DYNAMIC OPTIMIZATION FOR RECEIVERS USING DISTANCE BETWEEN A REPAIR HEAD AND A MEMBER STATION IN A REPAIR GROUP FOR RECEIVERS HAVING A CLOSELY KNIT TOPOLOGICAL ARRANGEMENT TO LOCATE REPAIR HEADS NEAR THE MEMBER STATIONS WHICH THEY SERVE IN TREE BASED REPAIR IN RELIABLE MULTICAST PROTOCOL

• US 6,507,562 B1
• Filed: 06/18/1999
• Issued: 01/14/2003
• Est. Priority Date: 06/30/1998
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Perlman, Radia J., Chiu, Dah Ming, Hanna, Stephen R., Kadansky, Miriam C., Wesley, Joseph S., Hurst, Stephen A., Rosenzweig, Philip M.
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Qureshi, Afsar M.
• Application Number:
  US09/336,660
• Time in Patent Office: 1,306 Days
• Field of Search: 370/216, 370/242, 370/254, 370/226, 370/227, 370/312, 370/356, 370/389, 370/390, 370/392, 370/408, 370/432, 714/18, 714/748, 714/798, 340/825.2, 340/3.51, 340/825.08, 340/825.07, 725/34, 709/230, 709/238, 709/227, 709/239
• US Class Current: 370/216
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1868 Measures taken after transmission, e.g. acknowledgments
• CPC Class Codes: H04L 12/1877 Measures taken prior to transmission

Abstract

Receiver stations located close together in a computer network dynamically form a multicast repair tree by a plurality of receiver stations choosing a repair head station from among the closely located receiver stations. A receiver station calculates its distance from a repair head station by subtracting the decremented TTL value read from the IP header from the initial value of the TTL parameter carried in field TTL SCOPE of HELLO messages, transmitted by repair head stations. Using a criteria that a closer repair head station is a more optimum repair head station, receiver stations listen to each received HELLO message, calculate the distance to the repair head station, and reaffiliate with the closest repair head station.

Claims

1. A method of optimizing a repair tree in multicast communications, comprising:

detecting a first distance to a first repair head station;

detecting a second distance to a second repair head station;

reaffiliating by receiver stations to said first repair head station in response to a comparison between said first distance and said second distance.

2. The method as in claim 1 wherein said reaffiliating step further comprises:

selecting a closer repair head station for a receiver station to reaffiliate to.

3. The method as in claim 1 further comprising:

initiating said reaffiliation by a receiver head station.

4. The method as in claim 1 further comprising:

initiating said reaffiliation by a repair head station.

5. The method as in claim 1 further comprising:

receiving a message from a repair head station;

reading a value of a first TTL parameter from said message;

reading a value of a second TTL parameter decremented by each router through which said message was routed, said second TTL parameter having had said first TTL parameter as an initial value;

detecting a distance to said repair head station in response to said first TTL parameter and said second TTL parameter.

6. The method as in claim 5 further comprising;

determining said distance to said repair head station by subtracting said second TTL parameter from said first TTL parameter.

7. The method as in claim 5 further comprising;

writing by said repair head station said first TTL parameter into a first field of said message, said first field not changed by a router as said message is routed by a router;

writing by said repair head station a value of said first TTL parameter into a second field of a message, said second field being in a header of said message said second field being changed by each router which routes said message so that upon receipt of said message by said receiver station said second field contains said second TTL parameter.

8. The method of claim 7 further comprising;

selecting as said second field a TTL field of an IP protocol header so that a router following IP protocol decrements a value found in second field before routing said message.

9. The method of claim 1 further comprising:

making a distance comparison by a receiver station between a current repair head station and another repair head station upon receipt by said receiver station of a message from said another repair head station, said message containing sufficient information to make said comparison.