Whatever the system, no device in it should be allowed to transmit until that device has evidence that the intended receiver is able to receive and is prepared to accept the transmission. What if the receiver does not expect a transmission, is busy, or is out of commission? With no way to determine the status of intended receiver, the transmitting device may waste its time sending data to a nonfunctioning receiver or may interfere with signals already on the link. The line discipline function of the data link layer oversees the establishment of links and the right of a particular device to transmit at a given time. Line discipline answers the question. Who should send now?
No comments:
Post a Comment