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App Security Edge Security DDoS Essentials. Connection Optimization Essentials. Attack Tools Essentials Threats. In other words, the data-link layer is embedded as software in the NIC which provides a means for data transfer from one computer to another via a local media.
Thus, the data-link layer facilitates the transmission of data within the same network only. The source and destination MAC addresses are included in the data header file by the data-link layer. At the sender's side, it receives the data in the form of packets from the network layer and converts it into smaller forms, called the data frame. At the receiver's side, it converts the data frame into packets for the network layer.
The Network layer is the third layer of the OSI model. It mainly performs the transmission of data from one computer to another in different networks. This layer may not be so beneficial if we are transmitting the data in the same network. The network layer performs logical addressing IP addressing of the data. The source and destination IP addresses are included in the data header file by the network layer.
The data is in the form of packets in this layer. At the sender side, the network layer breaks the data segments received from the upper layer into smaller units, called data packets. Similarly, at the receiver's side, it reassembles the data packets into segments for the upper layer, i.
Routers are mainly used in the network layer for routing purposes. The Transport layer is the fourth layer of the OSI model. It is mainly responsible for the process-to-process delivery of the data. It performs flow and error control in the data for its proper transmission. The transport layer controls the reliability of communication through various functionalities. The network layer finds the destination by using logical addresses, such as IP internet protocol.
At this layer, routers are a crucial component used to quite literally route information where it needs to go between networks. The transport layer manages the delivery and error checking of data packets. It regulates the size, sequencing, and ultimately the transfer of data between systems and hosts. The session layer controls the conversations between different computers. A session or connection between machines is set up, managed, and termined at layer 5.
Session layer services also include authentication and reconnections. The presentation layer formats or translates data for the application layer based on the syntax or semantics that the application accepts. Because of this, it at times also called the syntax layer. This layer can also handle the encryption and decryption required by the application layer.
At this layer, both the end user and the application layer interact directly with the software application. In its most basic sense, this layer is responsible for packet forwarding, including routing through different routers. You might know that your Boston computer wants to connect to a server in California, but there are millions of different paths to take. Routers at this layer help do this efficiently. The Data Link Layer provides node-to-node data transfer between two directly connected nodes , and also handles error correction from the physical layer.
In the networking world, most switches operate at Layer 2. Some switches also operate at Layer 3 in order to support virtual LANs that may span more than one switch subnet, which requires routing capabilities. At the bottom of our OSI model we have the Physical Layer, which represents the electrical and physical representation of the system.
This can include everything from the cable type, radio frequency link as in a Wi-Fi network , as well as the layout of pins, voltages, and other physical requirements. After that, you hear about the OSI model when vendors are making pitches about which layers their products work with. If you can understand the OSI model and its layers, you can also then understand which protocols and devices can interoperate with each other when new technologies are developed and explained.
If you need to memorize the layers for a college or certification test, here are a few sentences to help remember them in order.
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