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OSI Model (Open Systems Interconnection Model)

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  Networking Model – Networking models categorize and provide a structure for networking protocols and standards. Networking Protocols/standards – A set of rules defining how network devices and software should work. OSI Model – 1.       OSI stands for Open Systems interconnection model. 2.       A conceptual model that categorizes and standardizes the different functions in a network. 3.       Created by the “International Organization for Standardization” (ISO). 4.       Functions are divided into 7 layers. 5.       These layers work together to make the network work. 6.       Data is encapsulated at one end and de-encapsulated at other end with the help of OSI model layers. 7.       Upper layers (Application, presentation, and session) prepare data and lower layers (transport, network, data link, physical) sent it over the network.   7. Application 6. Presentation 5. Session 4. Transport 3. Network
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Computer Networking

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  Computer Network – A computer network is a digital communications network which allows nodes to share resources. Types of nodes – Router, Switch, Firewall, Server, Client Clients – A client is a device that accesses a service made available by server. Server – A server is a device that provides functions or services for clients. Switches – 1.       Provides connectivity to hosts within the same LAN (Local Area Network). 2.       Switches do not provide connectivity between different LAN’s/ over the internet. 3.       Switches have many network interfaces/ports for end hosts to connect to (usually 24+). 4.       Catalyst 9200, Catalyst 3650 are some switches we use in network. Routers – 1.       Provides connectivity between LANs. 2.       Hence used to send data over the internet. 3.       Routers have fewer network interfaces than Switches. 4.       ISR1000, ISR900, ISR 4000 are some routers we use in network. Firewalls – 1.       Firewalls monitor a
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Basics of Linux

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  Shell – Shell is a program that takes command from the keyboard and gives them to operating system to perform. We also called it as a command line interface (CLI). Terminal – Terminal a tool which you can used to pass a shell command. It’s lets you interact with shell. File System – File system in Linux arranged in a hierarchical directory structure like tree diagram. Root ( / ) is a main directory under which we have other directories. Below are the directories under root file system, Basic Commands - $ PWD – To check present working Directory. $ cd – Change directory $ ls – List the files or directories.  
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History of Linux

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  History of Linux – In 1964 Bell Laboratory stats a project in which they want to develop multiuser operating system. Dennis Ritchie and Ken Thompson was part of the project. Then in 1969 Bell Laboratory withdraw the project due to lack of results. But Dennis Ritchie and Ken Thomson started the project again from the beginning and developed a operating system called UNICS/UNIX (Uniplexed Information and computing services), and the source code of this operating system was freely available. Then in 1975 UNIX version 6 gain popularity and some companies started taking benefit of it and developed their own flavours of UNIX. IBM developed AIX, Sun system developed Sun Solaris, Apple developed MAC OS, HP developed UX. But all these operating system was not freely available, at that time Linus Torvalds was student and he wants to research on UNIX operating system and operating system was not freely available at that time so he started developing his own flavour of UNIX called Linu
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What is Operating System?

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  What is operating system -  An operating system is the software that manages the computers hardware and provides a convenient and safe environment for running programs. It acts as an interface between programs and hardware resources that these programs access (like memory, hard disk and printer). It is loaded into memory when a computer is booted and remains active as long as the machine is up. Key Features of an operating system -  The operating system allocates memory for the program and loads the program in it. It also loads the CPU registers with control information related to the program. The registers maintain the memory locations where each segment of a program is stored. The instructions provided in the program are executed by CPU. The operating system keeps track of the instructions that was executed last. This enables it to resume a program if it had to be taken out of the CPU before it completed execution. If the program needs to access the hardware, it makes a call to the
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TCP/IP Suite

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TCP/IP Suite – 1.     Conceptual model and set of communications protocols used in the internet and other networks. 2.     Known as TCP/IP because those are two of the fundamental protocols in the suite. 3.     Developed by the United States Department of Defense through DARPA (Defense Advanced Research Projects Agency). 4.     Similar structure to the OSI model, but with fewer layers. 5.     This is the model in use in modern networks. 6.     Note – The OSI model still influences how network engineers think and talk about networks.   4. Application 3. Transport 2. Network 1. Data link    
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Modulation

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Introduction -  Hi guys, Have you heard about modulation, what is mean by modulation, what are different types of modulation? I am sure you have if you are Engineering student.  So, in this blog we will discuss basics of modulation. So, our human voice signal contains the frequency up to 3 kHz and entire audible spectrum is between 20 Hz to 20 kHz. These low frequency signal called Baseband signal. Baseband signal can not be transmitted over long distance, we need to convert into high frequency signal to transmit over long distance. This high frequency signal is called Carrier signal. What is Modulation?   Modulation is a process of converting baseband signal into a signal that varies with one of its properties like amplitude, frequency, phase. We obtain modulated signal by adding carrier signal to baseband signal. Why we need Modulation? Reduce the antenna size – So, how we can reduce the size of the antenna, we will understand this point with the help of some basic calculation. L
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