Computer networks are the basis of communication in IT. They are used in a huge variety of ways and can include many different types of network. A computer network is a set of computers that are connected together so that they can share information. The earliest examples of computer networks are from the 1960s, but they have come a long way in the half-century since then.
How Computer Networks Are Evolving ?
Modern-day networks deliver more than connectivity. Organizations are embarking on transforming themselves digitally. Their networks are critical to this transformation and to their success. The types of network architectures that are evolving to meet these needs are as follows:
• Software-defined (SDN): In response to new requirements in the "digital" age, network architecture is becoming more programmable, automated, and open. In software-defined networks, routing of traffic is controlled centrally through software-based mechanisms. This helps the network to react quickly to changing conditions.
• Intent-based: Building on SDN principles, intent-based networking (IBN) not only introduces agility but also sets up a network to achieve desired objectives by automating operations extensively, analyzing its performance, pinpointing problematic areas, providing all-around security, and integrating with business processes.
• Virtualized: The underlying physical network infrastructure can be partitioned logically, to create multiple "overlay" networks. Each of these logical networks can be tuned to meet specific security, quality-of-service (QoS), and other requirements.
• Controller-based: Network controllers are crucial to scaling and securing networks. Controllers automate networking functions by translating business intent to device configurations, and they monitor devices continuously to help ensure performance and security. Controllers simplify operations and help organizations respond to changing business requirements.
• Multidomain integrations: Larger enterprises may construct separate networks, also called networking domains, for their offices, WANs, and data centers. These networks communicate with one another through their controllers. Such cross-network, or multidomain, integrations generally involve exchanging relevant operating parameters to help ensure that desired business outcomes that span network domains are achieved.
What Do Networks Do?
Computer networks are used to carry out a large number of tasks through the sharing of information.
Some of the things that networks are used for include:
• Communicating using email, video, instant messaging and other methods
• Sharing devices such as printers, scanners and photocopiers
• Sharing files
• Sharing software and operating programs on remote systems
• Allowing network users to easily access and maintain information
Types of Network
There are many different types of network, which can be used for different purposes and by different types of people and organization. Here are some of the network types that you might come across:
1. Local Area Networks (LAN)
A local area network or LAN is a network that connects computers within a limited area. This might be in a school, an office or even a home.
2. Personal Area Networks (PAN)
A personal area network is a network that is based on an individual's workspace. The individual's device is the center of the network, with other devices connected to it. There are also wireless personal area networks.
3. Home Area Networks (HAN)
A home area network connects devices within a home environment. It might include personal computers, tablets, smartphones, printers, TVs and other devices.
4. Wide Area Networks (WAN)
A wide area network is a network that covers a larger geographical area, usually with a radius of more than a kilometer.
5. Campus Networks
A campus network is a LAN or set of connected LANs which is used by a government agency, university, corporation or similar organization and is typically a network across a set of buildings that are close together.
6. Metropolitan Area Networks (MAN)
Metropolitan area networks are networks that stretch across a region the size of a metropolitan area. A MAN is a series of connected LANs in a city, which might also connect to a WAN.
7. Enterprise Private Networks
An enterprise private network is used by a company to connect its various sites so that the different locations can share resources.
8. Internetworks
Internetworks connect different networks together to build a larger network. Internetworking is often used to describe building a large, global network.
9. Backbone Networks (BBN)
A backbone is a part of a network that connects different pieces and provides a path for information to be exchanged.
10. Global Area Networks (GAN)
A global area network is a worldwide network that connects networks all over the globe, such as the internet.
Network Protocols
Network Protocols are a set of guidelines governing the exchange of information in a simple, dependable and secure way. Network protocols are formal standards and policies comprised of rules, methodology, and configurations that define communication between two or more devices over a network. To effectively send and receive information, devices on the two sides of a communication exchange must follow protocols.
• Network Time Protocol:
• Network Time Protocol (NTP) is a protocol that synchronizes the clocks of computer systems over data networks. NTP was designed by David L. Mills. NTP permits network devices to synchronize their time settings with the NTP server. NTP is one of the most established internet protocols in current use.
• Domain Name System:
• DNS resolves a Uniform Resource Locator or website address to the IP address of the site. When users type a web address into the address bar they rely on DNS servers to resolve the actual IP address of that destination. DNS translates domain names to IP addresses.
• Routing Information Protocol:
• It constrains the number of hops permitted in a path on a network from the source device to the destination. The maximum number of hops permitted for RIP is fifteen. It is a routing protocol used to exchange routing information. It figures the best route based on hop count. It actualizes the split horizon, route poisoning and, holddown mechanisms.
• Dynamic Host Control Protocol:
• Dynamic Host Control Protocol (DHCP) uses a server to allocate an IP address and other configuration information to network devices. As a result, the device is getting a permission slip from the DHCP server to use the network. DHCP enables users to send a request to the DHCP server whenever they connect to a network. The server recognizes by providing an IP address to the user. DHCP is also known as RFC 2131.
TILL NOW WE HAVE GONE THROUGH A LOT OF THINGS AND NOW WE WILL TALK ABOUT SOME HARDWARE COMPONENTS USED IN NETWORKING............. :)
1. Network Cables :
Network cables are used to connect computers. The most commonly used cable is Category 5 cable RJ-45.
2. Distributors :
A computer can be connected to another one via a serial port but if we need to connect many computers to produce a network, this serial connection will not work.The solution is to use a central body to which other computers, printers, scanners, etc. can be connected and then this body will manage or distribute network traffic.
3. Router :
A router is a type of device which acts as the central point among computers and other devices that are a part of the network. It is equipped with holes called ports. Computers and other devices are connected to a router using network cables. Now-a-days router comes in wireless modes using which computers can be connected without any physical cable.
4. Network Card
Network card is a necessary component of a computer without which a computer cannot be connected over a network. It is also known as the network adapter or Network Interface Card (NIC). Most branded computers have network card pre-installed. Network cards are of two types: Internal and External Network Cards.
Internal Network Cards
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Motherboard has a slot for internal network card where it is to be inserted. Internal network cards are of two types in which the first type uses Peripheral Component Interconnect (PCI) connection, while the second type uses Industry Standard Architecture (ISA). Network cables are required to provide network access.
External Network Cards
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External network cards are of two types: Wireless and USB based. Wireless network card needs to be inserted into the motherboard, however no network cable is required to connect to the network.
5. Universal Serial Bus (USB)
USB card is easy to use and connects via USB port. Computers automatically detect USB card and can install the drivers required to support the USB network card automatically.
TILL NOW WE SAW MANY THINGS RELATED TO NETWORKING AND HARDWARE ALSO BUT NOW I WILL TELL A VERY IMPORTANT THING THAT IS VERY USEFULL IN NETWORKING........... :)
The OSI Model
The OSI Model (Open Systems Interconnection Model) is a conceptual framework used to describe the functions of a networking system. The OSI model characterizes computing functions into a universal set of rules and requirements in order to support interoperability between different products and software. In the OSI reference model, the communications between a computing system are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
Created at a time when network computing was in its infancy, the OSI was published in 1984 by the International Organization for Standardization (ISO). Though it does not always map directly to specific systems, the OSI Model is still used today as a means to describe Network Architecture.The 7 Layers of the OSI Model
Physical Layer :
The lowest layer of the OSI Model is concerned with electrically or optically transmitting raw unstructured data bits across the network from the physical layer of the sending device to the physical layer of the receiving device. It can include specifications such as voltages, pin layout, cabling, and radio frequencies. At the physical layer, one might find “physical” resources such as network hubs, cabling, repeaters, network adapters or modems.Data Link Layer
At the data link layer, directly connected nodes are used to perform node-to-node data transfer where data is packaged into frames. The data link layer also corrects errors that may have occurred at the physical layer.
The data link layer encompasses two sub-layers of its own. The first, media access control (MAC), provides flow control and multiplexing for device transmissions over a network. The second, the logical link control (LLC), provides flow and error control over the physical medium as well as identifies line protocols.
Network Layer :
The network layer is responsible for receiving frames from the data link layer, and delivering them to their intended destinations among based on the addresses contained inside the frame. 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.
Transport Layer :
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. One of the most common examples of the transport layer is TCP or the Transmission Control Protocol.
Session Layer :
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.
Presentation Layer :
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.
Application Layer :
At this layer, both the end user and the application layer interact directly with the software application. This layer sees network services provided to end-user applications such as a web browser or Office 365. The application layer identifies communication partners, resource availability, and synchronizes communication.Studying computer networks
A solid math background is valuable, like all the other computer science and engineering fields. In addition to Calculus, important tools in computer networking and communications include the following:
• Linear algebra
• Probability and statistics
• Differential equations
• Numerical analysis
Good programming skills are also very important. Although a good programming background may not be necessary for some of the topics under networking (e.g., low-level communications, hardware issues), networking protocols and software require a solid programming background.
Most of the time, students have to develop skills in a new paradigm of programming: distributed programming. In distributed programming, replicas of the same of code run on different machines but work collectively to do a common task. This may sound like parallel programming, but it's not quite the same. Most of the time, code replicated over the network treats each other as peers and exchanges messages to proceed on a common task, e.g., transferring data from one machine to another.
A solid capability for abstract thinking is also essential for networking, like most other computer science fields. Networking typically involves a layered architecture where each layer is an abstraction of services to layer above. Writing code for networking software involves a good deal of abstraction.
Now we have reached the end of the article and i will just put the basic keys that you should remember in networking......keep learning and give comments about what you all want next.............. :)
Key Networking Terms
Open system: an open system is connected to the network and prepared for communication.
Closed system: a closed system is not connected to the network and so can't be communicated with.
IP (internet protocol) address: the network address of the system across the network, which is also known as the Logical Address).
MAC address: the MAC address or physical address uniquely identifies each host. It is associated with the Network Interface Card (NIC).
Port: a port is a channel through which data is sent and received.
Nodes: nodes is a term used to refer to any computing devices such as computers that send and receive network packets across the network.
Network packets: the data that is sent to and from the nodes in a network.
Routers: routers are pieces of hardware that manage router packets. They determine which node the information came from and where to send it to. A router has a routing protocol which defines how it communicates with other routers.
Network address translation (NAT): a technique that routers use to provide internet service to more devices using fewer public IPs. A router has a public IP address but devices connected to it are assigned private IPs that others outside of the network can't see.
Dynamic host configuration protocol (DHCP): assigns dynamic IP addresses to hosts and is maintained by the internet service provider.
Internet service providers (ISP): companies that provide everyone with their internet connection, both to individuals and to businesses and other organizations.
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