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 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 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 managing video content for a video on demand (VOD) session involves replacing trick mode content with pre-defined replacement content when a trick mode command is executed. The replacement content is displayed in a clear and intelligible manner (e.g., at normal speed) even though a trick mode command, such as fast forward, reverse, or fast reverse, has been executed. In an embodiment, the replacement content is a replacement advertisement, which may be in the form of a moving image that is displayed as normal speed or a fixed image.

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: 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 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 managing session setup requests involves operating in a normal mode when the arrival rate of session setup requests is below a normal transition boundary, and transitioning from the normal mode to a coalescing mode when the arrival rate of session setup requests rises above a coalescing transition boundary. In the normal mode, the session manager processes each of the session setup requests individually; whereas in the coalescing mode, multiple session setup requests are batched and processed collectively. The session manager may be transitioned from the normal mode to the coalescing mode when the session setup request arrival rate rises above a coalescing transition boundary, and the session manager may be transitioned from the coalescing mode to the normal mode when the session setup request arrival rate falls below a normal transition boundary.

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: In a Local Area Network (LAN) system, an ethernet adapter exchanges data with a host through programmed I/O (PIO) and FIFO buffers. The receive PIO employs a DMA ring buffer backup so incoming packets can be copied directly into host memory when the PIO FIFO buffer is full. The adapter may be programmed to generate early receive interrupts when only a portion of a packet has been received from the network, so as to decrease latency. The adapter may also be programmed to generate a second early interrupt so that the copying of a large packet to the host may overlap reception of the packet end. The adapter to begin packet transmission before the packet is completely transferred from the host to the adapter, which further reduces latency.

Abstract: In a computer system having a central processing unit which employs software drivers as part of a host for controlling peripheral units and including a bus for connecting with adapters for the peripheral units, wherein each adapter has distributed intelligence means for interpreting simple command information and a nonvolatile storage element for storing default configuration information, including a default port address for communication, a method is provided for configuring such intelligent adapters connected to the bus.

Abstract: In a Local Area Network (LAN) system, an ethernet adapter exchanges data with a host through programmed I/O (PIO) and FIFO buffers. The receive PIO employs a DMA ring buffer backup so incoming packets can be copied directly into host memory when the PIO FIFO buffer is full. The adapter may be programmed to generate early receive interrupts when only a portion of a packet has been received from the network, so as to decrease latency. The adapter may also be programmed to generate a second early interrupt so that the copying of a large packet to the host may overlap reception of the packet end. The adapter may also be programmed to begin packet transmission before the packet is completely transferred from the host to the adapter, which further reduces latency.