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ECE/IUPUIIntro to Computer Communication
Networks 1
Session 1. Introduction to Communication Networks
ECE/IUPUIIntro to Computer Communication
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, … )
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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.
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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)
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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,…
ECE/IUPUIIntro to Computer Communication
Networks 11
Direct ConnectionN hosts andN(N-1)/2 linesFault tolerantn Connectivity = N-1
Costs
ECE/IUPUIIntro to Computer Communication
Networks 12
Star NetworksEasyNeed a switchFaults in the switch is intolerablen Connectivity = 1
10/100BaseT
ECE/IUPUIIntro to Computer Communication
Networks 13
Ring Networks
EasySingle fault tolerablen Connectivity = 2
Token Ring, FDDI, ADM
ECE/IUPUIIntro to Computer Communication
Networks 14
Bus Networks
EasyScalabilityResource starvationRadio transmission, 10Base5, 10Base2Connectivity ?
ECE/IUPUIIntro to Computer Communication
Networks 15
Tree
ScalabilityBottle-neck at the top levelPOTSConnectivity ?
ECE/IUPUIIntro to Computer Communication
Networks 16
Daisy-chain
EasyArbitration and fairnessSCSI, UUNETScalable Ethernet hub (uplink)Connectivity ?
ECE/IUPUIIntro to Computer Communication
Networks 17
Network TopologyConsProsTopology
MaintainabilityFlexibilityIrregular
FairnessAffordableDaisy-chain
BottleneckScalabilityTree
Resource starvationAffordableBus
Fault sensitivityAffordableRing
Fault sensitivityAffordable Star
ScalabilityConnectivityDirect
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
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
ECE/IUPUIIntro to Computer Communication
Networks 21
Message Switching
Sender
Recipient
SW 1
SW 2
Time
ECE/IUPUIIntro to Computer Communication
Networks 22
Packet Switching
Sender
Recipient
SW 1
SW 2
Time
1 2 3 4
1 2 3
41 2 3
4
ECE/IUPUIIntro to Computer Communication
Networks 23
Circuit Switching
Sender
Recipient
SW 1
SW 2
Time
ConnectionEstablishment
Transfer
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