Introduction to Data Link Layer || Lesson 7 || Computer Networks || Learning Monkey ||

Here we will have Introduction to Data Link Layer

The Data Link Layer transforms the physical layer, a raw transmission facility, into a reliable link. It makes the physical layer appear error-free to the upper layer (network
layer).
Framing: The data link layer divides the stream of bits received from the network
layer into manageable data units called frames.

Physical addressing: If frames are to be distributed to different systems on the
network, the data link layer adds a header to the frame to define the sender and/or
the receiver of the frame. If the frame is intended for a system outside the sender's
network, the receiver address is the address of the device that connects the network
to the next one.

Flow control: If the rate at which the data are absorbed by the receiver is less than
the rate at which data are produced in the sender, the data link layer imposes a flow
control mechanism to avoid overwhelming the receiver.

Error control: The data link layer adds reliability to the physical layer by adding
mechanisms to detect and retransmit damaged or lost frames. It also uses a mechanism to recognize duplicate frames. Error control is normally achieved through a
trailer added to the end of the frame.

Access control: When two or more devices are connected to the same link, data
link-layer protocols are necessary to determine which device has control over
the link at any given time.

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[sakivelaanusha]

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[iamgroot]

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