When the network needs to control the congestion, the signal will be delivered to the receiver at the fast speed, and was brought to the initiator by the acknowledgement frame.
当网络需要预防拥塞发生时，标记将以最快的速度到达接收端，并且被确认帧带回到发送端。
If the sender receives a positive acknowledgement about a frame, it knows the frame has arrived safely.
如果发送端收到了有关帧的肯定应答，它就知道发送的帧已经安全到达。
On the other hand, a negative acknowledgement means that something has gone wrong, and the frame must be transmitted again.
另一方面，否定应答则意味着出现了某种错误，应该重新发送出错的帧。
On the other hand, a negative acknowledgement means that something has gone wrong, and the frame must be transmitted again.
另一方面，否定应答则意味着出现了某种错误，应该重新发送出错的帧。
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