Data Link Layer is the second layer in the OSI reference model. It represents creating a shared transmission medium and frequent transmission of the data frame in a computer transmission setting.
It obtains a natural flow of items for the physical layer at the sender device. The primary stream of data is generated using different technologies like cable, DSL, wireless, optical fibre, etc.
Services Provided By Data Link Layer
Data Link Layer is a protocol layer that is typically used in programmes to manage and control the data transmission between the source and destination machines. It is simply responsible for the exchange of frames among nodes or machines over physical network media. This layer is closest to the physical layer (Hardware).
The second of the seven layers in the Open System Interconnection (OSI) reference model for computer networking, the Data Link Layer, is essentially located above Physical Layer.
This layer typically offers data reliability, as well as a number of tools for creating, maintaining and releasing connections between network nodes for data links. Its duties include obtaining data bits, typically from the physical layer and grouping, those bits into units known as data link frames so they can be transmitted further. It must also deal with any errors that may occur during bit transmission.
Services Provided To Data Link Layer
Supporting error-free transmission is the data link layer’s main function. Raw bits of data are sent from the hub of the sender to the hub of the receiver by the physical layer. Some errors in the transmitted data should be recognised and fixed by the data link layer.
A distinct connection to the network layer is offered by the data link layer. By keeping up with multiple services, it is used to manage sender and receiver inconsistency, control the data stream and handle communication bugs. It can carry out these operations using the next technique
Actual Communication
Data Link Layer in this communication merely transmits data frames over a physical medium. The real order of events is Network Layer -> Data Link Layer -> Physical Layer on the sending machine, followed by physical media and Physical Layer -> Data Link Layer -> Network Layer on the receiving machine.
Virtual Communication
There is no physical medium available in this communication for the Data Link Layer to transmit data over. Two Data Link Layers communicating with each other using data link protocol is only conceivable and can only be visualised.
Types Of Services Provided By Data Link Layer
Unacknowledged connectionless service
This consists of separate frames without any sort of acknowledgement structure going from the source host to the destination host. It lacks any launched or established links. Due to channel noise, frame recovery is not possible.
Acknowledged connectionless service
More errors can occur due to the transmission medium. To ensure that the frame has been correctly transmitted, an acceptance service must be provided for each frame shared between two hosts.
Acknowledged connection-oriented service
By establishing a link between the source and destination hosts before any information removal takes place, this layer assists the network layer in providing this service.
Framing
It receives an unclean, raw bitstream in this layer from the physical layer. To give the network layer a frequent change of bitstreams, the data link layer divides the bitstreams into frames.
Error Control
It involves sending control frames for acceptance and putting frames in a sequence. A noisy channel can avoid scanning bits, dropping bits from frames, adding particular bits to frames, the final sinking of frames and more.
Flow Control
The data link design, which controls the cost of data communication between two source and destination hosts, has yet another fundamental flaw. Data packets will be dropped at the receiver end if there is a speed conflict between the source and destination hosts when sending and receiving data.
Sequence Integrity
Data bits are sent to the physical layer by the data link layer in the same order that they were received from the network layer, supporting the data bits sequence. Over the data link connections, it supports a dependable share of data link service data unit (DLSDU).