Abstract: A technique for managing session setup for video on demand sessions involves caching information related to session setup for a session manager and then utilizing the cached information to setup a video on demand session for a client in response to a session setup request that is received from the client. Because information related to session setup is cached for the session manager, the session manager can utilize the information to establish a session without having to exchange messages with other video on demand elements, in particular other servers in the video on demand network. Reducing or eliminating the number of messages exchanged between video on demand elements enables video on demand sessions to be quickly and efficiently setup.

Abstract: A technique for streaming digital video content to a client involves providing a new stream of digital video content to the client using forward error correction (FEC) for a limited initial period and then ending the use of FEC after the limited initial period has ended. In an embodiment, during the limited initial period, the digital video content is provided to the client at a rate that is slightly higher than the playout rate in order to allow a client buffer to accumulate digital video content. FEC continues to be used until the client buffer is sufficiently populated such that lost or damaged frames can be retransmitted to the client before the corresponding digital video content is needed for playout. Once the client buffer is sufficiently populated, FEC is ended and retransmission is used to maintain the quality of the streamed digital video content.

Abstract: A technique for managing the streaming of digital video content involves providing a unicast stream to a client in response to the playout status of the unicast stream at the client. In particular, a unicast stream is provided to a client based on whether or not the unicast stream is intended for real-time playout at the client. In order to preserve valuable network resources, if the client does not intend the unicast stream for real-time playout, the unicast stream is not provided to the client. Network resources can also be conserved by utilizing one session between a stream server and a client to support more than one active unicast stream between the stream server and the client in the case where at least one of the active unicast streams is not intended for real-time playout at the client.

Abstract: A technique for managing the streaming of digital video content to multiple clients involves identifying an attribute of a content element that is streamed to a client and selecting a protection mechanism for the content element as a function of the attribute, wherein the protection mechanism enables streaming of the content element to the clients in the event of a resource failure. In an example, the identified attribute is an indication of the popularity of the content element (e.g., as measured by the number of active streams), such that the protection mechanism is selected as a function of the popularity of the content element. In an embodiment, protection mechanisms that offer a higher level of protection are selected for the more popular content elements and protection mechanisms that offer a lower level of protection are selected for the less popular content elements.

Abstract: A technique for streaming digital video content to multiple clients involves establishing a logical group of IP-connected stream servers, generating state information at multiple stream servers within the logical group, sharing the state information amongst stream servers in the logical group, and using the shared state information to respond to resource failures within the logical group. By sharing state information within the logical group of stream servers, stream servers with the shared state information can quickly take over the active streams from a failed stream server within the logical group. The quick transition of responsibility from one stream server to another enables the streaming network to provide continuous streaming of digital video content to the viewer without interruption.

Abstract: A technique for transitioning streamed digital video content between stream servers involves identifying a transition identifier that indicates a point at which streaming of the digital video content transitions from a first stream server to a second stream server and then transitioning the streaming from the first stream server the second stream server at a point in the digital video content that corresponds to the transition identifier. For example, the first stream server stops streaming the digital video content at a point in the digital video content that corresponds to the transition identifier and the second stream server starts streaming the digital video content at a point in the digital video content that corresponds to the transition identifier.

Abstract: Switching a client from unicasting back to multicasting involves simultaneously providing the digital video content to the client via unicasting and multicasting until the client has buffered duplicate frames (i.e., frames that contain the same digital video content). Once the client has buffered duplicate frames, the client can transition from playing out of a buffer that holds frames received via unicasting to playing out of a buffer that holds frames received via multicasting without skipping a frame. Once the transition back to multicasting is complete, unicasting is terminated and any frames remaining in the unicast buffer are flushed.

Abstract: In a digital video network that is capable of distributing digital video content to a client via multicasting and unicasting, servicing a channel change request from a client involves switching from providing the digital video content to the client via multicasting to providing the digital video content to the client via unicasting and continuing to provide digital video content to the client via unicasting until a pre-established condition is met. Continuing to provide digital video content to the client via unicasting until a pre-established condition is met allows the network to opportunistically switch the client from unicasting back to multicasting.

Abstract: A technique for managing the streaming of digital video content to multiple clients involves identifying an attribute of a content element that is streamed to a client and selecting a protection mechanism for the content element as a function of the attribute, wherein the protection mechanism enables streaming of the content element to the clients in the event of a resource failure. In an example, the identified attribute is an indication of the popularity of the content element (e.g., as measured by the number of active streams), such that the protection mechanism is selected as a function of the popularity of the content element. In an embodiment, protection mechanisms that offer a higher level of protection are selected for the more popular content elements and protection mechanisms that offer a lower level of protection are selected for the less popular content elements.

Abstract: Switching a client from unicasting back to multicasting involves accumulating enough digital video content at the client to bridge the time it takes to transition from receiving the digital video content via unicasting to receiving the digital video content via multicasting. Digital video content is accumulated at the client by temporarily increasing the stream rate of the unicast stream above the playout rate. While the digital video content is being streamed at the increased rate, the amount of digital video content stored in the client's stream buffer grows. The stream rate is held at the increased rate until the client accumulates enough frames in its buffer to be able to bridge the time it takes to transition from receiving the digital video content via unicasting to receiving the digital video content via multicasting.

Abstract: A technique for managing the streaming of digital video content to multiple clients involves identifying an attribute of a content element that is streamed to a client and selecting a protection mechanism for the content element as a function of the attribute, wherein the protection mechanism enables streaming of the content element to the clients in the event of a resource failure. In an example, the identified attribute is an indication of the popularity of the content element (e.g., as measured by the number of active streams), such that the protection mechanism is selected as a function of the popularity of the content element. In an embodiment, protection mechanisms that offer a higher level of protection are selected for the more popular content elements and protection mechanisms that offer a lower level of protection are selected for the less popular content elements.

Abstract: A technique for transitioning streamed digital video content between stream servers involves identifying a transition identifier that indicates a point at which streaming of the digital video content transitions from a first stream server to a second stream server and then transitioning the streaming from the first stream server the second stream server at a point in the digital video content that corresponds to the transition identifier. For example, the first stream server stops streaming the digital video content at a point in the digital video content that corresponds to the transition identifier and the second stream server starts streaming the digital video content at a point in the digital video content that corresponds to the transition identifier.

Abstract: A technique for streaming digital video content to a client involves providing a new stream of digital video content to the client using forward error correction (FEC) for a limited initial period and then ending the use of FEC after the limited initial period has ended. In an embodiment, during the limited initial period, the digital video content is provided to the client at a rate that is slightly higher than the playout rate in order to allow a client buffer to accumulate digital video content. FEC continues to be used until the client buffer is sufficiently populated such that lost or damaged frames can be retransmitted to the client before the corresponding digital video content is needed for playout. Once the client buffer is sufficiently populated, FEC is ended and retransmission is used to maintain the quality of the streamed digital video content.

Abstract: Network traffic management is achieved based on automatically setting up a plurality of virtual networks (VNETs) within a single large virtual LAN. Multicast/broadcast traffic is confined to the VNET of the source, without imposing constraints on layer two addressing within the virtual LAN. VNETs are domains of users of a virtual LAN which include members of logical networks defined at layer three or higher. One method includes transferring a multi-destination packet originating from a particular node in the virtual LAN by tunnelling across a connectionless backbone network to a virtual net server. The virtual net server translates the multi-destination packet to a plurality of tunneled messages identifying nodes authorized to receive multi-destination packets from members of the particular VNET which originated the packet. The tunneled messages are then forwarded from the virtual net server to the authorized nodes.

Abstract: A method for improving network security in a network that includes a star configured interconnection device such as a repeater, a bridge or a switch, that has a plurality of ports adapted for connection to respective MAC layer devices includes storing authentication data in the star configured interconnection device that maps MAC addresses of end stations in the network to particular ports on the star configured interconnection device. Upon receiving a packet on a particular port, the process involves determining whether the packet carries a source address which the authentication data maps to the particular port. If the packet carries a source address which the authentication data maps to the particular port, then the packet is accepted. If the packet does not carry a source MAC address which the authentication maps to the port, then an authentication protocol is executed on the port to determine whether the MAC address originates from an authorized sender according to the authentication protocol.

Abstract: Network traffic management is achieved based on automatically setting up a plurality of virtual networks (VNETs) within a single large virtual LAN. Multicast/broadcast traffic is confined to the VNET of the source, without imposing constraints on layer two addressing within the virtual LAN. VNETs are domains of users of a virtual LAN which include members of logical networks defined at layer three or higher. One method includes transferring a multi-destination packet originating from a particular node in the virtual LAN by tunnelling across a connectionless backbone network to a virtual net server. The virtual net server translates the multi-destination packet to a plurality of tunneled messages identifying nodes authorized to receive multi-destination packets from members of the particular VNET which originated the packet. The tunneled messages are then forwarded from the virtual net server to the authorized nodes.

Abstract: A method is provided for sending data from a data source executing a network protocol such as the TCP/IP protocol stack, which includes a process for generating headers for packets according to the network protocol. The method includes sending such data on a network through a smart network interface. The network protocol defines a datagram in the data source, including generating a header template and supplying a data payload. The datagram is supplied to the network interface. At the network interface, a plurality of packets of data are generated from the datagram. The plurality of packets include respective headers, such as TCP/IP headers, based on the header template, and include respective segments of the data payload. The network interface supports packets having a pre-specified length, and the data payload is greater than the pre-specified length, such as two to forty times larger or more.

Abstract: A scalable CSMA/CD repeater is based on polling and collision resolution logic, and slot time and interframe gap negotiation logic controlled by the repeater itself. The repeater based polling and collision resolution provides central control of the backoff and retry algorithm of each connected MAC unit. Thus, the MAC unit does not rely on random backoff mechanisms that significantly degrade performance of prior art systems. Furthermore, the retry by a MAC unit after a collision is managed by commands received from the collision resolution logic in the repeater. The repeater based collision resolution logic ensures that all ports involved in a collision have a fair opportunity to forward a packet without being blocked before enabling all the ports in the network to freely compete again.

Abstract: Early initiation of transmission of data in a network interface that includes a dedicated transmit buffer is provided in a system which includes logic for transferring frames of data composed by the host computer into the transmit buffer. The amount of data of a frame which is downloaded by the host to the transmit buffer is monitored to make a threshold determination of an amount of data of the frame resident in the transmit data buffer. The network interface controller includes logic for initiating transmission of the frame when the threshold determination indicates that a sufficient portion of the frame is resident in the transmit buffer, and prior to transfer of all of the data of the frame into the transmit buffer. The monitoring logic includes a threshold store, which is programmable by the host computer for storing a threshold value. Thus, the threshold value may be set by the host system to optimize performance in a given setting.

Abstract: A method allows a designer to implement software for a wide variety of variant host architectures, without excessive usage of host memory, nor sacrificing the capabilities of high end versions of the variant architectures available. The method is based on providing an initialization module of the software to host memory. A portion of the initialization module determines the host architecture. Based on the determined host architecture, the unneeded portions of the initialization module are freed, and the needed portions are relocated into a contiguous memory space to minimize host memory usage. Any location dependent entries in the needed portions of the program are then updated based on the relocation. The initialization module includes a plurality of code blocks, each of which is optimized to a particular variant architecture. When the variant architecture of the host is identified, those code blocks which are optimized to the identified host are selected and the other code blocks are freed.