Multi-output packet server with independent streams

Abstract

A method of serving content to multiple clients via a network is provided. Independent sessions with each of a plurality of clients are maintained, wherein the number of clients in the plurality of clients can vary over time, and wherein the start of each session and the end of each session can be independent of the start and end of other sessions. A stream of packet payloads is received, each packet payload of the stream of packet payloads including data generated from the content, wherein each packet payload in at least a subset of the stream of packet payloads includes a different set of data. Each packet payload in the stream of packet payloads is transmitted to each client of the plurality of clients in corresponding packets, wherein the packet payload transmitted to a client at any particular time is independent of the state of the corresponding session.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001] This application claims priority to U.S. Provisional Application No. 60 / 274,445, filed Mar. 9, 2001, and entitled "MULTI-OUTPUT PACKET SERVER WITH INDEPENDENT STREAMS", which is herein incorporated by reference in its entirety for all purposes.FIELD OF THE INVENTION[0002] The present invention generally relates to communications systems. In particular, the present invention relates to methods and apparatus for delivering content in communications systems to multiple locations.BACKGROUND OF THE INVENTION[0003] Digital content transmission between a server and multiple receivers over a communications channel has been the subject of much literature. In general, a design goal of a content delivery system is to allow each recipient to receive an exact copy of content transmitted over a channel by a server with some level of certainty. Hereafter, content may be a file, a stream of data or some other form of data. A content delivery system may...

AI Technical Summary

Benefits of technology

[0018] In yet another embodiment, a method of serving content to multiple clients via a network, the content represented by a plurality of input symbols, wherein the network includes a multicast network, is provided. The method comprises generating output symbols from the input symbols, and assembling output symbols into a stream of packets, wherein each packet in the stream of packets includes a set of at least one output symbol, wherein each packet includes a different set of the output symbols. The method also comprises transmitting, using multicasting, the stream of packets to a plurality of multicast clients via the multicast network, wherein the number of multicast clients in the plurality of multicast clients can vary over time, and wherein a multicast client can regenerate the ordered set of input symbols to a desired accuracy from any N output symbols included in a set of packets received by the multicast client, wherein N is an integer greater than 1 and less than the number of possible output symbols.

[0022] In still another embodiment, a server system for serving content to multiple clients via a network including a multicast network is provided. The server system comprises a plurality of servers. Each of the plurality of servers includes a respective storage device that stores the content to be served, the content including input symbols, and a respective encoding generator coupled with the respective storage device that generates output symbols from the input symbols. Each of the plurality of servers also includes a respective transmitter coupled with the respective encoding generator and with the network that assembles the output symbols into multicast packets, wherein each multicast packet includes a different set of output symbols and transmits, using multicast, the multicast packets to a respective plurality of multicast clients via the network, wherein the number of multicast clients in the respective plurality of multicast clients can vary over time, and wherein a multicast client can regenerate the input symbols to a desired accuracy from any N output symbols included in a set of multicast packets received by the multicast client, wherein N is an integer greater than 1 and less than the number of possible output symbols.

Problems solved by technology

If the number of clients is instead 1,000 then the disk contention problem is ten times worse.

Furthermore, if any of these resources is a bottleneck, then this resource will dictate the capacity of the server in terms of concurrent client downloads or streams.

One issue with this approach is that such a transmission is not reactive to congestion in the network, and may cause the intervening networking infrastructure to overload.

Such an overload may cause massive packet loss and may negatively impact other connections sharing the same network infrastructure.

Another concern is that such a transmission is not protected against losses, and thus even when a substantial fraction of packets do arrive at clients, the play out quality may be quite poor when there are packet losses containing important piece of the original stream.

For example, with Moving Picture Experts Group (MPEG) streams, the loss of packets containing I-frames may cause many frames of the play out to display incorrectly.

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