The file transfer control implements a Fully Reliable service for multicasting, ensuring that each packet sent is received correctly. If the receiver determines that packets are missing or damaged, it can send a negative acknowledgment (NAK) to the sender requesting that the packets be resent.
In the Fully Reliable mode, the file transfer service performs flow control in addition to the rate control done by the sender. If the sender is transmitting packets too fast, the receiver sends a Throttle NAK indicating that the transfer should slow down. The receiver also sends an Idle NAK when it is busy or has not heard from the sender for awhile.
The NetShow file transfer control uses the Fully Reliable service as the default. If the sender does not use the Fully Reliable service, however, the control will still receive transfers, but will not be able to request the retransmission of any missing packets. The Fully Reliable service can be turned off with the FullyReliableService property.
A two-way (bidirectional) network is required for the Fully Reliable service.
The Fully Reliable service requires that forward error-correction (FEC) be used.
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