Network-Based Service for the Repair of IP Multicast Sessions

Abstract

A system and method are disclosed for the repair of IP multicast sessions. A repair server polls multiple transmit servers to accumulate as many of the packets missing from the multicast session as possible. A network includes a source of multicast packets in a multicast session and a plurality of multicast recipients in that session. A repair server in the network provides the packets it receives to the recipients. The repair server includes a missing packet detector. There is a plurality of retransmit servers in the network buffering portions of the packets they respectively receive during the session. The repair server maintains an ordered list of the retransmit servers that are most likely to have buffered copies of packets missing from the session. When the repair server detects that there are packets missing from the session it has received, it uses the ordered list to sequentially request the missing packets from respective ones of the plurality of retransmit servers.

What is claimed is: 
     
         1 . A system, comprising:
 a memory that stores instructions;   a processor that executes the instructions to perform operations, the operations comprising:
 accumulating a count of successful responses from each retransmit server in an ordered list of retransmit servers, wherein the retransmit servers in the ordered list of retransmit servers are ordered based on a likelihood of each retransmit server having buffered copies of packets missing from a multicast session; 
 determining a ranking for each of the retransmit servers based on the count of successful responses accumulated from each of the retransmit servers in the ordered list; and 
 reordering the ordered list into a reordered list based on the ranking determined for each of the retransmit servers. 
   
     
     
         2 . The system of  claim 1 , wherein the operations further comprise generating the ordered list of retransmit servers based on the likelihood of each retransmit server having the buffered copies of packets missing from the multicast session. 
     
     
         3 . The system of  claim 1 , wherein the operations further comprise sequentially requesting the buffered copies of the packets missing from the multicast session based on the reordered list. 
     
     
         4 . The system of  claim 1 , wherein the operations further comprise receiving a receiver report from each retransmit server during the multicast session. 
     
     
         5 . The system of  claim 1 , wherein the operations further comprise receiving a definition of the multicast group session. 
     
     
         6 . The system of  claim 1 , wherein the operations further comprise receiving, from a repair server, a request for the buffered copies of the packets missing from the multicast session. 
     
     
         7 . The system of  claim 6 , wherein the operations further comprise transmitting, to the repair server and in a unicast response, the buffered copies of the packets missing from the multicast session. 
     
     
         8 . The system of  claim 1 , wherein the operations further comprise utilizing an interarrival jitter field as a ranking criterion for adjusting the ordered list. 
     
     
         9 . The system of  claim 1 , wherein the operations further comprise utilizing a cumulative number of packets lost field as a ranking criterion for adjusting the ordered list. 
     
     
         10 . The system of  claim 1 , wherein the operations further comprise utilizing round trip delay information as a ranking criterion for adjusting the ordered list. 
     
     
         11 . The system of  claim 1 , wherein the operations further comprise utilizing a fraction lost field as a ranking criterion for adjusting the ordered list. 
     
     
         12 . The system of  claim 1 , wherein the operations further comprise transmitting an adaptive enhanced reliability stream of packets in the multicast session. 
     
     
         13 . The system of  claim 1 , wherein the operations further comprise selecting a retransmit server from the reordered list based on the ranking. 
     
     
         14 . A method, comprising:
 accumulating a count of successful responses from each retransmit server in an ordered list of retransmit servers, wherein the retransmit servers in the ordered list of retransmit servers are ordered based on a likelihood of each retransmit server having buffered copies of packets missing from a multicast session;   determining, by utilizing instructions from a memory that are executed by a processor, a ranking for each of the retransmit servers based on the count of successful responses accumulated from each of the retransmit servers in the ordered list; and   reordering the ordered list into a reordered list based on the ranking determined for each of the retransmit servers.   
     
     
         15 . The method of  claim 14 , further comprising generating the ordered list of retransmit servers based on the likelihood of each retransmit server having the buffered copies of packets missing from the multicast session. 
     
     
         16 . The method of  claim 14 , further comprising sequentially requesting the buffered copies of the packets missing from the multicast session based on the reordered list. 
     
     
         17 . The method of  claim 14 , further comprising selecting a retransmit server from the reordered list based on the ranking. 
     
     
         18 . The method of  claim 14 , further comprising receiving a receiver report from each retransmit server during the multicast session. 
     
     
         19 . The method of  claim 14 , further comprising transmitting an adaptive enhanced reliability stream of packets in the multicast session. 
     
     
         20 . A non-transitory computer-readable device comprising instructions, which, when loaded and executed by a processor, cause the processor to perform operations, the operations comprising:
 accumulating a count of successful responses from each retransmit server in an ordered list of retransmit servers, wherein the retransmit servers in the ordered list of retransmit servers are ordered based on a likelihood of each retransmit server having buffered copies of packets missing from a multicast session;   determining a ranking for each of the retransmit servers based on the count of successful responses accumulated from each of the retransmit servers in the ordered list; and   reordering the ordered list into a reordered list based on the ranking determined for each of the retransmit servers.