Unit-II 02 Introduction to Networking.ppt Part 1

Unit-II: Introduction to Networking Part - I

Lecture slide byVibhav Prasad MathurAssistant Professor (IT)College of Management and Economics Studies (CMES) 1

COLLEGE OF MANAGEMENT and ECONOMIC STUDIES (CMES)

Dehradun Campus

Introduction to Data Communications

and Networking

Vibhav Prasad MathurAssistant Professor (IT)College of Management and Economic Studies (CMES)Bidholi Campus, Dehradun

MBOI – 901: IT Applications In Petroleum Sector slides by Vibhav Prasad Mathur 2

References

• A. S. Tanenbaum, “Computer Networks”, 2e• Forouzen, "Data Communication And Networking“, TMH• W.T. Stallings, “Data And Computer Communication”• Comer, "Computer Network & Internet “• William A. Shay, "Understanding Data Communication & Networks”


Overview


Phases of Data Communication

• Five components of Data Communication




Direction of Data

• Simplex

• Duplex

• Full Duplex


Point-to-point connection


Multipoint Connection


Categories of Topology




Fully connected Mesh Topology for 5 devices


Star Topology


Bus Toplogy


Ring Topology




Categories Of Network

Network

Local Area Network (LAN)

Metropolitan Area Network

(MAN)Wide Area

Network (WAN)Wireless

Personal Area Network (WPAN)


LAN Introduction

• LANs are:– Privately owned. Can be up to several kilometers long;– Restricted so worst case transmission time can be contained. – Run at speeds of 10, 100, or more Mbps.– Low delay. High reliability.– Requires collision arbitration.

• Ethernet:– IEEE 802.3.– Bus based broadcast network with decentralized control at 10 or 100 Mbps.

• Token Ring:– IEEE 802.5– Ring based broadcast network with token arbitration at 4 or 16 Mbps


LAN


MAN Introduction

• MANs are:– Larger version of LAN ("city" wide).– Public or private / data or voice.– Broadcast - no switches.– Can be distinguished from LANs based on

wiring mechanism.




MAN


WAN Introduction

• WANs are: – Networks spanning large distances.

• Hosts or End Systems -– Machines running user applications.

• (Communication) Subnet –– Connections between hosts - transmission lines + switches.– A "locality" understanding each other's addresses.

• Circuits/Channels/Trunks -– Transmission lines move the bits.

• Packet switching nodes/Intermediate systems/Data switching exchanges – Specialized computers moving data between several inputs to several outputs.

• Router - Generic term for switching computers.• Point-to-point/Store-and-forward/Packet-switched –

– Moving through a series of routers, packets are received at a router, stored there, then forwarded to the next router.


WAN


Wireless Network categories

• Wireless networks are many and diverse but are frequentlycategorized into three groups based on their coverage range:

1. Wireless Wide Area Networks (WWAN),2. WLANs, and3. Wireless Personal Area Networks (WPAN)*.

1. WWAN includes wide coverage area technologies such as 2G cellular,Cellular Digital Packet Data (CDPD), Global System for MobileCommunications (GSM), and Mobitex.

2. WLAN, representing wireless local area networks, includes 802.11,HiperLAN, and several others.

3. WPAN, represents wireless personal area network technologies such asBluetooth and IR.

• All of these technologies are “tetherless”—they receive and transmit informationusing electromagnetic (EM) waves.

• Wireless technologies use wavelengths ranging from the radio frequency (RF: range ofabout 3 Hz and 30 GHz) band up to and above the IR band.




WPAN Introduction

• WPAN is a wireless network designed for handheld andportable devices such as PDAs, cell phones, andTablet/Laptop computers, and is intended for use by onlyone or two persons.

• Maximum distance 10 mt. Or 33 feet.• Usually work on Bluetooth technology


Bluetooth• Universal radio interface for ad- hoc wireless connectivity; Interconnecting computer

and peripherals, handheld devices, PDAs, cell phones – replacement of IrDA.Emulates an RS-232 control and data signals over Bluetooth Baseband.

• Current specification : Bluetooth 1.2• Bluetooth technology

– Short-range (theoretically 10 – 100m), Wireless (ISM frequency band –2.4GHz), Point-to-point or point-to-multipoint, Voice and data transfer (up to1Mb/s)

• Key features: Robustness, Low complexity of use, Low power, Low cost• Bluetooth enabled devices: Laptops, Cellular phones, Personal Digital Assistants,

Headsets, Printers, Keyboards/mice, GPS, etc… Up to 7 slaves can be connectedto 1 master

• Service Discovery Protocol (SDP): Provides a means for a Bluetooth device todiscover what services of another device are available and determine thecharacteristics of those available services, including Caching of discovered services

• Topology: Overlapping piconets (stars) forming a scatternet (Linking ofmultiple co-located piconets through the sharing of common master or slavedevices)

Harald Bluetooth; 10th century Danish King, managed to unite Denmark and Norway


Piconet (Physical Channel shared among several devices)

• Collection of devices connected in an ad-hocfashion

• One unit acts as master and the others asslaves for the lifetime of the piconet

• Master determines hopping pattern, slaveshave to synchronize

• Each piconet has a unique hopping pattern• Participation in a piconet = synchronization to

hopping sequence• Each piconet has one master and up to 7

simultaneous slaves (> 200 could be parked)


Wireless LAN benefits

• WLANs offer four primary benefits:– User Mobility — Users can access files, network resources, and the Internet

without having to physically connect to the network with wires. Users can bemobile yet retain high-speed, real-time access to the enterprise LAN.

– Rapid Installation — The time required for installation is reduced becausenetwork connections can be made without moving or adding wires, or pullingthem through walls or ceilings, or making modifications to the infrastructure cableplant. For example, WLANs are often cited as making LAN installations possiblein buildings that are subject to historic preservation rules.

– Flexibility — Enterprises can also enjoy the flexibility of installing and takingdown WLANs in locations as necessary. Users can quickly install a small WLANfor temporary needs such as a conference, trade show, or standards meeting.

– Scalability — WLAN network topologies can easily be configured to meetspecific application and installation needs and to scale from small peer-to-peernetworks to very large enterprise networks that enable roaming over a broadarea.




RF and IR Wavelength Spectrum

• RF

• IR • The C-band is the dominantband for long-distancetelecommunication networks.

• The S and L bands are basedon less well establishedtechnology, and are not aswidely deployed.


Why Wireless?

• (+) No wires. Convenience, flexible. But…– (-) Relatively slow speeds, typically 5 Mbps with

802.11b. Nowhere near the 100 Mbps of typicalwired connection.

– (-) Wireless access points are hubs, not switches.Bandwidth is shared among wireless users. Think ofit as phone party lines.

– (-) Data is freely available “in the air”.• Traffic is easily sniffed.• Data is not encrypted unless the protocol is encrypted (e.g.,

SSL etc.).


Wireless Terms• Access Point (or AP): device that sends and receives wireless signals.

Usually directly connected to the wired net.– The hub of a wireless network. Wireless clients connect to the access point, and traffic

between two clients must travel through the access point. Access points are also referred toas "wireless routers," "wireless gateways," and "base stations." The true access points don'talso share Internet connections or bridge between wired and wireless networks.

• SSID: the network name that Access Points broadcast.– Departments and home users may want to use other names.– Users can roam between access points with the same SSID.

• Channel: radio frequency used by AP’s.– AP’s near one another should use different channels to minimize noise.– A specific portion of the radio spectrum; for example, the channels allotted to one of the

wireless networking protocols.– 802.11b and 802.11g use 14 channels in the 2.4 GHz band, only 3 of which don't overlap (1,

6, and 11). In the 5 GHz band,– 802.11a uses 8 channels for indoor use and 4 others for outdoor use, and none of them

overlap.

• Hot spot: A place where you can connect to a public wireless network.


Difference between Wired and Wireless




‘Wifi’ – What it stands for?“Wi-fi / Wireless-Fidelity, Otherwise known as 802.11 WirelessNetwork, is an open-standard, open spectrum, open-source, open-hardware, mode of wireless inter-connectivity for participatingdevices.”


Components of Wireless Network

Base stations, Access points, or Gateways

Wireless Network cards• Radios which send and receive signals from other radios

or access points, usually PCMCIA* cards which fit intoLaptop expansion slots, or PCI Bus in case of Desktopcomputers. (There are other, simpler options using USB).PDAs like PALM, and Pocket PC having a compact flash slotcan also connect.

* PCMCIA – Personal Computer Memory Card International Association.

• The base station sends and receives radio signals to andfrom the Wi-Fi radio in your laptop or PC, enabling you toshare your Internet connection with other users on the network.Access points and gateways have a wide range offeatures and performance capabilities, but they all provide thisbasic network connection service.


Satellite Communication

• Satellites Access Schemes– Frequency Division Multiple

access– Time Division Multiple access

• Satellite Organizations– IntelSat– Inmarsat– Intersputik– Regional Satellite Systems– Separate international satellite

systems METERBURST COMMUNICATIONRelies on the phenomenon of reflecting radio

waves off the ionized trails left by micro meters as they enter the atmosphere and disintegrate.


VSAT

• Very Small Aperture Transmission• Requires Small 1 – 2 Meter Dish

Antenna• Uses DAMA (Demand Assigned

Multiple Access ) System for Fullmesh point to point or point tomultipoint connectivity




Mobile Technology


32 Watt Solar Panel

GPRS Enabled Cell Phone(HUTCH or Airtel @ Rs. 499/- pm)

GPRS / CDMACellular Phone based service

Cell tower

(Bluetooth Enabled)

• Covers 30% of India’s LandMass• Using GSM/CDMA cellular providers

• Reliable, Always-On Internet Connection for a fixed package

Rural Internet Kiosk(Bluetooth Enabled)Rural Internet Kiosk(Bluetooth Enabled)


1G /Analog

• First generation of mobile technology using non-standardizedanalog radio systems which carried only voice traffic

• Less secure and prone to interference when signal is weak• AMPS (Advanced Mobile Phone System)

– Original standard for analog cellular phone service– Used primarily in North America, Latin America, Australia, and parts of Russia

and Asia

• ETACS (Extended Total Access Communication System)– Developed in the UK and available in Europe and Asia

• TACS (Total Access Communication System)– Used in Britain for the 900 MHz frequency band– Based on the US AMPS system and later adopted in other countries including

Hong Kong and Japan


2G• 2nd generation of mobile telephony systems using digital radio technology

and supporting high bit rate voice, limited data communications andimproved quality

• GSM (Global System for Mobile communications)– Uses 900 MHz and 1800 MHz in Europe and 1900 MHz in America– Widely adopted in Europe and Asia and weakly supported in North America

• CDMA One (Code Division Multiple Access)– Uses a spread spectrum technique to scatter a radio signal across a wide range

of frequencies– Widely deployed in the United States, South America and parts of Asia

• TDMA (Time Division Multiple Access)– Divides each cellular channel into time slots in order to increase the amount of

data that can be carried– Operated in the Americas, New Zealand, parts of Russia and Asia




2.5 G

• 2.5G is a bridge from the voice-centric 2G networks to the data-centric

• 3G networks and incorporates higher speeds to support datatransport

• GPRS (General Packet Radio Service)– An upgrade to GSM and TDMA networks which introduces packet data

transmission and to be deployed in all regions

• EDGE (Enhanced Data for GSM Evolution)– Technology upgrade for GSM and TDMA networks beyond GPRS to allow

greater data rate per time slot Deployed mainly in the United States and Europe

• CDMA 2000 1x (Code Division Multiple Access 1X)– Technology upgrade for CDMA one networks


3G• 3G offers enhancements to current applications including greater

data speeds, increased capacity for voice and data and a broaderrange of services

• CDMA2000 1xEV-DO (CDMA 1x Evolutionary-Data Only)– Evolution of the CDMA2000 air-interface standard for greater spectral efficiency

and optimized for data traffic alone

• CDMA2000 1xEV-DV (CDMA 1x Evolutionary-Data and Voice)– Evolution of the CDMA2000 air-interface standard for greater spectral efficiency

and optimized for data and voice traffic

• WCDMA (Wide Code Division Multiple Access )– Evolution path by the GSM world and optimized to support high-speed mobile

multimedia

• TD -SCDMA (Time Division -Synchronous CDMA)-– Developed by the Chinese Academy of Telecommunications Technology (CATT)

and Siemens, combines TDMA with a synchronous CDMA component and verywell suited for data and voice transmission


2G & 3G — CDMACode Division Multiple Access

• Spread spectrum modulation– Originally developed for the military– Resists jamming and many kinds of interference– Coded modulation hidden from those w/o the code

• All users share same (large) block of spectrum– One for one frequency reuse– Soft handoffs possible

• Almost all accepted 3G radio standards are based onCDMA– CDMA2000, W-CDMA and TD-SCDMA


Multi-Access Radio Techniques

Courtesy of Petri Possi, UMTS World




Multiplexing (1)• The cost of a wire is pretty much constant, independent of the bandwidth of

that wire - costs come from installation and maintenance of the physicalspace (digging, etc.), not from the media or the electrical support structure.So, how can we stuff more through that medium?

• The answer is MultiplexingFrequency Division Multiplexing:The frequency spectrum is divided upamong the logical channels - eachuser hangs on to a particularfrequency. The radio spectrum (and aradio) are examples of the media andthe mechanism for extractinginformation from the medium. Notethat this is analog stuff.


Multiplexing (2)• Wavelength Division Multiplexing: The same as FDM, but applied to fibers.

There's great potential for fibers since the bandwidth is so huge (25,000 GHz).• Time Division Multiplexing: In TDM, the users take turns, each one having

exclusive use of the medium in a round robin fashion. TDM can be all digital.


Networking Software


Networking Software

• Major issues to be addressed:1. Number of logical channels per connection (for priority purposes)2. Error control. (garbled or missing.)3. Preservation of message ordering.4. Flow control.5. Breaking up messages into a smaller chunks (and reassembly.)6. Multiplexing messages on same connection.7. Routing - how to get from one host to another.




Network Software Terms (1)

• Layers– The concept that network software is organized functionally into levels. A level

on one host talks to the same level on another host (its peer).– Purpose of each layer is to provide services to the layer above it.

• Protocol– The protocol is the convention or standard that a layer uses to talk to the other

layer. An agreement or standard on the conversation.

• Physical Medium– Underneath the layers is the wire or fiber or whatever.

• Interface– Defines the services that one layer offers another (either up or down.) – Important to keep this simple and clean.– Important that each layer perform specific actions.


Network Software Terms (2)

• Network architecture– A set of layers and protocols. It contains details on what happens in the layer and

what the layers says to its peer.– Functional interfaces and implementation details are not part of the spec, since

that's not visible outside the machine.

• Protocol stack– A list of protocols used by a system, one protocol per layer.

• Information flow– "Send_to_peer" rather than "call_next_layer_down".


Network Software Services Types• Connection oriented service

– Like the phone system. The system establishes a connection, uses it,and closes it.

– Acts like a tube. Data comes out the other end in the same order as itgoes in.

– Connection Setup– Data Transfer– Connection Termination

• Connectionless service– Like the post office. Each message has the entire address on it. Each

message may follow a different route to its destination. Ordering notmaintained.

– Data Transfer


Network Software Services Summary

• Quality of service– Will the message arrive?? A reliable connection-oriented service guarantees

success.– Message sequence - message boundaries and order are maintained.– Byte streams - messages are broken up or combined; flow is bytes.




The Relationship Of Services To Protocols

• Services are primitives that a layer provides for the layer above it.• Protocols are rules governing the meaning of

frames/packets/messages exchanged with the peer entity.


Message/Data Transmission Techniques(Switching Techniques)

• Circuit switching there is a dedicated communication path between two end stations• Packet switching

– Packet: Block of bytes that divides into users data field and a reserved areacalled header

– Data is transmitted in packets– Each packet contains portion of data plus control information– Control information includes route and intended destination– Packets are handled by

• Datagram approach• Virtual circuit approach

• Message switching– Complete message is transmitted from node to node

• Frame relay– Service to transfer bits at a reasonable speed and low cost– Reduce network slowness– Efficient bandwidth utilization– Decreases communication equipment cost


Packet Switching

• Packet Switching Reduces Trunk Line Costs– Packets from several conversations are multiplexed

on trunk lines– Conversations do not need the full capacity of the

shared trunk lines. This reduces trunk line costs.

Trunk LinkPacket from A to B Packet from C to D


Packet Switching

Trailer HeaderData Field

AddressField

Message Structure

Packet

OtherHeaderField




Switching Decision

StationA

StationB

StationC

StationD

Switch

Station ATransmitsto Station C

Switch SendsSignal out aSingle Port

Switch receivesa frame, sendsit back out1 2 3 4 5 6


Packet Switching

Original Message

Computer X

PacketSwitchA

Packet

SwitchingDecision

B

C

Computer Y

FED

1. Break message intoSmaller packets(also known as frames)

2. Route packets individually;Packet switches along the wayMake decisions about the packet


Reference Model

• There are two competing models for howthe software is layered. These are the:– OSI model and– TCP models.

• To be covered in next session……


Questions and Suggestions

Unit-II 02 Introduction to Networking.ppt Part 1

Documents

Transcript of Unit-II 02 Introduction to Networking.ppt Part 1