REPAIR TIME-TO-LIVE (TTL) COMPUTATION AND CORRECTION METHOD AND APPARATUS TO PERFORM LOCALIZED RETRANSMISSION OF DATA IN A MULTICAST DATA DISTRIBUTION SETUP/FRAMEWORK

摘要

Time To Live ("TTL") value for repair data units (34) transmitted from a repair head (12) to a standard destination device (14) in a communications network is determined for multicast transmission. The repair head (12) monitors the path between the repair head and the standard destination devices by exchanging messages (36, 38, 39) with the standard destination devices. The repair head transmits control messages (36) to each destination device including a dispatched TTL value and an Internet Protocol ("IP") TTL value. If the control message fails to reach one of the standard destination devices, that standard destination device transmits a transmission failure indication (38) to the repair head subsequently the TTL value employed for the control message is increased. Following receipt of the control message, the standard destination device calculates the TTL value required to transmit a data unit from the repair head to the standard destination device by substracting the IP TTL value from the dispatch TTL value.