop. Stations receiving the recovery token will examine the recovery token's destination address and based on a bidding method, will either pass the recovery token on unaltered or substitute the receiving station's individual address if the recovery token's destination address is not equal to the receiving station's individual address. When a receiving station's individual address matches that specified in the recovery token, that station wins the bid and generates a new write token.The method disclosed can also be used to generate a write token when the network is initialized.

Abstract: A method of allocating available bandwidth between stations configured in a write token controlled loop communications network. When a station desires to reserve additional bandwidth to itself, it captures the write token and transmits a bandwidth allocation token which includes a field indicating the originating station's amount of currently reserved bandwidth. Each station on the loop adds to the field the amount of its currently reserved bandwidth. When the allocation token arrives back at the originating station, the write token is regenerated and transmitted. If the total amount of currently reserved bandwidth indicated in the allocation token plus the desired additional bandwidth sought to be reserved is less than the allocatable bandwidth, then the reservation is granted. The additional bandwidth desired is then added to the total reserved by the originating station.

Abstract: Disclosed is a timed token protocol which may be implemented on a physical or logical ring, the ring interconnecting a plurality of stations to form a local area network. Each station on the ring may be assigned one or more of three priority levels, the priority levels corresponding to the type of service required by a station. The highest priority level (Class 1) corresponds to applications requiring a guarantee of bandwidth (e.g., digital voice), the second priority level (Class 2) corresponds to applications requiring minimum throughput, but no absolute guarantee of bandwidth (e.g., interactive data communications between terminals and hosts), and the lowest priority level (Class 3) corresponds to applications where no minimum throughput is required (e.g., batch information transfer).Class 1 stations share a pool of bandwidth, portions of which may be allocated to each Class 1 station in accordance with a bandwidth allocation procedure.

Abstract: Disclosed is a timed token protocol which may be implemented either on a physical loop or a logical loop superimposed on a physical bus, the loop interconnecting a plurality of stations to form a network. Each station on the network may be of the same priority level, or may be of one or both of two priority levels.In the single priority level network, a station can transmit information upon the receipt of a write token if the time since the previous receipt of a write token is less than a preset amount of time, the difference between the observed write token rotation time and the preset amount of time representing the amount of unused capacity on the previous rotation of the write token.

Abstract: Disclosed is a bidding method for regenerating a lost write token in a token controlled loop communications network. In response to a station on the loop detecting the loss of the write token, the station will generate a unique recovery token specifying as the destination address that station's individual address and transmit the generated recovery token onto the loop. Stations receiving the recovery token will examine the recovery token's destination address and based on a bidding method, will either pass the recovery token on unaltered or substitute the receiving station's individual address if the recovery token's destination address is not equal to the receiving station's individual address. When a receiving station's individual address matches that specified in the recovery token, that station wins the bid and generates a new write token.The method disclosed can also be used to generate a write token when the network is initialized.