Intro to Computer Network📶
Computer networking is the technique of linking computers to communicate and exchange data with one another. A computer network typically consists of two or more computers. It allows users to converse more effectively.
OSI Model
Initially, computer networks had a set of hardware-dependent standards and norms. Each company created its communication protocols for their networks. Earlier communication protocols of this type included SNA (Systems Network Architecture) by IBM, DNA (Digital Network Architecture) by DEC (Digital Equipment Corporation), BNA (Burroughs Network Architecture) by Burroughs Incorporation, DSN (Distributed Systems Network) by Hewlett Packard, and PRIMENET (Prime Computers Network) by Prime Incorporation. The fundamental issue with this technique was that one network's communication protocols were incompatible with all other networks. The standards for the same network architecture have remained consistent over time.
For example, previous versions of SNA were not compatible with later versions.
After recognizing the issue, the International Organization for Standardization (ISO) established a subcommittee to develop a global standard for network topologies. The Open System Interconnection (OSI) paradigm is the product of recommendations made by this subcommittee. It serves as a framework for the creation of standards for tying disparate computers together in packet-switching networks. Consequently, any two heterogeneous computers, anywhere in the globe, could easily communicate with one another thanks to standardized OSI protocols.
TCP/IP Model
The Transmission Control Protocol/Internet Protocol paradigm (TCP/IP) is a fundamental idea in computer networking. It is a layered architecture that specifies how data is packaged and delivered over networks such as the Internet. Consider it a set of rules that allow diverse network devices to connect.
The model consists of five main layers, each with specific functions:
1. Application Layer: It defines the common communication protocols and interface mechanisms used by hosts in a communication network. It employs protocols like HTTP, SMTP, and Ex-Browser.
2. Transport Layer: Determines which client and server programs are supposed to get that info. It employs protocols such as TCP/UDP.
3. Network Layer: This allows separate networks to communicate with one another via routers, and it transmits data across network groups. It uses the IP protocol.
4. Data Link Layer: Responsible for creating a common way to read these signals so that network devices can communicate. It employs technologies such as Ethernet and WIFI.
5. Physical Layer: Represents the physical equipment used to link computers. Ex- cables and connectors
Physical Layer1️⃣
The physical layer transports raw bit streams between two nodes by transforming a series of binary digits into an electric signal based on whether the nodes are connected via a cable connection or fibre—spells and built microwave radio circuits, respectively. Physical layer protocols determine electrical features such as signals, light signals, or electromagnetic signals, depending on which o and 1 are used, how many bits may be delivered per second, and whether transmission can occur only in one direction, or in both directions at the same time. They also deal with mechanical aspects such as the size and voltage of connecting connections, the number of pins in plugs, and the function of each one. RS232-C is a widely used physical layer standard for serial communication lines.
Data Link Layer2️⃣
The physical layer transmits data between two nodes as raw bits. The data-link layer detects and corrects any error in transmitted data. For this, it partitions a raw bit stream of the physical layer into frames and performs error detection and correction for each frame independently. It also performs flow control of frames between two nodes to ensure that a sender does not flood a receiver with data by sending frames at a rate faster than the receiver can process
Network Layer3️⃣
The network layer sets up a logical communication path between two nodes. It encapsulates frames into packets and decides their transmission path from one node to another by using a high-level addressing and routing scheme. That is, routing is the primary job of the network layer, and the routing algorithm forms the main part of network layer protocols. Two popular network layer protocols are the X.25 Protocol and the Internet Protocol (called IP).
Notice that the network layer functions are primarily required in WANs. In a single LAN, the network layer is largely redundant because a LAN transmits packets directly from any node on the network to any other node.
Transport Layer4️⃣
The transport layer accepts messages of any length from the session layer, segments them into packets, sends them to the network layer for transmission, and then reassembles them at the destination. Some packets may be lost on their trip from sender to receiver, and depending on the routing algorithms employed at the network layer, packets may arrive at the destination in a different order than they were sent. Transport layer protocols contain tools for dealing with packets that have been lost or are out of sequence. The transport layer issues a sequence number to each packet and uses these numbers to detect lost packets and rebuild message packets in the correct sequence. TCP and UDP are the two most often used transport layer protocols.
Session Layer5️⃣
The session layer allows for the establishment, maintenance, and termination of a dialogue or session between two end users. It enables communicating parties to verify each other before initiating a dialogue session. It defines the dialogue type (one-way, two-way alternative, or two-way simultaneous) and starts a dialogue session if the message is a connection request message. It also includes a priority management service, which is useful for prioritizing critical and time-sensitive messages above less important messages.
Presentation Layer6️⃣
The presentation layer provides facilities to convert message data into a form that is meaningful to communicating application layer entities. For this, it may perform on message data such transformations as encoding and decoding, code conversion, compression and decompression, encryption and decryption, depending on an application's requirements.
Application Layer7️⃣
The layer that allows understandable communication between network applications. It is a collection of miscellaneous protocols for various commonly used applications such as electronic mail, file transfer, remote login, remote job entry, and schemas for distributed databases. Protocols here used are HTTP, SMTP, FTP, etc. for various purposes.
Network Security
Network security is like a digital fortress protecting your network and the data flowing through it. It encompasses a variety of practices, tools, and technologies aimed at achieving three main goals:
Confidentiality: Ensuring only authorized users can access sensitive information on the network. Imagine a vault with a complex lock system.
Integrity: Making sure data remains unaltered and hasn't been tampered with during transmission or storage. Think of a document with a digital signature to verify its authenticity.
Availability: Guaranteeing authorized users have consistent and reliable access to network resources. This is like having a well-maintained bridge for smooth traffic flow.
Network Troubleshooting
Network troubleshooting is the process of discovering and fixing issues that are preventing your network from functioning properly. It's like being a network detective and discovering out why things aren't operating properly.
Here's a typical troubleshooting approach:
Identify the problem: Slow internet, connection drops, and unavailable resources are all signs of a network problem.
Gather information: To identify the source, check device connectivity, error messages, and network settings.
Isolate the problem: Is the problem limited to a single device or does it affect the entire network? Consider systematically narrowing down the culprits.
Test and fix: Potential remedies include restarting devices, checking cable connections, and modifying setups.
Verify and document: Once the problem has been fixed, confirm that everything is working properly and maintain a record for future reference.
Conclusion
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