Method and apparatus for multicast delivery of information
First Claim
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1. A method, comprising:
- transmitting a data stream to each of a plurality of clients via a multicast communication session, said data stream comprising a plurality of data packets arranged in a predefined sequence, each of said plurality of data packets having associated with it a sequence identifier for identifying a respective sequence position;
receiving a client request for retransmission of a previously transmitted data packet; and
retransmitting said requested data packet to said requesting client via at least one of a unicast communications channel and said multicast communication session.
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Abstract
A method, apparatus and data structure are described which enables complete datagram reception by a plurality of clients using a UDP multicast transport mechanism, wherein missing packets are retransmitted from a server using either a multicast transport mechanism or a unicast connection, in response to receipt by the server of client request to retransmit. Data structure of packets includes a new sequence identifier field in the header for identification of proper packet position within a data stream.
113 Citations
18 Claims
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1. A method, comprising:
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transmitting a data stream to each of a plurality of clients via a multicast communication session, said data stream comprising a plurality of data packets arranged in a predefined sequence, each of said plurality of data packets having associated with it a sequence identifier for identifying a respective sequence position;
receiving a client request for retransmission of a previously transmitted data packet; and
retransmitting said requested data packet to said requesting client via at least one of a unicast communications channel and said multicast communication session. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method, comprising:
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receiving a data stream via a multicast communications session, said data stream comprising a plurality of data packets ordered in a predefined sequence, each of said plurality of data packets including a sequence identifier for identifying a corresponding respective sequence position;
determining, using said sequence identifiers, whether ones of said plurality of data packets are missing from said data stream; and
receiving missing ones of said plurality of data packets via a unicast communications channel. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A data structure, comprising:
a plurality of Real-Time Transport Protocol (RTP) packets having respective header (H) and payload (P) portions, each of said RTP packets including a sequence identifier (RTPHSI) within a respective header portion for identifying a respective location within an information stream. - View Dependent Claims (17)
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18. A apparatus comprising:
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means for transmitting a data stream to each of a plurality of clients via a multicast communication session, said data stream comprising a plurality of data packets arranged in a predefined sequence, each of said plurality of data packets having associated with it a sequence identifier for identifying a respective sequence position;
means for receiving a client request for retransmission of a previously transmitted data packet; and
means for retransmitting said requested data packet to said requesting client via at least one of a unicast communications channel and said multicast communication session.
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Specification