What is Data Link Layer – Layer 2 of The OSI Model?
Before the data is ready for transmission over the network channel, processing and converting the data with the specified services is necessary to reach proper transmission standards. This task is handled by the “Data Link Layer in the OSI Model.” In this article, we will be briefed on the terms and information related to the working and functioning of the data-link layer.
What is the Data Link Layer?
The data link layer is the protocol layer in a program that handles how data moves in and out of a physical link in a network. It is Layer 2 in the Open Systems Interconnection (OSI) architecture model for a set of telecommunication protocols.
The data link layer encodes, decodes, and organizes data bits in the data link layer before it transports the data bits as frames between two adjacent nodes on the same local area network (LAN) or wide area network. It also determines how devices recover from collisions that might occur when nodes attempt to send frames at the same time.
It has two sublayers: the logical link control (LLC) sublayer and the media access control (MAC) sublayer.
Working of the Data Link Layer
The data flow between the data-link layer and other layers in the OSI Model, i.e., to begin with, the network layer will share the data packets with the data-link layer.
The data-link layer handles these data packets by integrating them with the frame structure. The frame acts as a header for the data packet, containing information about the destination address, sender address, and other related services.
The final data format in the data-link layer is known as the data frame, which is then transmitted to the physical layer of the OSI Model.
Functionality of Data Link Layer
Data link layer does many tasks on behalf of the upper layer. These are:
- Framing – It takes packets from the Network Layer and encapsulates them into Frames. Then, it sends each frame bit-by-bit on the hardware. At the receiver’s end, the data link layer picks up signals from hardware and assembles them into frames.
- Addressing – It provides a layer-2 hardware addressing mechanism. The hardware address is assumed to be unique on the link. It is encoded into hardware at the time of manufacturing.
- Synchronization – When data frames are sent on the link, both machines must be synchronized to transfer to take place.
- Error Control – Sometimes signals may encounter problems in transition and the bits are flipped. These errors are detected and attempted to recover actual data bits. It also provides an error reporting mechanism to the sender.
- Flow Control – Stations on the same link may have different speeds or capacities. Data link layer ensures flow control that enables both machines to exchange data at the same speed.
- Multi-Access – When a host on the shared link tries to transfer the data, it has a high probability of collision. Data link layer provides mechanisms such as CSMA/CD to equip the capability of accessing shared media among multiple Systems.
Conclusion
In conclusion, the Data Link Layer is essential for ensuring data is transferred reliably and accurately across a network. It handles error detection and correction, manages data frame sequencing, and provides access to the physical network. By organizing data into frames and controlling how devices on the network communicate, the Data Link Layer plays a crucial role in maintaining smooth and efficient network operations.