COSC4377 Fall 2013 - UHjohnsson/COSC4377_2013/Lecture01.pdf · They’re in PowerPoint form so you...

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Lennart Johnsson

2013‐08‐27COSC4377 Lennart Johnsson

2013‐08‐27COSC4377

COSC4377Fall 2013

Lecture 1

Lennart Johnsson

2013‐08‐27COSC4377

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Chapter 1Introduction

Computer Networking: A Top Down Approach 6th edition Jim Kurose, Keith RossAddison-WesleyMarch 2012

A note on the use of these ppt slides:We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you see the animations; and can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: If you use these slides (e.g., in a class) that you mention their source

(after all, we’d like people to use our book!) If you post any slides on a www site, that you note that they are adapted

from (or perhaps identical to) our slides, and note our copyright of this material.

Thanks and enjoy! JFK/KWR

All material copyright 1996-2012J.F Kurose and K.W. Ross, All Rights Reserved

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Chapter 1: introductionour goal:• get “feel” and

terminology

• more depth, detail laterin course

• approach:– use Internet as example

overview:• what’s the Internet?

• what’s a protocol?

• network edge; hosts, access net, physical media

• network core: packet/circuit switching, Internet structure

• performance: loss, delay, throughput

• security

• protocol layers, service models

• history

3Slide from Kurose & Ross, 6th Ed

Lennart Johnsson

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Chapter 1: roadmap

1.1 what is the Internet?

1.2 network edge

end systems, access networks, links

1.3 network core

packet switching, circuit switching, network structure

1.4 delay, loss, throughput in networks

1.5 protocol layers, service models

1.6 networks under attack: security

1.7 history


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0

10

20

30

40

50

60

70

80

90

100

0

500

1,000

1,500

2,000

2,500

3,000

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012* 2013*

Per 100 inhabitants

millions

Individuals using the Internet (in millions)

Individuals using the Internet per 100 inhabitants

Global numbers of individuals using the Internet, total and per 100 inhabitants, 2001‐2013

Note: * EstimateSource: ITU World Telecommunication /ICT Indicators database

http://www.itu.int/en/ITU‐D/Statistics/Pages/stat/default.aspx

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76.8

38.8

30.7

0

10

20

30

40

50

60

70

80

90

100

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012* 2013*

Per 100 inhabitants

Individuals using the Internet per 100 inhabitants, 2001‐2013

Developed

World

Developing

The developed/developing country classifications are based on the UN M49, see: http://www.itu.int/ITU‐D/ict/definitions/regions/index.htmlNote: * EstimateSource: ITU World Telecommunication /ICT Indicators database


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Internet bandwidth per user

http://www.itu.int/ITU‐D/ict/facts/2011/material/ICTFactsFigures2011.pdf

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Fixed Broadband Data Rates

http://www.itu.int/en/ITU‐D/Statistics/Documents/facts/ICTFactsFigures2013.pdf

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Internet Statistics• The percentage of individuals using the Internet continues to grow

worldwide and by end 2011 2.3 billion people were online.

• In developing countries, the number of Internet users doubled between 2007 and2011, but only a quarter of inhabitants in the developing world were online by end 2011.

• The percentage of individuals using the Internet in the developed world reached the 70%landmark by end 2011. In Iceland, the Netherlands, Norway and Sweden more than 90%of the population are online.

• By end 2011, 70% of the total households in developed countries had Internet, whereasonly 20% of households in developing countries had Internet access. Some outstandingexceptions include Lebanon and Malaysia with 62% and 61% of households with Internetrespectively.

• Total international Internet bandwidth increased seven‐fold over the last five yearsreaching 76’000 Gbit/s by end 2011. This equates to 34’000 bit/s per Internet user worldwide.

• Major differences in Internet bandwidth per Internet user persist between regions:on average, a user in Europe enjoys 25 times as much international Internet capacityas a user in Africa.

http://www.itu.int/ITU‐D/ict/statistics/material/pdf/2011%20Statistical%20highlights_June_2012.pdf

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What’s the Internet: “nuts and bolts” view

Tens of millions of connected (computing) devices: hosts = end systems running network apps

Communication links: fiber, copper, radio,

satellite transmission rate:

bandwidthlatency

Packet “switches”:forward packets (chunks of data) routers and switches

wiredlinks

wirelesslinks

router

mobile network

global ISP

regional ISP

home network

institutionalnetwork

smartphone

PC

server

wirelesslaptop

10Slide derived from Kurose & Ross, 6th Ed

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End Systems ‐ “Fun” internet appliances

IP picture framehttp://www.ceiva.com/

Web-enabled toaster +weather forecaster

Internet phonesInternet refrigerator

Slingbox: watch,control cable TV remotely

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Tweet-a-watt: monitor energy use

Slide from Kurose & Ross, 6th Ed

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End Systems ‐ Internet Data Centers

Facebook Lulea

Facebook

Google

Google Dalles, OR Google

Google

Google

Some with 100+k servers

Undersea telecom cables

Satellite dish (Google)

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• Internet: “network of networks”– Interconnected ISPs

• Protocols control sending, receiving of msgs– e.g., TCP, IP, HTTP, Skype, 802.11

• Internet standards– RFC: Request for comments

– IETF: Internet Engineering Task Force

What’s the Internet: “nuts and bolts” viewmobile network

global ISP

regional ISP

home network

Institutional network


TCP: Transmission Control ProtocolIP: Internet ProtocolHTTP: Hypertext Transfer ProtocolISP: Internet Service ProviderRFC: Request for CommentsIETF: Internet Engineering Task Force

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What’s the Internet: a service view

• Infrastructure that provides services to applications:– Web, VoIP, email, games, e‐commerce, social nets, …

• provides programming interface to apps– hooks that allow sending and receiving app programs to “connect” to Internet

– provides service options, analogous to postal service

mobile network

global ISP

regional ISP

home network



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What’s a protocol?

human protocols:• “what’s the time?”

• “I have a question”

• introductions

… specific msgs sent

… specific actions taken when msgs received, or other events

network protocols:• machines rather than

humans

• all communication activity in Internet governed by protocols

protocols define format, orderof msgs sent and receivedamong network entities,

and actions taken on msg transmission, receipt


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a human protocol and a computer network protocol:

Q: other human protocols?

Hi

Hi

Got thetime?

2:00

TCP connectionresponse

Get http://www.awl.com/kurose-ross

<file>time

TCP connectionrequest

What’s a protocol?


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Chapter 1: roadmap

1.1 what is the Internet?

1.2 network edge

end systems, access networks, links

1.3 network core

packet switching, circuit switching, network structure

1.4 delay, loss, throughput in networks

1.5 protocol layers, service models

1.6 networks under attack: security

1.7 history


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A closer look at network structure:

access networks, physical media:‐ wired, wireless communication links

network core: ‐ interconnected routers‐ network of networks

mobile network

global ISP

regional ISP

home network



network edge:‐ hosts: clients and servers‐ servers often in data centers

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Access networks and physical media

Q: How to connect end systems to edge router?

• residential access nets

• institutional access networks (school, company)

• mobile access networks

keep in mind: • bandwidth (bits per second)

of access network?

• shared or dedicated?


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Access net: Digital Subscriber Line (DSL)

central office

ISP

telephonenetwork

DSLAM

voice, data transmittedat different frequencies over

dedicated line to central office

use existing telephone line to central office DSLAM (DSL Access Multiplexer)

data over DSL phone line goes to Internet voice over DSL phone line goes to telephone net

< 2.5 Mbps upstream transmission rate (typically < 1 Mbps) < 24 Mbps downstream transmission rate (typically < 10 Mbps)

DSLmodem

splitter

DSL access multiplexer


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Access net: cable network

cablemodem

splitter

…

cable headend

Channels

VIDEO

VIDEO

VIDEO

VIDEO

VIDEO

VIDEO

DATA

DATA

CONTROL

1 2 3 4 5 6 7 8 9

frequency division multiplexing: different channels transmittedin different frequency bands


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data, TV transmitted at different frequencies over shared cable

distribution network

cablemodem

splitter

…

cable headend

CMTS

ISP

cable modemtermination system

HFC: Hybrid Fiber Coax asymmetric: up to 30Mbps downstream transmission rate, 2 Mbps

upstream transmission rate

Network of cable, fiber attaches homes to ISP router homes share access network to cable headend unlike DSL, which has dedicated access to central office

Access net: cable network


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Access net: home network

to/from headend or central office

cable or DSL modem

router, firewall, NAT (Network Address Translation)

wired Ethernet (10, 100, 1,000 Mbps)

wireless access point (11, 54, 150-600 Mbps)

wirelessdevices

often combined in single box


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Enterprise access networks (Ethernet)

typically used in companies, universities, etc

10 Mbps, 100Mbps, 1Gbps, 10Gbps transmission rates

today, end systems typically connect into Ethernet switch

Ethernet switch

institutional mail,web servers

institutional router

institutional link to ISP (Internet)


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Wireless access networks

• shared wireless access network connects end system to router

– via base station aka “access point”

wireless LANs: within building (100 ft) 802.11b/g (WiFi): 11, 54 Mbps

transmission rate

wide-area wireless access provided by telecommunications

(telco) (cellular) operator, 10’s km between 1 and 100+ Mbps 2G, 3G, 4G: LTE

(Long Term Evolution)

to Internet

to Internet


LAN: Local Area Network

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Host: sends packets of data

host sending function:

• takes application message

• breaks into smaller chunks, known as packets, of length Lbits

• transmits packet into access network at transmission rate R

– link transmission rate, aka link capacity, aka link bandwidth

R: link transmission ratehost

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two packets, L bits each

packettransmission

delay

time needed totransmit L-bit

packet into link

L (bits)R (bits/sec)= =


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Physical media

• bit: propagates betweentransmitter/receiver pairs

• physical link: what lies between transmitter & receiver

• guided media: – signals propagate in solid media:

copper, fiber, coax

• unguided media:– signals propagate freely, e.g.,

radio

twisted pair (TP)

• two insulated copper wires– Category 5: 100 Mbps, 1 Gbps

Ethernet

– Category 6: 10 Gbps


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Physical media: coax, fiber

coaxial cable:• two concentric copper

conductors

• bidirectional

• broadband:– multiple channels on cable

– HFC

fiber optic cable: glass fiber carrying light pulses,

each pulse a bit

high‐speed operation: high‐speed point‐to‐point

transmission (e.g., 10’s‐100’s Gpbs transmission rate)

low error rate: repeaters spaced far apart

immune to electromagnetic noise


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Physical media: radio

• signal carried in electromagnetic spectrum

• no physical “wire”

• bidirectional

• propagation environment effects:– reflection

– obstruction by objects

– interference

radio link types: terrestrial microwave

e.g. up to 45 Mbps channels LAN (e.g., WiFi)

802.11b (1999) 11 Mbps, 802.11g (2002) 54 Mbps 802.11n (2007) 600 Mbps 802.11ac (2012) <3600 Mbps

wide-area (e.g., cellular) 3G cellular: ~ few Mbps 4G cellular: up to 299.6 Mbps

download, 75.4 Mbps upload satellite

Kbps to 45Mbps channel (or multiple narrower channels)

270 msec end-end delay geosynchronous versus low altitude


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Mobile Cellular Subscriptions

2013*

Total 6.8 billion

Developing

Developed

128.2

96.289.4

0

20

40

60

80

100

120

140

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012* 2013*

Per 100 inhabitants

Mobile‐cellular subscriptions per 100 inhabitants, 2001‐2013

DevelopedWorld

The developed/developing country classifications are based on the UN M49, see: http://www.itu.int/ITU‐D/ict/definitioNote: * Estimate


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Mobile Broadband Subscriptions

74.8

29.5

19.8

0

10

20

30

40

50

60

70

80

2007 2008 2009 2010 2011 2012* 2013*

Per 100 inhabitants

Developed

World

Developing

The developed/developing country classifications are based on the UN M49, see: http://www.itu.int/ITU‐D/ict/definitions/regions/index.htmlNote: * EstimateSource: ITU World Telecommunication /ICT Indicators database

Active mobile‐broadband subscriptions per 100 inhabitants, 2007‐2013


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Digital Radio Evolution

http://electronicdesign.com/content/evolution‐lte

1999

2012

2002

2007

1999

2003

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WiFi Standard Evolution

http://www.broadcom.com/docs/press/80211ac_for_Enterprise.pdf

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