Distribution of data flows to local loop subscribers by an access multiplexer
First Claim
1. A method of distributing a flow of data embedded in a plurality of cells to zero or more subscribers, the method comprising:
- receiving a cell in conformance with the asynchronous transfer mode (ATM) protocol;
identifying zero or more virtual circuits of subscribers that are to receive the cell, using a VPIVCI number in the cell and a mapping between cell VPI/VCI numbers and the subscriber virtual circuits;
transmitting a copy of the cell on each subscriber virtual circuit that is identified, wherein identification of each subscriber virtual circuit provides at least an output VPI/VCI number and an output port;
repeating the acts of receiving, identifying and transmitting until a message is received from a subscriber requesting a new flow to be supplied thereto;
changing the mapping, to map a new VPI/VCI number of a cell of the new flow to the virtual circuit of the subscriber, without regard to an input VPI/VCI number of the subscriber'"'"'s virtual circuit; and
returning to the act of repeating;
wherein the virtual circuit to each subscriber is kept intact during the method.
2 Assignments
0 Petitions
Accused Products
Abstract
An apparatus that supports a communication link (such as DSL) in the local loop has hardware to distribute a copy of one or more data flows to any of a number of devices (e.g. “set-top boxes”) that are each connected to the apparatus by the link. In some embodiments, the apparatus receives only one copy of a number of video feeds for distribution from a video head end that is coupled thereto e.g. via an ATM network. In such embodiments, the apparatus selectively transfers a copy of one of the video feeds being received, to each set-top box. Distribution of data flows in the apparatus can be implemented by a point to multipoint virtual circuit, although a change in a video feed being supplied to a subscriber requires tearing down the subscriber'"'"'s old virtual circuit leaf and setting up a new virtual circuit leaf to the subscriber. The time delay and overhead associated with such virtual circuit changes are eliminated in certain embodiments by changing only an internal mapping. Specifically an association between a subscriber'"'"'s virtual circuit and a first virtual circuit carrying the currently-supplied video feed is erased, and a new association is formed between the subscriber'"'"'s virtual circuit and a second virtual circuit that is carrying the video feed to be supplied. During such a change, the subscriber'"'"'s virtual circuit is kept intact (and in addition, the first and second virtual circuits are kept intact as well), because a simple change in VC-VC associations implements channel change.
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Citations
27 Claims
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1. A method of distributing a flow of data embedded in a plurality of cells to zero or more subscribers, the method comprising:
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receiving a cell in conformance with the asynchronous transfer mode (ATM) protocol;
identifying zero or more virtual circuits of subscribers that are to receive the cell, using a VPIVCI number in the cell and a mapping between cell VPI/VCI numbers and the subscriber virtual circuits;
transmitting a copy of the cell on each subscriber virtual circuit that is identified, wherein identification of each subscriber virtual circuit provides at least an output VPI/VCI number and an output port;
repeating the acts of receiving, identifying and transmitting until a message is received from a subscriber requesting a new flow to be supplied thereto;
changing the mapping, to map a new VPI/VCI number of a cell of the new flow to the virtual circuit of the subscriber, without regard to an input VPI/VCI number of the subscriber'"'"'s virtual circuit; and
returning to the act of repeating;
wherein the virtual circuit to each subscriber is kept intact during the method. - View Dependent Claims (2, 3, 4, 5)
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6. A method of operating a device (hereinafter “
- access multiplexer”
) that is connected directly to customer premises equipment (hereinafter “
CPE”
) of a number of subscribers, the method comprising;
the access multiplexer receiving only one copy of each of a number of video channels available for distribution to the subscribers, each video channel being received as a flow of units of data;
the access multiplexer using an identifier (hereinafter “
flow identifier”
) in a header of each unit of data that is received, to find zero or more identifiers of virtual circuits (hereinafter “
subscriber VCs”
) to CPE of the subscribers, based on a mapping between flow identifiers and identifiers of subscriber VCs;
the access multiplexer transmitting a copy of the unit of data to each subscriber VC identified by the act of using the flow identifier with the mapping; and
the access multiplexer changing the mapping while maintaining each subscriber VC intact, by removing in the mapping an association of the flow identifier with the subscriber VC and adding in the mapping another association of a new flow identifier with the subscriber VC, after the access multiplexer receives a request (hereinafter “
channel change request”
) from the subscriber indicating a new video channel. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
- access multiplexer”
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14. A method of supplying video, the method comprising:
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setting up a virtual circuit (hereinafter “
subscriber VC”
) having one end (hereinafter “
ingress end”
) in equipment (hereinafter “
access multiplexer”
) of a service provider, and another end (hereinafter “
egress end”
) in equipment (hereinafter “
CPE”
) of a subscriber, wherein the subscriber VC is carried only by a local loop between the access multiplexer and the CPE;
setting up another virtual circuit (hereinafter “
trunk VC”
) having one end (hereinafter “
egress end”
) in the access multiplexer and another end (hereinafter “
ingress end”
) in a device (hereinafter “
upstream node”
);
wherein the upstream node and the access multiplexer communicate with one another via a physical layer protocol that conforms to a plesiochronous digital hierarchy;
the access multiplexer forming a mapping between the trunk VC and the subscriber VC, after the CPE transmits to the access multiplexer a request to receive a flow of data in the trunk VC;
the access multiplexer receiving only one copy of the flow of data via a trunk VC from the upstream node; and
the access multiplexer transmitting a copy of the flow of data to the subscriber VC based on the mapping and regardless of any identifier of the ingress end of the subscriber VC. - View Dependent Claims (15, 16, 17)
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18. An apparatus comprising:
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a first line unit (hereinafter “
optical line unit”
) that receives a single copy of number of flows of data for distribution to subscribers;
a number of second line units (hereinafter “
subscriber line units”
) that are directly coupled to local loops of subscribers, each subscriber line unit being coupled to the optical line unit by a bus;
a network processor that transfers zero or more flows of data from the optical line unit into each subscriber line unit based on a mapping contained therein, between identifiers of flows and identifiers of subscribers; and
a control unit coupled to the network processor to update the mapping, in response to a message from a subscriber. - View Dependent Claims (19, 20)
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21. A method of distributing to each of a number of subscribers one of a number of flows of data, the method comprising:
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using an access multiplexer that is coupled to each subscriber by a local loop to end each virtual circuit (hereinafter “
trunk VC”
) carrying a flow of data from an upstream device before the flow of data reaches a subscriber;
using the access multiplexer to originate a virtual circuit (hereinafter “
subscriber VC”
) to each subscriber, to supply one of the flows of data being received in the trunk VCs;
forming a mapping in the access multiplexer, between each subscriber VC and a trunk VC that carries a data flow requested by the subscriber, regardless of any identifier of the ingress end of the subscriber VC; and
for each data flow received from a trunk VC, the access multiplexer transferring a copy of the data flow to zero or more subscriber VCs identified by the mapping. - View Dependent Claims (22)
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23. A method of distributing to each of a number of subscribers one of a numbers of flows of data, the method comprising:
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using an access multiplexer that is coupled to each subscriber by a local loop, to transfer a copy of a data flow to zero or more subscriber VCs identified by an internal mapping; and
in response to a request, erasing in the mapping, an identifier of the subscriber VC associated with a first trunk VC carrying the data flow being currently received and adding to the mapping the identifier of the subscriber VC in association with a second identifier of a second trunk VC carrying another data flow that has been identified in the request, without tearing down or setting up the subscriber VC. - View Dependent Claims (24, 25, 26, 27)
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Specification