What are the Network Devices

Network consist of different devices each has its own function. some of the network devices are PC,Server,Network Card ( NIC ),Hub,Bridge, Repeater, Switch,Brouter,Router,Firewall,Ethernet cable,Fiber Cable etc... 

PC:- Personal Computer  is intended to be operated directly by an end-user for data processing, Software applications   development, Personal computers may be connected to a Local Area Network ( LAN ), either by a cable or a wireless connection.

Personal Computer

SERVER:- A server is a computer that provides services to other computers . it is dedicated to running one or more services.Depending on the computing service that it offers it could be a database server, file server, mail server, print server, web server, gaming server, or some other kind of server.

Server

Network Interface Card ( NIC ):- is also commonly referred to as an Ethernet card and network adapter and is an expansion card that enables a computer to connect to a network such as a home network or the Internet using an Ethernet cable with a RJ-45 connector.

Network Interface Card

HUB:- A Hub connects all the node ( work stations )  of a network using Twisted Pair Ethernet cables. In a Hub, the signals received on one port are transmitted to all other ports, and vice versa. All nodes  connected using a Hub can listen to one another all the time. If two or more workstations try to transmit during the same time, it results in collision of signals, and the signals are lost altogether.

HUB

BRIDGE:- Bridges are used to divide larger networks into smaller sections. They do this by sitting between two physical network segments and managing the flow of data between the two.By looking at the MAC address of the devices connected to each segment, bridges can elect to forward the data (if they believe that the destination address is on another interface), or block it from crossing (if they can verify that it is on the interface from which it came).

BRIDGE

SWITCH:- A network switch is networking device that connects network devices or network segments. Devices connect to switches via twisted-pair cabling, one cable for each device. switch receives a message from any device that connects  to it and transmit the message to only to that device for the message was meant.  It does this by learning the MAC address of the devices attached to it, and then by matching the destination MAC address in the data it receives. this make switch more intelligent than hub.Switch maintain CAM ( Content addressable memory )table that maps individual MAC address on the network.

SWITCH

REPEATER:-Network repeaters regenerate incoming electrical, wireless or optical signals. With physical media like Ethernet or Wi-Fi, so that signal can cover longer distance. Data transmissions can only span a limited distance before the quality of the signal degrades.

REPEATER

ROUTER:- A Router is a device that connects Two or more different networks. it forwards the data packet between networks. When data comes form one network it reads the address information in the packet to determine its ultimate destination. Then using information in its routing table or routing policy it directs the packet to the next network on its journy. Routes some times called as gateways.

Functions of Router --

*Best path selection

*Packet switching

*Packet Forwarding

*Restrict Broadcasting

*Act as Gateway

ROUTER

Network Topology & Types

 A Topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines.

There are two basic categories of network typologies

1. Physical topologies
2. Logical topologies                                               

               

                 The shape of the cabling layout used to link devices is called the physical topology of the network. This refers to the layout of cabling, the locations of nodes, and the interconnections between the nodes and the cabling

                   

                 The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices. A network's logical topology is not necessarily the same as its physical topology.

Network  Topologies 

Bus Topology:- A bus topology creates a network by connecting 2 or more hosts to a length of coaxial backbone cabling. In this topology, a terminator must be placed on the end of the backbone coaxial cabling - in Michael Meyer's Network+ textbook, he commonly compares a network to a series of pipes that water travels through. Think of the data as water; in this respect, the terminator must be placed in order to prevent the water from flowing out of the network.

BUS TOPOLOGY

Ring Topology:- A ring topology (more commonly known as a token ring topology) creates a network by arranging 2 or more hosts in a circle. Data is passed between hosts through a 'token.' This token moves rapidly at all times throughout the ring in one direction. If a host desires to send data to another host, it will attach that data as well as a piece of data saying who the message is for to the token as it passes by. The other host will then see that the token has a message for it by scanning for destination MAC addresses that match its own. If the MAC addresses do match, the host will take the data and the message will be delivered.

RING TOPOLOGY

Star Topology:-A star topology creates a network by arranging 2 or more host machines around a central hub. A variation of this topology, the 'star ring' topology, is in common use today. The star topology is still regarded as one of the major network topologies of the networking world. A star topology is typically used in a broadcast  network, where a single information source communicates directly with multiple clients. An example of this is a radio station, where a single antenna transmits data directly to many radios.

STAR TOPOLOGY

Tree Topology:-A tree topology is so named because it resembles a binary tree structure from computer science. The tree has a "root" node, which forms the base of the network. The root node then communicates with a number of smaller nodes, and those in turn communicate with an even greater number of smaller nodes. An example of a tree topology network is the DNS system. DNS root servers connect to DNS regional servers, which connect to local DNS servers which then connect with individual networks and computers. For your personal computer to talk to the root DNS server, it needs to send a request through the local DNS server, through the regional DNS server, and then to the root server.this is the best example for tree topology.

TREE TOPOLOGY

Mesh topology:- A mesh topology creates a network by ensuring that every host machine is connected to more than one other host machine on the local area network. This topology's main purpose is for fault tolerance - as opposed to a bus topology, where the entire LAN will go down if one host fails. In a mesh topology, as long as 2 machines with a working connection are still functioning, a LAN will still exist.The mesh topology is still regarded as one of the major network topologies of the networking world.

MESH TOPOLOGY

Hybrid topology:- A hybrid topology, which is what most networks implement today, uses a combination of multiple basic network topologies, usually by functioning as one topology logically while appearing as another physically. The most common hybrid topologies include Star Bus, and Star Ring.

HYBRID TOPOLOGY

What is Internet

                      The Internet, sometimes called simply "the Net," is a worldwide system of computer networks - a network of networks in which users at any one computer can, if they have permission, get information from any other computer and sometimes talk directly to users at other computers.They are linked by a broad array of electronic, wireless and optical networking technologies.

According to Internet world stats, as of December 31, 2011 there was an estimated 2,267,233,742 Internet users worldwide. This represents 32.7% of the world's population.

Type of Network

1.Personal Area Network
  

        A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are printers, fax machines, telephones and scanners. The reach of a PAN is typically about 20-30 feet.

Personal Area Network

2.Local Area Network

    

         A local area network(LAN)is a network that interconnects computers in a limited area such as a home,    school, computer laboratory, or office building using network media. Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs.

Local Area Network 

3.Campus Area Network

               

         A campus area network known as (CAN) is A network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base.

Campus Area Network

4.Metropolitan Area Network

      

        A Metropolitan Area Network (MAN) is a network that connects two or more Local Area Networks or Campus Area Networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a Metropolitan Area Network.

Metropolitan Area Network

5.Wide Area Network

       A Wide Area Network (WAN)is which spans a large geographic area, such as a state, province or country. WANs often connect multiple smaller networks, such as local area networks (LANs) or metro area networks (MANs).

Wide Area Network

What Is Network ?

A computer network, or simply a network is a collections of computers and other other devices like switches,routers interconnected by communication medium such as copper,Cat-5,Fiber cables or Radio Frequency that allow sharing of resources of information

Network Engineer