Repair TTL computation and correction mechanism to perform localized repairs in a multicast data distribution setup/framework

摘要

Determination of a Time To Live ("TTL") hop count for repair data units transmitted from a repair head to a standard destination device in a communications network is facilitated for multicast transmission. The repair head destination device monitors the path between the repair head destination device and the standard destination devices by exchanging messages with the respective standard destination devices. The repair head transmits control messages 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 to the repair head destination device. In response to the transmission failure indication 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 subtracting the IP TTL value from the dispatched TTL value. If the calculated TTL difference value is non-zero then an excess-TTL indication is transmitted from the standard destination device to the repair head destination device.