session 1. introduction to communication...

ECE/IUPUIIntro to Computer Communication

Networks 1

Session 1. Introduction to Communication Networks


Networks 2

Network Services

The Traditional Networksn Postal mailn Water supply networksn Electricity power networksn Transportation networksn Cable and television broadcast networksn Telephone

Communication networks – microwave, electronic and opticaln Wireless communication (cellular, satellite, … )n Public networks (telephone, Internet, … )n Private networks (bank, military, airlines, … )


Networks 3

Radio and Television Broadcasting

Multiple recipientsPassiven All user receives identical contentsn No user sends a message

High quality requiredTolerable delayn Several secondsn Not tolerable a variation of delay, though


Networks 4

Telephone service-1

Real-time servicen A few hundred mili-seconds delay

Peer-to-peer communicationReliablen No automatic re-transmission

Connection-orientedn First,established a connection


Networks 5

Telephone Service-2

Caller

TelecomNetworks

Central OfficeCallee

Central Office

Access Networks Access Networks

Connection established forbidirectional conversation

pickup

dial tone

dial the numberroute

ringring

ring

callee pick up the phone

hang-up

terminating signals


Networks 6

Cellular Telephone Service

Mobilityn Shared mediumw Radio Transmission

n Hand-offw Able to keep conversation when moving an area to

another

n Roamingw Able to carry a hand-set out of home base

Radio transmissionn Low quality, low availability, and a security hole.


Networks 7

Electronic mail

Not a real-time at alln Tolerable to large delays: possibly several days

Forward a whole message at a timeNo need of connection-oriented


Networks 8

World Wide Web

Client-server modelRemote document retrievaln Text filen Binary file - audio, image and application filen Link – specified with URL

Interactive but not a real-timeHyperText Transfer Protocol (HTTP)


Networks 9

Video-on-demand (VOD)

Integration of video rental store and video playerInteractiven STOP, PLAY, FF, REW, PAUSE

No need of real-timeBillingCopyright protect


Networks 10

What is a protocol?A set of rules governing how two parties are to interact.

Postal Mail Protocoln Sender’s address at the left -upper cornern Recipient ’s address at the centern Stamps at the right -upper corner

Walkie-Talkie Protocoln Listenn Hear “Over!” or nothing

w Say a sentence and “Over!”while holding down the buttonw Release the button

Protocols in communication networksn HTTP, FTP, TCP, IP, Ethernet, CDMA, ATM, SONET, PPP, ICMP,

SNMP, SMTP, ARP, RARP, DHCP, RTP, UDP, HDLC, IGMP, RIP, OSFP, LCP, NHRP, RSVP,…


Networks 11

Direct ConnectionN hosts andN(N-1)/2 linesFault tolerantn Connectivity = N-1

Costs


Networks 12

Star NetworksEasyNeed a switchFaults in the switch is intolerablen Connectivity = 1

10/100BaseT


Networks 13

Ring Networks

EasySingle fault tolerablen Connectivity = 2

Token Ring, FDDI, ADM


Networks 14

Bus Networks

EasyScalabilityResource starvationRadio transmission, 10Base5, 10Base2Connectivity ?


Networks 15

Tree

ScalabilityBottle-neck at the top levelPOTSConnectivity ?


Networks 16

Daisy-chain

EasyArbitration and fairnessSCSI, UUNETScalable Ethernet hub (uplink)Connectivity ?


Networks 17

Network TopologyConsProsTopology

MaintainabilityFlexibilityIrregular

FairnessAffordableDaisy-chain

BottleneckScalabilityTree

Resource starvationAffordableBus

Fault sensitivityAffordableRing

Fault sensitivityAffordable Star

ScalabilityConnectivityDirect


Networks 18

Hierarchical Network, 1

Communication networks grow so fast that a organization cannot control them alone.Need based topologyNeed based techniquesn Protocols and Standards

Cost optimized


Networks 19

Hierarchical Network, 2

BackboneNetwork

ConcentratorBackboneNetwork

Concentrator

Switch Offiicein Hamilton County

Switch OfficeMarion County

Multiplexer M

ultip

lexe

r

Switch Officein Indianapolis

To ClevelandTo Chicago


Networks 20

Switching Methods

Message switchingn Whole message passed to the next hopn Storagen Postal mail, telegraph

Packet switchingn Packet size – fixed, variablen Routing for each packetn Internet, ATM

Circuit switchingn Resource is dedicated to a single conversationn Connection established before communicationn Telephone


Networks 21

Message Switching

Sender

Recipient

SW 1

SW 2

Time


Networks 22

Packet Switching

Sender

Recipient

SW 1

SW 2

Time

1 2 3 4

1 2 3

41 2 3

4


Networks 23

Circuit Switching

Sender

Recipient

SW 1

SW 2

Time

ConnectionEstablishment

Transfer

session 1. introduction to communication...

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