Distributed Coordination of Network Elements for Packet Encapsulation

Abstract

In one embodiment, each of a plurality of encapsulator devices receives a source stream of encoded packets in a first transport format to be converted to packets of an output stream in a second transport format for communication over a data network. Each encapsulator device generates a one or more fundamental identifying characteristics for the output stream based on information contained in one or more fields of a packet in the source stream so that the packets in the output stream generated by each of the encapsulator devices from the source stream are coordinated with respect to each other.

1 . A method comprising:
 at each of a plurality of encapsulator devices:
 receiving a source stream of encoded packets in a first transport format to be converted to packets of an output stream in a second transport format for communication over a data network; and 
 generating one or more fundamental identifying characteristics for the output stream based on information contained in one or more fields of a packet in the source stream so that the packets in the output stream generated by each of the encapsulator devices from the source stream are coordinated with respect to each other. 
   
     
     
         2 . The method of  claim 1 , wherein generating comprises applying a first one-to-one mapping function at each of the plurality of encapsulator devices to information contained in one or more fields of a packet in the source stream to produce a packet sequence number. 
     
     
         3 . The method of  claim 2 , and further comprising applying a second one-to-one mapping function to information contained in one or more fields of a packet in the source stream to generate a timing reference for a packet in the output stream in the second transport format. 
     
     
         4 . The method of  claim 3 , wherein applying comprise a second one-to-one mapping function to information contained in one or more fields of a packet in the source stream to generate an initial timing reference, and further comprising generating timing references for subsequent packets in the output stream based on the initial timing reference and a clock rate of content of the packets in the source stream. 
     
     
         5 . The method of  claim 1 , wherein generating comprises generating an initial packet sequence number for a packet in the output stream in the second transport format, and generating subsequent packet sequence numbers for subsequent packets in the output stream from the initial packet sequence number. 
     
     
         6 . The method of  claim 1 , wherein generating comprises generating, at the plurality of encapsulator devices, the same packet sequence numbers for packets in their output streams which carry the same data even if the respective encapsulator devices start generating packet sequence numbers based on different packets in the source stream. 
     
     
         7 . The method of  claim 1 , and further comprising generating a source stream identifier for the output stream at each of the plurality of encapsulator devices from information contained in packets of the source stream such that the output stream from each encapsulator devices has the same source stream identifier for the same source stream. 
     
     
         8 . The method of  claim 7 , wherein generating the source stream identifier for the output stream comprises applying a one-to-one mapping function to information contained in one or more fields of the source packets of the source stream. 
     
     
         9 . The method of  claim 7 , wherein receiving the source stream comprises receiving a multicast session for a channel of video programming, wherein each channel of video programming of a plurality of channels is identified by a source address and a destination multicast address such that the source address may be common across multiple channels and in some circumstances the destination address is unique for each channel, and wherein generating the source identifier is based on a combination of the destination multicast address and the source address. 
     
     
         10 . The method of  claim 9 , wherein generating the source identifier comprises applying a one-to-one mapping function to a combination of the destination multicast address and the source address. 
     
     
         11 . The method of  claim 1 , wherein the source stream comprises an MPEG2 transport stream and the output stream comprises a real-time transport protocol (RTP) stream. 
     
     
         12 . A method comprising:
 at a plurality of encapsulator devices:
 receiving a source stream of encoded packets in a first transport format to be converted to an output stream of packets in a second transport format for communication over a data network; 
   at a first encapsulator device:
 generating preliminary encapsulation and packetization of the packets of the source stream into packets for the output stream of packets in the second transport format; 
 transmitting information describing the preliminary encapsulation and packetization to at least one other encapsulator device in the plurality of encapsulator devices; and 
   at the at least one other encapsulator device:
 receiving the information describing the preliminary encapsulation and packetization from the first encapsulator device; and 
 generating an output stream of packets in the second transport format based on packets of the source stream and the information describing the preliminary encapsulation and packetization received from the first encapsulator device. 
   
     
     
         13 . The method of  claim 12 , wherein at the at least one other encapsulator device, transmitting to the first encapsulator device a request for data in the source stream that is determined to be missing at the at least one other encapsulator device. 
     
     
         14 . The method of  claim 12 , wherein at the first encapsulator device, generating final encapsulation and packetization based on feedback received from the at least one other encapsulator device, transmitting the final encapsulation and packetization to the at least one other encapsulator device, and wherein generating the output stream at the at least one other encapsulator device is based on the final encapsulation and packetization. 
     
     
         15 . The method of  claim 12 , wherein the source stream comprises an MPEG2 transport stream and the output stream comprises a real-time transport protocol (RTP) stream. 
     
     
         16 . A device comprising:
 a network interface unit configured to receive a source stream of encoded video packets in a first transport format; and   a processor configured to be coupled to the first network interface unit, wherein the processor is configured to convert packets in the source stream into packets for an output stream in a second transport format, and to generate one or more fundamental identifying characteristics for the output stream based on information contained in one or more fields of a packet in the source stream.   
     
     
         17 . The device of  claim 16 , wherein the processor is configured to generate a packet sequence number for each packet in the output stream by applying a first one-to-one mapping function to information contained in one or more fields of a packet in the source stream. 
     
     
         18 . The device of  claim 17 , wherein the processor is further configured to apply a second one-to-one mapping function to information contained in one or more fields of a packet in the source stream to generate a timing reference for a packet in the output stream in the second transport format. 
     
     
         19 . The device of  claim 16 , wherein the processor is further configured to generate a source stream identifier for the output stream from information contained in packets of the source stream. 
     
     
         20 . The device of  claim 19 , wherein the processor is configured to generate the source stream identifier for the output stream by applying a one-to-one mapping function to a combination of a source address and a destination multicast address contained in a packet of the source stream. 
     
     
         21 . A system comprising a plurality of devices as recited in  claim 16 , wherein each of the plurality of devices is configured to receive the same source stream and to generate the same one or more fundamental identifying characteristics from the source stream. 
     
     
         22 . A processor readable memory medium encoded with instructions that, when executed by a processor, cause the processor to:
 receive a source stream of encoded packets in a first transport format to be converted to packets of an output stream in a second transport format for communication over a data network; and   generate one or more fundamental identifying characteristics for the output stream based on information contained in one or more fields of a packet in the source stream.   
     
     
         23 . The processor readable medium of  claim 22 , wherein the instructions that generate comprise instructions configured to generate a packet sequence number for a packet in the output stream by applying a first one-to-one mapping function to information contained in one or more fields of a packet in the source stream. 
     
     
         24 . The processor readable medium of  claim 23 , and further comprising instructions that, when executed by the processor, cause the processor to apply a second one-to-one mapping function to information contained in one or more fields of a packet in the source stream to generate a timing reference for a packet in the output stream. 
     
     
         25 . The processor readable medium of  claim 22 , and further comprising instructions, that when executed by the processor, cause the processor to generate a source stream identifier for the output stream from information contained in a packet of the source stream.