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The Internet and every other type of computer network possess a layered architecture. Networks are central to information processing and technology, & the architecture dictates how data is shared across the Web. There are different networking models, specific networking criteria, and categories. We have local area networks & wide area networks that can be implemented using different kinds of network models, physical structures & topologies. Sometimes, students look for Computer network assignment help to complete their networking paper on time.
The virtual representation of modern networks will reveal a layered architecture, wherein different network layers in a network's architecture manage various aspects involved in the exchange & sharing of data.
Let’s have a closer look.
A network is an amalgamation of different hardware and software. Physical equipment transports the signal while the software ensures reliable & secure data transfer & associated services. It is akin to how computers solve a particular task; hardware and software together manipulate & process data as required.
The layered nature of network architecture is crucial to achieving reliable, secure, and fast information exchange. Each layer carries out a particular task and contributes to the overall flow of information. Moreover, layers at both the sending and receiving employ the services of the layer immediately before.
For example, in networks, sending an e-mail is decomposed into a series of tasks, each carried out by a software package that guides particular hardware to do something. And, each software package avails the services of another software package in the layer above. Through all such interactions, networks can guide a set of electrical signals from one node to another.
Two of the most prominent layered network models that form the basis of every computer network system are the OSI & the TCP/IP model. The OSI model is the basis of the TCP/IP model. So we start with the OSI model.
OSI vs. TCP/IP Source: www.researchgate.net
The International Standards Organization, a multinational organization, is a globally recognized body that was the first to establish an international standard for network communications. Known as the Open Systems Interconnection architecture, it creates a set of protocols for designing computer networks. The OSI model possesses a layered architecture and acts as a global standard for facilitating communications between different systems without concern for the underlying logic & architecture.
The OSI model is not a protocol but a layered framework for network systems, allowing seamless communication between computer systems. There are seven distinct but interconnected layers, each with a specific role to play in the process of moving data & information across a particular network. Therefore, network engineers must possess solid ideas of all the layers within the model for a thorough understanding of network operations.
One key thing to note is that the layers in the OSI model are all virtual. The OSI model comprises seven distinct hierarchical layers, namely,
Data Link Layer
Many of such intermediate nodes generally involve only a few layers of the OSI model, with only end nodes possessing all the different layers.
To pursue a career in networking, you need a solid understanding of all layered architectures and the functions & constituents of every single layer. Look for computer network assignment help online if you need professional assistance.
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Let's look at each of the layers involved in the OSI model in detail.
The physical layer manages the transport of electrical signals across the physical medium. It deals with the mechanical and electrical specifications of the physical interfaces & the transmission medium. This layer also defines the different procedures and functions that the physical devices concerned with signal transmission must perform.
The physical layer is concerned with the following:
The physical characteristics of the medium and associated interfaces
The way bits are represented.
Bit transmission rates
Synchronization and network topology or configuration
The transmission modes
The layer directly above the network layers is the data link layer.
The data link layer is tasked with transforming the physical transmission media (an unreliable transmission facility) into a reliable data link. It provides error-control to the physical layer and is generally concerned with the following:
Framing, wherein the layer divides the continuous stream of bits into distinct manageable units of data called frames.
Physical addressing in which the layer adds a header to the frame that defines the sender and receiver of a particular frame.
The data link layer also controls the data flow from the sender to the receiver and imposes a flow control mechanism.
Error control is another chief responsibility of the data link layer, through which it adds reliability by detecting lost, damaged, or duplicate frames. In addition, the layer adds a trailer to the end of the frame.
Another service offered by the data link layer is access control, wherein its protocols control which devices have control over a link at a particular moment.
The network layer controls how data reaches from the source to the destination across multiple data links. The critical distinction between the data link layer and the network layer is that while the data link layer controls the data transmission between the same network, the network layer controls data transfer across different networks.
When the sender and receiver are on two different networks, the network layer makes successful data transmission possible across networks.
The two key objectives of the network layer are as follows.
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While physical addressing of the data frames is handled by the data link layer; however, they are not enough when a data frame exits the boundaries of the local network. Therefore, logical addresses distinguish source and destination across different networks.
For logical addressing, the network layer adds a header to the entirety of the data packet that comes from the upper layer. This header includes the logical addresses of the source and destination.
Interconnection among different networks makes routing of data frames necessary. Routers, also known as switches, guide data frames from their source to their destination.
This particular layer is responsible for the process-to-process delivery of data. In any computer system, applications run processes with permission from the operating system to access the system's network capabilities.
The transport layer distinguishes the nature of the information contained in a data frame. It also oversees error and flows control to ensure that information reaches the correct process.
Key responsibilities of the transport layer are:
Service point addressing, wherein the layer ensures proper data delivery from a particular process of the sender to the targeted process of the receiver;
Segmentation & Reassembly involves reconstructing the original message correctly upon arrival.
Flow, error, and connection control are the other tasks of this layer.
In the TCP/IP model, the Transmission Control Protocol operates at this level.
The session layer acts as a network’s dialog controller. It manages and synchronizes interaction between two processes on two interacting systems.
Dialog Control: The session layer allows and controls the communication between two systems/processes.
Synchronizationalso ensures synchronization within the data communication streams, ensuring data integrity and reliability.
This particular layer concerns itself with the meaning and logic in the information transmitted. Responsibilities of the presentation layer include:
The application layer offers an interface for accessing the network resources. For example, the browser, e-mail database management services, remote access applications, etc.- the application layer encompasses them all. Tasks of the application layer involve:
Virtual network logging: This software emulation of the network's physical terminal allows users to log on to a remote host. The software makes the host believe it is interacting with one of its own.
File transfer & management: Offers a user interface for accessing, managing, and transferring files.
Mail & directory Services: The application layer oversees access to mailing and database services.
The TCP/IP model, the underlying framework of the Internet, is derived from the OSI model. We round up this write-up with a concise look at the architecture that underlies the Internet.
The Transmission Control Protocol/Internet Protocol model has four distinct layers, namely,
The network access layer combines the functions of both the physical layer & the data link layers of the OSI model. It handles the physical infrastructure and monitoring of electrical signals across copper cables, fiber optic lines, and any wireless medium. Network access layers also monitor the technical aspects of the infrastructure, such as codes within network cards & device drivers that transform digital data into transmittable signals.
The Internet layer essays the role of the network layer in the OSI model. Roles and responsibilities include controlling, routing, and reassembling data packets sent across a network.
The transport layer is responsible for ensuring the reliability of a data connection between two devices. This layer divides a particular data stream into distinct packets and provides proper sending/reception of messages.
The application layer refers to all the different processes &application that allows users to access network resources. The application layer fulfills the responsibilities of the session, presentation, and application layers of the OSI model.
TCP, the transmission control protocol, and IP, the Internet protocol, are two distinct protocols that operate at the transport & network layers. The most prominent difference between TCP & IP is their role in the entire data transmission process. IP operates at the network layer and determines the logical or IP address of the communicating machines, while TCP ensures accurate & reliable transmission of information.
So, when you send e-mails, the IP sorts them as per the IP address of their destination, while TCP sends & receives them. TCP/IP works in tandem with numerous other protocols such as the Hyper Text Transfer Protocol, Simple Mail Transfer Protocol, and File Transfer Protocol, etc. (these three, in particular, operate at the application layer). Together, they make the Internet operational.
And that's all the space we have for today. Hope this was an informative read for everyone.
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