Networking

Networking Concepts

What is Network

• When two or more computers are connected with each other in such a way so that they can exchange information, is called networks and this concept is called networking.

Types Of Network

• LAN or Local Area Network is a computer network (or data communications network) which is confined in a limited geographical area such as building or college campus.

• WAN or Wide Area Network spans a large geographic area, such as a state, province or country.

• MAN or Metropolitan Area Network interconnects users with computer resources in a geographic area or region larger than that covered by even a large LAN but smaller than the area covered by a WAN

Network Topologies

• Bus Topology

Bus Topology

• Advantage– Easy to install.– Deployment costs are usually low.– Easy to add systems to network.– Require less cable length than other

topologies.

• Disadvantage– Out-of-date technology.– If cable breaks, whole network is down.– Can be difficult to troubleshoot.– Unmanageable in a large network.

Ring Topology

Ring Topology

• Advantage– All station on network equal access.– It has single point of contact.

• Disadvantage– High cost of implementation– If any of the computers fails in the ring the

network collapses.

Star Topology

Star Topology

• Advantages– Easy to install.– Easier to troubleshoot – Easy to add systems to network.– Widely used– Centralized management

• Disadvantages– Costs are usually higher than with bus or

ring networks.– If you have only one central device and it

fails, it brings the network down.

Tree Topology

Tree Topology

• Advantages– A point to point connection is possible with Tree

Networks. – All the computers have access to the larger and

their immediate networks.

• Disadvantages– Since the Tree Topology network is big it is

difficult to configure and can get complicated after a certain point.

– If the backbone line breaks, the entire segment goes down

– Difficult to configure

Mesh Topology

• Complete and Partial Mesh Topology

Mesh Topology

• Advantages– It is possible to transmit data from one node to

many nodes at the same time.

• Disadvantages – Redundancy due to number of network

connection– Complex structure– Difficult to identify the problem if network shut

down

Hybrid Topology

Transmission Modes

Transmission modes

SimplexHalf

DuplexFull

Duplex

TCP / IP Protocol

It is a 5 layer protocol. The layers are:

• Application layer

• Transport layer

• Network layer

• Data link layer

• Physical layer

• Network Interface(Data Link + Physical Layer) - Specifies details of how data is physically sent through the network, including how bits are electrically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted-pair copper wire.

• Network Layer - Packages data into IP packets, which contain source and destination address information that is used to forward the packets between hosts and across networks. Performs routing of IP packets.

• Transport Layer - Provides communication session management between host computers.

• Application Layer - Defines TCP/IP application protocols and how host programs interface with transport layer services to use the network like FTP, SMTP.

Connectivity Devices

• Repeater

Network repeaters regenerate incoming electrical, wireless or optical signals.

• Hub• Can be defined as multi port repeater.

• Bridge

A network bridge connects network segments. It can divide the large segment into smaller ones.

• Switch

It is used to transfer the packet from source to appropriate output port.

• Router

It Connects two or more logical separate networks.

INTERNET

Introduction

• 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.

• A global network connecting millions of computers. More than 100 countries are linked into exchanges of data, news and opinions.

• Internet makes use of the internet protocol and the transmission Control protocol.

Introduction

• There are various ways and means to access the internet. With the advancement in technology people can now access internet services through their cell phones, play stations and various gadgets.

• With the development and the wide spread application of internet electronic mail people from all across the globe come together and communication has become much easier than ever before.

Internet Application

• Communication• Information• Entertainment• Services• E-Commerce

Services Provided by the Internet

• E-mailElectronic Mail is a method of sending a message from a user at a computer to a recipient on another computer.

• Video Conferencing• FTP (File Transfer Protocol)

This facility is a method of gaining limited access to another machine in the Internet, and obtaining files from it. You need full Internet connectivity, to do ftp interactively.

• TelnetTelnet is the Internet facility that allows you to execute commands on a remote host (another computer, most likely one to which you do not have physical access) as if you were logged in locally.

• WWWThe official description describes the World-Wide Web as a "wide-area *hypermedia* information retrieval initiative aiming to give universal access to a large universe of documents".

• Usenet and Mailing listIf you want to receive periodically information about certain topics, there are two things you can do. The first possibility is to read the news groups of the Internet.

If you do not have full Internet connectivity, you can subscribe to a mailing list. What you have to do is to send your name to some server, and every day you will receive an e-mail containing news concerning the topic you have subscribed to.

Commonly Protocol used by Internet

• POP3– In computing, the Post Office Protocol (POP)

is an application-layer Internet standard protocol used by local e-mail clients to retrieve e-mail from a remote server over a TCP/IP connection. POP and IMAP (Internet Message Access Protocol) are the two most prevalent Internet standard protocols for e-mail retrieval.

• Hypertext Transfer Protocol (HTTP) an application-level protocol for distributed, collaborative, hypermedia information systems.

• SMTP– Simple Mail Transfer Protocol (SMTP) is an

Internet standard for electronic mail (e-mail) transmission across Internet Protocol (IP) networks. SMTP is specified for outgoing mail transport.

• UDP• With UDP, computer applications can send

messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network without requiring prior communications to set up special transmission channels or data paths.

WWW – World Wide Web

• The World Wide Web is a system of interlinked hypertext documents contained on the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them using hyperlinks.

• There are several applications called Web browsers that make it easy to access the World Wide Web; Few most popular being:

o Mozilla Firefoxo Operao Netscape Navigatoro Microsoft's Internet Explorer.