Hello Friends, In this blog post(Error Control Using Data Link Layer In Computer Network) I am going to explain one important factor ‘Error Control’ mechanism which is used at the data link layer while making the data transmission in or out.
Inside this blog post(Error Control Using Data Link Layer In Computer Network), we are going to discuss What is error control in the data link layer? How will you achieve flow control and error control in the data link layer?….
…. Why flow control and error control mechanism are implemented in the data link layer as well as in the transport layer? What are the two data link control?|Error Control Using Data Link Layer In Computer Network|
The data link layer gives a surety of error control that all frames are eventually delivered to the network layer at the destination and in the proper order. Suppose that the sender just kept outputting frames without regard to whether they were arriving properly. |Error Control Using Data Link Layer In Computer Network|
This might be fine for unacknowledged connectionless service but would most certainly not be fine for reliable, connection-oriented service.
The usual way to ensure reliable delivery is to provide the sender with some feedback about what is happening at the other end of the line.
Typically the protocol calls for the receiver to send back special control frames bearing positive or negative acknowledgements about the incoming frames.
If the sender receives a positive acknowledgement about a frame, it knows the frame has arrived safely.
On the other hand, a negative acknowledgement means that something has gone wrong and frame must be transmitted again.
An additional complication comes from the possibility that the hardware troubles may cause a frame to vanish completely(eg. in a noise burst).
In this case, the receiver will not react at all, since it has no reason to react. It should be clear that a protocol in which the sender transmitted a frame and then waited for an acknowledgement, positive or negative, would hang forever if a frame were ever completely lost due to malfunction hardware.
This possibility is dealt with by introducing timers into the data link layer.
When the transmits a frame, it generally also starts a timer.
The timer is set to go off after an interval long enough for the frame to reach the destination, be processed there, and have the acknowledgement propagate back to the sender.
Normally the frame will be correctly received and the acknowledgement will get back before the timer runs out, In which case it will be cancelled.
However, if either the frame or the acknowledgement is lost, the timer will go off, altering the sender to a potential problem. The obvious solution for error control is to just transmit the frame again.
However, When frames may be transmitted multiple times there is a danger that the receiver will accept the same frame two or more times and pass it to the network layer more than once.
To prevent this from happening, the error control is generally necessary to assign a sequence number to outgoing frames, So that the receiver can distinguish a retransmission from originals.|Error Control Using Data Link Layer In Computer Network|
Within this blog post(Error Control Using Data Link Layer In Computer Network), we have gone through What is error control in the data link layer? How will you achieve flow control and error control in the data link layer? Why flow control and error control mechanism are implemented in the data link layer as well as in the transport layer? What are the two data link control?. Datalink and its protocols play an important role in data communication and ensure the reliable delivery of data between the devices.
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