Computer Networking Basics...


A network is a collection two or more standalone computers that communicate with one another over a shared network medium to share resource and information.

Networking Components:

Network Interface Cards: It allows a network capable device such as computer, printer etc to access a computer network.NIC Card Every NIC card has a unique MAC (media access control) address which is assigned to NIC Card for communications on the physical network segment.

Hubs: A hub is a device for connecting multiple ethernet cables to communicate and making a network segment.

Switches: A switch is a networking device that connects network segments or network devices. It forwards and filters datagrams (chunk of data communication) between ports based on the Mac-Addresses in the packets. It works faster thanSwitch hubs.

Routers: A router is a networking device that works on the basis of routing tables and routing policies configured by the programmer. A router has its own Processor, OS, memory etc.

Classifying Networks:

On the basis of scale or extent of reach of network:
LAN (Local Area Network): LANs are networks usually confined to a geographic area, such as a building, college or within a house to share information and resources. Speed of data transfer in LAN is very fast as compared to MAN and WAN.

MAN (Metropolitan Area Network): It refers to a network of computers with in a City or a Metropolitan area.

WAN (Wide Area Network): Wide Area Networking combines multiple LANs that are geographically separate by using private or public network transports (ISP).
• On the basis of hardware technology: Optical fiber, Ethernet, Wireless LAN.
• Functional relationship:

Client-Server: In a client/server network, all information and resources are used to store in a single central location like Server. Other client machines like computers used and access those resource from the server by network connection. It is used for some specific tasks like file sharing, print processing, Internet connectivity, e-mail service etc.

Peer-to-peer: The most basic way to connect multiple computers in a peer-to-peer network to allow multiple users to share information or resources. It is used to connect computers running on workgroup.


The OSI Model:
A network protocol defines rules and conventions for communication between network devices. There are seven layers in OSI Model: physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and the application layer. When data is transfer in packet format it has to pass all the seven layers to reach the destination.

Physical Layer: The physical layer, the lowest layer of the OSI model. It provides the hardware means of sending andOSI Layer receiving data on a carrier, including defining cables, cards and physical aspects. Protocols: ISDN.

Data Link Layer: At this layer, data packets are encoded and decoded into bits. The layer also determines the size and format of data sent. The data link layer provides error-free transfer of data frames from one node to another over the physical layer. Protocols: Logical Link Control, Media Access Control.

Network Layer: This layer determines how the data packets will travel through different networks. The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. Protocols: IP, ARP, RARP, ICMP, RIP.

Transport Layer: This layer allows data to be broken into smaller packages for data to be distributed and addressed to other nodes (workstations). Protocols: TCP, ARP, RARP, SPXNWLink, NetBIOS / NetBEUI.

Session Layer: The Session layer establishes, maintains, and manages the communication session between computers. Protocols: NetBIOSNames .

Presentation Layer: This layer is responsible to code and decode data sent to the destination or node.

Application Layer: This layer allows use an application that will communicate with the operation system of a node. Protocols: DNS, FTP, SMTP, MIME, NFS.


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