WHAT IS NETWORKING?

Networking involves connecting computers and other

electronic devices for the purpose of sharing information and

resources and for communication.

Network CategoriesNetwork Categories

Local Area Network(LAN)

Metropolitan Area Network(MAN)

Wide Area Network(WAN)

What we can do by using networking?What we can do by using networking?

Share a single internet connection

What we can do by using networking?What we can do by using networking?

Share a printer, scanner and other hardware

What we can do by using networking?What we can do by using networking?

Share files and folders

What we can do by using networking?What we can do by using networking?

Play multi-computer games

CLIENTS, PEERS, AND SERVERS

Server • Computer that share resources across the network.•Responds from client by providing the requested information or denying the request.

Client • Computer that accesses shared resources.• Request information from server.

Peer • Computer that act as a server and at the same time can be client.

NETWORK MEDIUM

To communicate successfully, computers must share access to a common network medium.

Network medium:- Physical Cable (twisted –pair, coaxial, fiber optic) Wireless

To carry the signals one computer send to one or more other computers.

To access any network, computer must attach to network medium by using physical interface (NIC, network adapter)

NETWORK PROTOCOL When connected to a network, a computer must also be able to

use that connection.

They must share a common set of rules to communicate.

This rules must include how to interpret signals, how to identify “oneself” and other computers on a network, how to initiate and end networked communication.

NETWORK SOFTWARE

Computers need network software to issue the requests and responses that let them take the roles of clients and servers.

Computers that participate on a network run a network operating system (NOS) that determines what services that computer can offer or request.

NOS also controls access to the network service and network resources.

Example of NOS: - Windows Server 2003, Red Hat Linux, Windows NT.

NETWORK LAYOUT- TOPOLOGY

Network topology refers to physical layout of the computers, cables, resources and how those components communicate with each other.

BUS TOPOLOGY All components connect via a backbone. Signal are bounce. No longer a practical choice.

RING TOPOLOGY Connect directly to next computer in line, ending at the starting

computer. Signal travel in only one direction around the rings.

STAR TOPOLOGY Computers connected by cable segments to a central devices. Doesn't specify how signals should travel from computer to

computer

WIRELESS TOPOLOGY Eliminate the need for a visible physical topology. Two computers can communicate directly with one another in an

ad hoc topology (peer to peer technology) Wireless LAN – use a central device called an access point.

MESH TOPOLOGY Most fault tolerance but also the most expensive. Connecting each device in a network to every device in the

network.

A SIMPLE NETWORK LAYOUT DIAGRAM

OVERVIEW OF OSI LAYER NETWORK MODEL

What is layered model?Models help us to visualize different aspects of complex abstract systemsAlmost all communication can be broken down into independent layers that work interdependently.The ‘layers' (and protocols between them) conceptually represent negotiations between aspects of communication: Content, logical (encoding) and physical delivery of messages.

WHAT IS LAYERED MODEL?

WHAT IS A LAYERED MODEL?

OSI 7-Layer Model International Standards

Organization’s Open Systems Interconnection model

TCP/IP Model Developed by the Department

of Defense

2 models for network communications

THE OSI LAYERED MODELOSI – Open System InterconnectionLayered ApproachAllows better interoperability between

software and hardwareAllows design of elaborate but highly

reliable protocol stacks

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Physical LayerDefines all electrical and physical

specifications for devices.Major Functions

Establishment & Termination of Connections

Connection Resolution & Flow Control of Communication Resources

Modulation & Conversion between Digital Data

Example – radio, SCSI (Small Computer System Interface)

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Data Link LayerControls data transfer between network

entitiesPerforms error detection & correctionUses physical/flat Addressing SchemeExample - Ethernet

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Network LayerPerforms network routing, flow control,

segmentation, and error control functionsThe router operates at this layerUses local addressing scheme Example – IP, token ring

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Transport LayerProvide transparent transfer of data

between end users Controls reliability of a given link Some protocols are stateful and

connection oriented (cookies)Example – TCP / UDP

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Session LayerProvides mechanism for managing the

dialogue between end-user application processes

Provides for either duplex or half-duplex operation

Responsible for setting up and tearing down TCP/IP sessions

Example – NetBIOS

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Presentation LayerLittle to do with PowerPointControls syntactical differences in data

representation within end-user systemsMIME encoding is done at this layerExample - XML

OSI LAYERS - WHAT DOES EACH LAYER DO?

The Application LayerProvide semantic conversion between

associated application processes Interfaces directly to and performs

common application services for the application processes

Example – Telnet, Virtual Terminal

TCP/IP LAYERED NETWORK MODEL

Transmission Control Protocol and Internet Protocol

TCP/IP is a suite of protocols, also known as the Internet Protocol Suite

It was originally developed for the US Department of Defense Advanced Research Project Agency (DARPA) network, but it is now the basis for the Internet

Application

Transport

Internet

Network access

TCP/IP NETWORK MODEL LAYERS

TCP/IP LAYERS - WHAT DOES EACH LAYER DO?

As with the OSI model, the TCP/IP suite uses a layered model.

TCP/IP model has four or five - depending on who you talk to and which books you read!

Some people call it a four layer suite - Application, Transport, Internet and Network Access, others split the Network Access layer into its Physical and Datalink components.

Application

Transport

Internet

Network access

TCP/IP LAYERS - WHAT DOES EACH LAYER DO?

The combination of datalink and physical layers deals with pure hardware (wires, satellite links, network interface cards, etc.)

Access methods such as CSMA/CD (carrier sensed multiple access with collision detection)

Ethernet exists at the network access layer - its hardware operates at the physical layer and its medium access control method (CSMA/CD) operates at the datalink layer.

Application

Transport

Internet

Network access

This layer is responsible for the routing and delivery of data across networks.

It allows communication across networks of the same and different types and carries out translations to deal with dissimilar data addressing schemes. IP (Internet Protocol) and ARP (Address Resolution Protocol) are both to be found at the Internet layer.

Application

Transport

Internet

Network access

TCP/IP LAYERS - WHAT DOES EACH LAYER DO?

The transport layer is similar to the OSI transport model, but with elements of the OSI session layer functionality.

The two protocols found at the transport layer are: TCP (Transmission Control Protocol): reliable,

connection-oriented protocol that provides error checking and flow control through a virtual link that it establishes and finally terminates. Examples include FTP and Email

UDP (User Datagram Protocol): unreliable, connectionless protocol that not error check or offer any flow control. Examples include SNMP

Application

Transport

Internet

Network access

TCP/IP LAYERS - WHAT DOES EACH LAYER DO?

This layer is broadly equivalent to the application, presentation and session layers of the OSI model.

It gives an application access to the communication environment.

Examples: Telnet HTTP (Hyper Text Transfer Protocol) SMTP (Simple Mail Transfer Protocol)

Application

Transport

Internet

Network access

TCP/IP LAYERS - WHAT DOES EACH LAYER DO?