Abstract: A method and apparatus for enhancing existing caching systems to better support streaming media over the Internet and other public network system are disclosed herein. By using helpers inside the network, which operate as caching and streaming agents, existing caching techniques are enhanced to better support streaming media over the Internet. The helpers serve to implement several methods specifically designed to support streaming media, including proxy caching, client request aggregation which describes the use of memory and disk resources at the helpers, and data transfer rate control to reduce start-up latency. The method and apparatus advantageously reduces server and network loads by employing the above methods to overcome arrival time and range heterogeneity in client requests thereby improving the quality perceived by end users.

Abstract: A method for providing peer-to-peer virtual private network (P2P-VPN) services over a network. The method includes identifying subnet and host addresses for each user device requesting participation in a virtual private network (VPN) session. Once the subnet and host addresses are identified, a virtual private host (VPH) is initiated for each user device, where each VPH communicates with each user device via a respective tunnel through the network, thereby enabling secure communications between the user devices.

Abstract: The present invention addresses the shortcoming of the prior art by providing a network support mechanism that is transparent to real-time multi-user distributed applications. In particular, the proposed invention is well suited for the type of online multi-player games in which a fair order of player actions is critical to the outcome. Without fairness support, remote players often receive much delayed data to act on, and their actions cannot compete in time with other players. The present invention proposes a network support mechanism, called Sync-VPN, for real time multi-user distributed applications such as multi-player online games. The approach assumes a client/server application model, where the server is responsible for coordinating state updates based on action messages sent by the clients. The approach addresses three desired features: predictable packet service, state update fairness, and player action fairness.

Abstract: In a communications network deploying caches or proxy servers, an improvement is described utilizing a separate cache to aggregate requests and responses according to a protocol between the deployed cache and an application server.

Abstract: A new architecture and operational techniques for supporting high quality live and on-demand streaming multimedia on a data network. By using Helper machines inside the network as data forwarding, caching, and buffering agents, and by forming meshes among Helper machines, advantages of homogeneous, synchronous multicast transmission and of heterogeneous, asynchronous reception are achieved. The architecture provides essentially transparently support to the receivers for near-zero start-up latency, improved playback quality, improved CR-like operations. These are achieved while reducing network and server load compared to today's multimedia networking techniques.

Abstract: A system and method of cache replacement for streaming multimedia is provided. A network system includes a content provider connected to local service providers via an interactive distribution network, such as the Internet. The local service providers facilitate delivery of the content from the content provider to multiple subscribers. For each of the data blocks which make up the multimedia stream requested by a subscriber, the local service provider receiving the request determines whether the request can be serviced locally or whether the requested data blocks must be retrieved from the content provider. In the case where the portion of the requested stream must be retrieved from the content provider, the local service provider attempts to cache the requested blocks in its local cache in addition to streaming the data blocks to the requesting subscriber.

Abstract: A data streaming transmission method and system is disclosed having a network server connected to client device through a communication network with one or more of caching servers. The network server has a data streaming application and a memory for storing data. A series of connections, each using a data streaming arrangement, is formed in the path between the source network and client device by the caching servers. Each caching server can absorb network congestion in its downstream connection by utilizing an expandable buffer for storing additional segments of the streamed data and varying the transmission data rate in the down stream connection.

Abstract: A caching device comprises a disk cache that stores web objects. Each web object stored in disk cache is stored in contiguous storage space locations in the disk cache. Each pair of temporally successive web objects stored in the disk cache are stored in substantially sequential storage space locations in the disk cache.

Abstract: A new architecture and operational techniques for supporting high quality live and on-demand streaming multimedia on a data network. By using Helper machines inside the network as data forwarding, caching, and buffering agents, and by forming meshes among Helper machines, advantages of homogeneous, synchronous multicast transmission and of heterogeneous, asynchronous reception are achieved. The architecture provides essentially transparently support to the receivers for near-zero start-up latency, improved playback quality, improved CR-like operations. These are achieved while reducing network and server load compared to today's multimedia networking techniques.

Abstract: In an arrangement that employs a push-pull paradigm, information that is to be communicated to clients is broadcast, or multicast, to cache servers, wherein the information is cached in preparation for its being pulled by clients. By pushing information to points close to the clients, both source overload and network overload are avoided. The pushed information in the disclosed approach is transmitted over Internet links, or over other communication channels, such as cable and radio systems. In operation, clients subscribe to specific services of the provider, an association is established between the subscribing client and a cache server, and the server informs the network that it should be included among the destinations to which information from the provider is transmitted. When information is subsequently transmitted by the provider and received by the cache servers, it is stored in the cache server in preparation for its being pulled by the clients, as desired and when desired.

Abstract: Client's (106-1-106-N, 107-1-107-M) on local area networks (102, 103) making requests to hot sites, which are connected on a wide area network (100) such as the Internet, are redirected through one of a possible plurality of different redirectors (101, 103) to one of a possible plurality of caching servers (S1, S2, S3), which each have responsibility for mapping one or more of the hot sites. Each request is probabilistically directed by one of the redirectors to one of the caching servers that map the requested hot site in accordance with weights that are determined for that redirector-hot site pair so as to minimize the average delay that all client requests across the network will encounter in making requests to all the cached hot sites.

Abstract: Layered Video Multicast with Retransmissions (LVMR) is a system for distributing video content using layered coding over the Internet. The two key contributions of the system are (1) improving the quality of reception within each layer by retransmitting lost packets given an upper bound on recovery time and applying an adaptive playback point scheme to help achieve more successful retransmission, and (2) adapting to network congestion and heterogeneity using a hierarchical rate control mechanism. A hierarchical rate control system and method is disclosed for regulating the flow of video information in a network by establishing subnet agents for each subnet, and by establishing intermediate agents for each domain. The subnet agents gather information concerning add-layer experiments conducted by receivers in a subnet, and the information is provided to intermediate agents of the domains for regulating data traffic.

Abstract: A system and method for multicast conferencing and online discussion groups using a periodically determined a close-to-optimal Steiner spanning tree. Both the system and method are suitable for stationary and/or mobile group members.

Abstract: A real-time, layered video multicast transmission system for transmitting video frames as a stream of encoded video data packets from a sender to one or more receivers over a network, comprises a device for generating one or more independent layers of video substreams out of the encoded video stream, each of the one or more receivers capable of subscribing to one or more layers of the independent video substreams; a device for transporting each of the independent video substreams over the network, the transporting device transporting each substream as an independent flow capable of being received by each of the one or more receivers; a device for monitoring congestive state of the network and the receiver to determine receiver's capability for receiving each of the video substream layer; and a controller provided to enable the receivers to select one or more of the independent video streams in accordance with the congestive state of the receiver.

Abstract: Real-time hardware primitives are added to packet switches to provide efficient support for inward multicasting. The lookup table used for routing is extended by adding additional opcode and operand fields into the routing table and by including ALU circuitry to process these fields and corresponding fields in the arriving cells. Memory word widths can be extended with minimal additional chip count and the ALU can be a small addition in a header processing VLSI, thereby giving only a modest increase in complexity. By including real-time processing in the switch it is possible to solve the ACK implosion problem associated with high-speed reliable multicasting transport protocols. By keeping the primitives as general as possible, other applications can benefit as well from these real-time primitives.

Abstract: A protocol that provides assurance of consistent replication of objects from a server to caching servers, for example, over data communication networks such as the Internet. It is an application-layer protocol which guarantees delivery of objects such as files. This protocol insures that objects sent by a source machine such as a server to any number of destination machines such as caching servers actually arrive at the intended caching servers even when the caching servers are temporarily unavailable, for example, due to failure or network partition.

Abstract: A multicasting method transmits data segments, including one or more data packets, over an established global multicast tree from a Sender S to a dynamically changing set of receivers, including at least one unknown Receiver R. In response to a data segment transmission, the Sender S receives a first status signal from the at least one unknown Receiver R (and/or any known Designated Receivers DRs) indicating the addition of and packet reception status of the unknown Receiver R (and/or any known Designated Receivers DRs) which has joined the multicast. In response to the status signals, the Sender S retransmits to the unknown Receiver R (and/or any known Designated Receivers DRs) those packets not received thereat. In this manner the unknown Receiver R (and/or any known Designated Receivers DRs) is added to the multicast session and retransmissions thereto are handled in the same manner as other receivers connected to the multicast session.

Abstract: Methods and systems for controlling data transfer operations during a communication session between a transmitter and at least one receiver provide that data packets which have been stored at the receiver memory before a disconnect occurred remain stored in therein in the presence of the disconnect to avoid the need for retransmitting data packets upon re-establishment of a communication link. Data representative of those data packets already stored at the receiver memory is maintained for purposes of synchronizing data packet transmission from the transmitter for completing data file transfer. Data control instructions for implementing storage of data packets and tracking the progression of data packet transmissions when a disconnect occurs may suitably included in an existing protocol layer of a communication system or as an additional protocol layer added to the operating system of the communication system.

Abstract: The inventive methods employ symmetric encryption with first and second keys to provide secure access to information accessible to be shared among a dynamically changing set of authorized users on a network having a server. A single copy of the information, encrypted with the first key of the server, is stored in a location accessible to all network users. The second key is a private key of an authorized user and is used by the server to encrypt the first key. The encrypted first key is then stored by the server at a storage location accessible by the authorized user. The user accesses the storage location, obtains the encrypted first key, and uses his private second key to decrypt and thereby recover the first key. The user then decrypts the stored information using the recovered first key.

Abstract: A method and apparatus for generating a conformance test data sequence of minimal length to verify that a device conforms to a protocol entity which can be characterized by a simplified extended finite state machine. The method generates an expanded directed graph of the protocol wherein each state is represented by a state vertex and a dummy vertex which are connected to other similar state and dummy vertices by directed edges in a configuration corresponding to the operation of the machine. The directed edges are then assigned traversal numbers corresponding to the minimum number of times a respective directed edge need be traversed in order to test values in a predetermined test data set. The traversal numbers of the expanded directed graph are balanced to form a symmetric expanded directed graph. An Euler tour and a corresponding unique input-output sequence of the last state of the Euler tour are generated to form the conformance test data sequence.