Abstract: A method for increasing the storage capacity of a video server which utilizes an array of disks is disclosed. The server is operated so that the continuity of a plurality of bit streams is maintained. The inventive method has advantageous characteristics with respect to storage capacity, streaming capacity, start-up latency of new streams, amount of required buffer capacity, scalability, reliability and multiple bit rates.

Abstract: In a live multicast in a LAN environment, audio and video streams are transmitted from a source station to a plurality of receiving stations. A technique is disclosed for synchronizing the audio decoder clock at each receiving station with the source station. A technique is also disclosed for synchronizing the audio and video data streams received at each receiving station.

Abstract: The present invention provides a method for achieving alignment of the header fields of a specific layer, such as the transport layer header fields, at a receiving host. The receiving host determines a number of padding bytes that need to be added to the transport layer header for the fields to be properly aligned in the memory of the receiving host. This number is determined dynamically for each connection because different connections require different numbers of padding bytes. The number of padding bytes for a connection is determined by the receiving host from the first packet received for a particular connection. Specifically, the receiving host examines this first packet and determines the position of the first byte of the transport layer protocol header, and therefore, the number of padding bytes required to achieve 32-bit (or 64 bit) alignment. The receiving host communicates the number of padding bytes to the transmitting host.

Abstract: A method is disclosed for interfacing a video storage system, such as a disk array, and a video stream application executing on a computer network or stand-alone system. The interface provides a method for storing video stream data by allocating storage space in units of stripes and for accessing the data in units of fixed length segments, wherein each stripe includes one fixed length segment from each disk of the array. The interface also queues submitted I/O transaction requests so that I/O transactions requested on a current I/O cycle i are not performed until the next I/O cycle i+1. The I/O transactions thus queued are performed in an order which permits a maximum number of I/O transactions to be performed each I/O cycle, regardless of the order in which they were submitted. In addition, the interface also queues the submitted I/O transaction requests so that the completion of an I/O transaction on a current I/O cycle i is not returned until the next I/O cycle i+1.

Abstract: A method for operating a disk storage system, comprising a disk and forming part of a communications network, simultaneously maintains the continuity of a plurality of data streams. Typically, each stream transfers video data to or from the disk storage system. Illustratively, each of the data streams is produced in the network at a rate of W.sub.base bits/sec and consumed by the disk storage system or produced by said disk storage system and consumed in the network at a rate of W.sub.base bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/W.sub.base, wherein in each I/O transaction a segment of S bits is retrieved from or stored in the disk. The number of streams whose continuity can be maintained in this manner is limited by the number of I/O's which can be performed in a cycle of duration S/W.sub.base. More generally, when a stream has a bit rate (A/B)W.sub.

Abstract: A method for operating a disk storage system, comprising a disk and forming part of a communications network, simultaneously maintains the continuity of a plurality of data streams. Typically, each stream transfers video data to or from the disk storage system. Illustratively, each of the data streams is produced in the network at a rate of W.sub.base bits/sec and consumed by the disk storage system or produced by said disk storage system and consumed in the network at a rate of W.sub.base bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/W.sub.base, wherein in each I/O transaction a segment of S bits is retrieved from or stored in the disk. The number of streams whose continuity can be maintained in this manner is limited by the number of I/O's which can be performed in a cycle of duration S/W.sub.base. More generally, when a stream has a bit rate (A/B)W.sub.

Abstract: A method for increasing the storage capacity of a video server which utilizes an array of disks is disclosed. The server is operated so that the continuity of a plurality of bit streams is maintained. The inventive method has advantageous characteristics with respect to storage capacity, streaming capacity, start-up latency of new streams, amount of required buffer capacity, scalability, reliability and multiple bit rates.

Abstract: A method for operating a disk storage system, comprising a disk and forming part of a communications network, simultaneously maintains the continuity of a plurality of data streams. Typically, each stream transfers video data to or from the disk storage system. Illustratively, each of the data streams is produced in the network at a rate of W.sub.base bits/sec and consumed by the disk storage system or produced by said disk storage system and consumed in the network at a rate of W.sub.base bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/W.sub.base, wherein in each I/O transaction a segment of S bits is retrieved from or stored in the disk. The number of streams whose continuity can be maintained in this manner is limited by the number of I/O's which can be performed in a cycle of duration S/W.sub.base. More generally, when a stream has a bit rate (A/B)W.sub.

Abstract: Multicast video services are provided in a network having a star topology. The network illustratively compromises a switched hub having a shared transmission medium and a plurality of ports. An Ethernet segment is connected to each port. Client stations belonging to the Ethernet segments communicate to the associated ports information identifying the particular multicasts they wish to receive. This is accomplished by sending special packets (mask update packets) from the client stations to the ports. Only multicast video data packets belonging to multicasts identified in the update packets are transmitted by the ports on the associated Ethernet segments.

Abstract: A method for operating a disk storage system, comprising a disk and forming part of a communications network, simultaneously maintains the continuity of a plurality of data streams. Typically, each stream transfers video data to or from the disk storage system. Illustratively, each of the data streams is produced in the network at a rate of W.sub.base bits/sec and consumed by the disk storage system or produced by said disk storage system and consumed in the network at a rate of W.sub.base bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/W.sub.base, wherein in each I/O transaction a segment of S bits is retrieved from or stored in the disk. The number of streams whose continuity can be maintained in this manner is limited by the number of I/O's which can be performed in a cycle of duration S/W.sub.base. More generally, when a stream has a bit rate (A/B)W.sub.

Abstract: A local area network for supporting video applications comprises a transmission medium, one or more data file servers connected to the transmission medium for supporting data applications in the local area network, a dedicated video server for supporting video applications in the local area network and one or more clients connected to the local area network. The server includes software for managing multiple simultaneous video streams transmitted across the LAN. The client includes software for accessing the dedicated video server across the LAN to transmit video to the server or receive video from the server.

Abstract: In a local area network segment, the bandwidth in the channel between a network interface device, e.g., a port, switching hub, router, bridge or server, and one or more associated station is shared as follows. At the network interface device, a variable is maintained which stores information relating to the success or failure of transmission of packets in the channel. If the channel is sensed idle, the network interface device transmits the packet with probability 1. If the channel is sensed busy, the network interface device senses the channel for an end-of-carrier signal and, thereafter, waits a period of time equal to the interframe gap g. In addition, after an additional delay period .zeta., the network interface device reattempts to transmit the packet in the channel. If the variable maintained by the network interface device is less than a certain limit, the delay .zeta. is selected according to a first basic bandwidth allocation protocol.

Abstract: A station is provided which is connected to a network segment via a shared transmission medium. The station includes one or more protocol stacks for processing each type of data packet which the station may transmit to or receive from the shared transmission medium. A queue is associated with each protocol for storing corresponding data packets. The station is also provided with a media access controller, which is unable to differentiate among the different types of data packets. The media access controller is provided for enabling data packets of the different types stored in the queues to access the transmission medium with arbitrary priority. A throttler is also provided for controlling the submission of data packets from the queues to the media access controller, depending on the type of the data packets, to provide an appropriate amount of bandwidth in, and to limit the access delay of, a particular type of data packets in the shared transmission medium.

Abstract: A process for fairly allocating resources in a multiport packet switch is disclosed. Each port is connected to a station and comprises a transmit FIFO buffer and a receive FIFO buffer. The ports are connected by a broadcast transmission medium. A transmit buffer of a specific port gains access to the transmission medium when the port possesses a token which is passed from port to port in a round-robin fashion. When a port recognizes that a transmitted packet is addressed to it, the port uses a local processor to determine whether or not to accept the packet. The determination is based on (1) information in the packet header, e.g., priority and address of the transmitting port, (2) the status of the receive buffer (full or not), and (3) other locally recorded information regarding past history of the acceptance or rejection of packets from particular ports and of particular priority classes needed to achieve fairness among packets of the same class and priority among different classes.