Networking

What Is Network?

A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

They are two very common types of networks include:

• Local Area Network (LAN)

• Wide Area Network (WAN)

You may also see references to a Metropolitan Area Networks (MAN), a Wireless LAN (WLAN), or a Wireless WAN (WWAN).

Fig. of Network

Local Area Network(LAN) :

• The local area network (LAN) is a network which is designed to operate over a small physical area network. A local area network is network that connects computers and devices in limited geographical area such as an office or campus, school, factory or a group of buildings,residence, laboratory its network equipment and interconnects locally managed. LANs are very widely used in a variety of applications.  

Fig. of LAN

Wide Area Network(WAN) :

• A wide area network (WAN) is a network that exists over a large-scale geographical area. A WAN connects different smaller networks, including local area networks (LAN) and metro area networks (MAN). This ensures that computers and users in one location can communicate with computers and users in other locations. WAN implementation can be done either with the help of the public transmission system or a private network.

Fig. of WAN

Common Network Components :

                                                                  There are a lot of different machines, devices, and media that make up our networks. Right now, I’m going to tell you about three of the most common: 

• Workstations
•  Servers 
•  Hosts

Workstations :

• A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating system. The term workstation has also been used loosely to refer to everything from a mainframe computer terminal to a PC connected to a network.

Fig. of Workstations

Servers :

• A server is an a computer program that accepts and responds to requests made by another program, known as a client.This architecture is called the client–server model, and a single overall computation is distributed across multiple processes or devices. Servers can provide various functionalities, often called "services", such as sharing data or resources among multiple clients, or performing computation for a client. A single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the same device or may connect over a network to a server on a different device.
• A Server are used to manage  network resources. For example, a user may setup a server to control access to a network, send/receive e-mail, manage print jobs, or host a website.
•  Here’s a list of common dedicated servers:

 File Server : 

                  A file Server is a computer responsible for the central storage and management of data files so that other computers on the same network can access them.

• A file server is a computer attached to a network that has the primary purpose of providing a location for shared disk access, i.e. storage of computer files. (such as documents, sound files, photographs, movies, images, databases, etc.)

Mail Server :

                       A mail server is an application that receives incoming e-mail from local users (people within the same domain) and remote senders and forwards outgoing e-mail for delivery. 

Print Server :

                       A print server, or printer server, is a device that connects printers to client computers over a network.A print server may be a networked computer with one or more shared printers.

Web Server :

                         A web server is a computer system that processes requests via HTTP, the basic network protocol used to distribute information on the World Wide Web.

Fax Server : 

                       A fax server is a system installed in a local area network (LAN) server that allows computer users who are attached to the LAN to send and receive fax messages. Fax messages can be stored as printable word processing, graphics, database, or spreadsheet files.

Application Server :

                           An application server is a program that handles all application operations between users and an organization's backend business applications or databases.

• An application server is a software framework that provides both facilities to create web applications and a server environment to run them.

Telephony Server :                             
                        The Telephony service (TS) implements Telephony Application Programming Interface (TAPI) services to support programs that effectively work the same way over intranets, the Internet, and traditional public phone networks.This Help file provides information for configuring and managing telephony servers and clients.

Remote-access Server :

                                 A remote access server (RAS) is a type of server that provides a suite of services to remotely connected users over a network or the Internet. It operates as a remote gateway or central server that connects remote users with an organization's internal local area network (LAN).

Hosts :
             A host is also known as "network host" is a computer or other device that communicates with other hosts on a network. Hosts on a network include clients and servers -- that send or receive data, services or applications.

Network Architecture: 

They are two very common types of Networks Architecture include:

 Peer-to-Peer

  Client/Server

Peer-to-Peer Networks :

                  A peer-to-peer(P2P) network is created when two or more PCs are connected and share resources without going through a separate server computer. A P2P network can be an ad hoc connection--a couple of computer connected via a Universal Serial Bus of transfer files.

Client/Server Networks :

                      A client–server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system. A server host runs one or more server programs which share their resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await incoming requests.

Physical Network Topologies :

                  The cabling layout used to link devices is the physical topology of the network. This refer to the layout of cabling, the location of nodes, and the interconnections between the nodes and the cabling. Token Ring is a logical ring topology, but is wired as a physical star from the media access unit. 

• Bus 

• Star 

• Ring 

• Mesh 

• Point-to-point 

• Point-to-multipoint 

• Hybrid

BUS :

              Alternatively referred to as a line topology, a bus topology is a network setup in which each computer and network device are connected to a single cable or backbone. 

Fig. BUS Topology

Advantages of bus topology :

• It works well when you have a small network.

• Easiest network topology for connecting computers or peripherals in a linear fashion.

• Requires less cable length than a star topology.

Disadvantages of bus topology :

• Difficult to identify the problems if the whole network goes down.

• It can be hard to troubleshoot individual device issues.

• Not great for large networks.

• Terminators are required for both ends of the main cable.

• Additional devices slow the network down.

• If a main cable is damaged, the network fails or splits into two.

Star :

            Alternatively referred to as a star network, star topology is one of the most common network setups. In this configuration, every node connects to a central network device, like a hub, switch, or computer. The central network device acts as a server and the peripheral devices act as clients.

Fig. Star Topology

Advantages of star topology :

• Centralized management of the network, through the use of the central computer, hub, or switch.

• Easy to add another computer to the network.

• If one computer on the network fails, the rest of the network continues to function normally.

Disadvantages of star topology :

• Can have a higher cost to implement, especially when using a switch or router as the central network device.

• The central network device determines the performance and number of nodes the network can handle.

• If the central computer, hub, or switch fails, the entire network goes down and all computers are disconnected from the network.

Ring :

                Alternatively referred to as a ring network, a ring topology is a computer network configuration where the devices are connected to each other in a circular shape. Each packet is sent around the ring until it reaches its final destination. Ring topologies are used in both local area network (LAN) and wide area network (WAN) setups. The picture to the right is a visual example of a network using the ring topology to connect several computers together.

Fig. Ring Topology

Advantages of ring topology

• All data flows in one direction, reducing the chance of packet collisions.

• A network server is not needed to control network connectivity between each workstation.

• Data can transfer between workstations at high speeds.

• Additional workstations can be added without impacting performance of the network.

Disadvantages of ring topology

• All data being transferred over the network must pass through each workstation on the network, which can make it slower than a star topology.

• The entire network will be impacted if one workstation shuts down.

• The hardware needed to connect each workstation to the network is more expensive than Ethernet cards and hubs/switches.

Mesh Topology :

                 A network setup where each computer and network device is interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down. It is a topology commonly used for wireless networks. Below is a visual example of a simple computer setup on a network using a mesh topology.

                              Fig. Mesh Topology

Advantages of a mesh topology :

• Can handle high amounts of traffic, because multiple devices can transmit data simultaneously.

• A failure of one device does not cause a break in the network or transmission of data.

• Adding additional devices does not disrupt data transmission between other devices.

Disadvantages of a mesh topology :

• The cost to implement is higher than other network topologies, making it a less desirable option.

• Building and maintaining the topology is difficult and time consuming.

• The chance of redundant connections is high, which adds to the high costs and potential for reduced efficiency.