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Chapter 1 Introduction Computer Networking: A Top Down Approach , 4 th edition. Jim Kurose, Keith Ross Addison-Wesley, July 2007. ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Chapter 1: Introduction ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Chapter 1: roadmap ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

What’s the Internet: “nuts and bolts” view ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Home network Institutional network Mobile network Global ISP Regional ISP router PC server wireless laptop cellular handheld wired links access points

“Cool” internet appliances World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html IP picture frame http://www.ceiva.com/ Web-enabled toaster + weather forecaster Internet phones

What’s the Internet: “nuts and bolts” view ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Home network Institutional network Mobile network Global ISP Regional ISP

What’s the Internet: a service view ,[object Object],[object Object],[object Object],[object Object],[object Object]

What’s a protocol? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

What’s a protocol? ,[object Object],Q: Other human protocols? Hi Hi TCP connection request Got the time? 2:00 TCP connection response Get http://www.awl.com/kurose-ross <file> time

A closer look at network structure: ,[object Object],[object Object],[object Object],[object Object],[object Object]

The network edge: ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],client/server peer-peer

Access networks and physical media ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Residential access: point to point access ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Residential access: cable modems ,[object Object],[object Object],[object Object],[object Object],[object Object]

Residential access: cable modems Diagram: http://www.cabledatacomnews.com/cmic/diagram.html

Cable Network Architecture: Overview home cable headend cable distribution network (simplified) Typically 500 to 5,000 homes

Cable Network Architecture: Overview home cable headend cable distribution network server(s)

Cable Network Architecture: Overview home cable headend cable distribution network (simplified)

Cable Network Architecture: Overview home cable headend cable distribution network FDM (more shortly): Channels V I D E O V I D E O V I D E O V I D E O V I D E O V I D E O D A T A D A T A C O N T R O L 1 2 3 4 5 6 7 8 9

Company access: local area networks ,[object Object],[object Object],[object Object],[object Object],[object Object]

Wireless access networks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],base station mobile hosts router

Home networks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],wireless access point wireless laptops router/ firewall cable modem to/from cable headend Ethernet

Physical Media ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Physical Media: coax, fiber ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Physical media: radio ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Network Core ,[object Object],[object Object],[object Object],[object Object]

Network Core: Circuit Switching ,[object Object],[object Object],[object Object],[object Object],[object Object]

Network Core: Circuit Switching ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Circuit Switching: FDM and TDM FDM frequency time TDM frequency time 4 users Example:

Numerical example ,[object Object],[object Object],[object Object],[object Object],[object Object]

Network Core: Packet Switching ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Bandwidth division into “pieces” Dedicated allocation Resource reservation

Packet Switching: Statistical Multiplexing ,[object Object],[object Object],A B C 100 Mb/s Ethernet 1.5 Mb/s statistical multiplexing queue of packets waiting for output link D E

Packet-switching: store-and-forward ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],R R R L more on delay shortly …

Packet switching versus circuit switching ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],N users 1 Mbps link Q: how did we get value 0.0004?

Packet switching versus circuit switching ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Q: human analogies of reserved resources (circuit switching) versus on-demand allocation (packet-switching)?

Internet structure: network of networks ,[object Object],[object Object],[object Object],Tier 1 ISP Tier 1 ISP Tier 1 ISP Tier-1 providers interconnect (peer) privately

Tier-1 ISP: e.g., Sprint … to/from customers peering to/from backbone …. … … … POP: point-of-presence

Internet structure: network of networks ,[object Object],[object Object],Tier 1 ISP Tier 1 ISP Tier 1 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP ,[object Object],[object Object],[object Object],Tier-2 ISPs also peer privately with each other.

Internet structure: network of networks ,[object Object],[object Object],Tier 1 ISP Tier 1 ISP Tier 1 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP local ISP local ISP local ISP local ISP local ISP Tier 3 ISP local ISP local ISP local ISP Local and tier- 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet

Internet structure: network of networks ,[object Object],Tier 1 ISP Tier 1 ISP Tier 1 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP local ISP local ISP local ISP local ISP local ISP Tier 3 ISP local ISP local ISP local ISP

How do loss and delay occur? ,[object Object],[object Object],[object Object],A B packet being transmitted (delay) packets queueing (delay) free (available) buffers: arriving packets dropped ( loss ) if no free buffers

Four sources of packet delay ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],A B propagation transmission nodal processing queueing

Delay in packet-switched networks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Note: s and R are very different quantities! A B propagation transmission nodal processing queueing

Caravan analogy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],toll booth toll booth ten-car caravan 100 km 100 km

Caravan analogy (more) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],toll booth toll booth ten-car caravan 100 km 100 km

Nodal delay ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Queueing delay (revisited) ,[object Object],[object Object],[object Object],traffic intensity = La/R ,[object Object],[object Object],[object Object]

“ Real” Internet delays and routes ,[object Object],[object Object],[object Object],[object Object],[object Object],3 probes 3 probes 3 probes

“ Real” Internet delays and routes 1 cs-gw (128.119.240.254) 1 ms 1 ms 2 ms 2 border1-rt-fa5-1-0.gw.umass.edu (128.119.3.145) 1 ms 1 ms 2 ms 3 cht-vbns.gw.umass.edu (128.119.3.130) 6 ms 5 ms 5 ms 4 jn1-at1-0-0-19.wor.vbns.net (204.147.132.129) 16 ms 11 ms 13 ms 5 jn1-so7-0-0-0.wae.vbns.net (204.147.136.136) 21 ms 18 ms 18 ms 6 abilene-vbns.abilene.ucaid.edu (198.32.11.9) 22 ms 18 ms 22 ms 7 nycm-wash.abilene.ucaid.edu (198.32.8.46) 22 ms 22 ms 22 ms 8 62.40.103.253 (62.40.103.253) 104 ms 109 ms 106 ms 9 de2-1.de1.de.geant.net (62.40.96.129) 109 ms 102 ms 104 ms 10 de.fr1.fr.geant.net (62.40.96.50) 113 ms 121 ms 114 ms 11 renater-gw.fr1.fr.geant.net (62.40.103.54) 112 ms 114 ms 112 ms 12 nio-n2.cssi.renater.fr (193.51.206.13) 111 ms 114 ms 116 ms 13 nice.cssi.renater.fr (195.220.98.102) 123 ms 125 ms 124 ms 14 r3t2-nice.cssi.renater.fr (195.220.98.110) 126 ms 126 ms 124 ms 15 eurecom-valbonne.r3t2.ft.net (193.48.50.54) 135 ms 128 ms 133 ms 16 194.214.211.25 (194.214.211.25) 126 ms 128 ms 126 ms 17 * * * 18 * * * 19 fantasia.eurecom.fr (193.55.113.142) 132 ms 128 ms 136 ms traceroute: gaia.cs.umass.edu to www.eurecom.fr Three delay measurements from gaia.cs.umass.edu to cs-gw.cs.umass.edu * means no response (probe lost, router not replying) trans-oceanic link

Packet loss ,[object Object],[object Object],[object Object],A B packet being transmitted packet arriving to full buffer is lost buffer (waiting area)

Throughput ,[object Object],[object Object],[object Object],server, with file of F bits to send to client link capacity R s bits/sec link capacity R c bits/sec server sends bits (fluid) into pipe pipe that can carry fluid at rate R s bits/sec) pipe that can carry fluid at rate R c bits/sec)

Throughput (more) ,[object Object],R s bits/sec R c bits/sec ,[object Object],R s bits/sec R c bits/sec link on end-end path that constrains end-end throughput bottleneck link

Throughput: Internet scenario ,[object Object],[object Object],10 connections (fairly) share backbone bottleneck link R bits/sec R s R s R s R c R c R c R

Protocol “Layers” ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Organization of air travel ,[object Object],ticket (purchase) baggage (check) gates (load) runway takeoff airplane routing ticket (complain) baggage (claim) gates (unload) runway landing airplane routing airplane routing

Layering of airline functionality ,[object Object],[object Object],[object Object],ticket (purchase) baggage (check) gates (load) runway (takeoff) airplane routing departure airport arrival airport intermediate air-traffic control centers airplane routing airplane routing ticket (complain) baggage (claim gates (unload) runway (land) airplane routing ticket baggage gate takeoff/landing airplane routing

Why layering? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Internet protocol stack ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],application transport network link physical

ISO/OSI reference model ,[object Object],[object Object],[object Object],[object Object],[object Object],application presentation session transport network link physical

Encapsulation source application transport network link physical segment datagram destination application transport network link physical router switch message frame H t H n M H t H t H n H l M H t H n M H t M M network link physical link physical H t H n H l M H t H n M H t H n M H t H n H l M M H t M H n

Network Security ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Bad guys can put malware into hosts via Internet ,[object Object],[object Object],[object Object],[object Object]

Bad guys can put malware into hosts via Internet ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Sapphire Worm: aggregate scans/sec in first 5 minutes of outbreak (CAIDA, UWisc data)

Bad guys can attack servers and network infrastructure ,[object Object],[object Object],[object Object],[object Object],target

The bad guys can sniff packets ,[object Object],[object Object],[object Object],A B C ,[object Object],src:B dest:A payload

The bad guys can use false source addresses ,[object Object],A B C src:B dest:A payload

The bad guys can record and playback ,[object Object],[object Object],A B C src:B dest:A user: B; password: foo

Network Security ,[object Object],[object Object],[object Object]

Internet History ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],1961-1972: Early packet-switching principles

Internet History ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],1972-1980: Internetworking, new and proprietary nets

Internet History ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],1980-1990: new protocols, a proliferation of networks

Internet History ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],1990, 2000’s: commercialization, the Web, new apps

Internet History ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction: Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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