Ch1 2ed 29_dec03

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Chapter 1 Computer Networks and the Internet Computer Networking: A Top Down Approach Featuring the Internet , 2 nd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2002.

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],[object Object],[object Object]

Chapter 1: roadmap ,[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],[object Object],[object Object],local ISP company network regional ISP router workstation server mobile

“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

What’s the Internet: a service view ,[object Object],[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],Hi Hi TCP connection req All activity in the Internet that involves two or more communicating remote entities is governed by a protocol. (Routing protocols, Congestion Control protocols, media access protocols, etc.) 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]

Network edge: connection-oriented service ,[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]

Network edge: connectionless service ,[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: TDMA and TDMA FDMA frequency time TDMA frequency time 4 users Example:

Network Core: Packet Switching ,[object Object],[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 10 Mbs Ethernet 1.5 Mbs statistical multiplexing queue of packets waiting for output link D E

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

Packet switching versus circuit switching ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Packet-switching: store-and-forward ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],R R R ,[object Object],[object Object],[object Object],[object Object],L

Packet Switching: Message Segmenting ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Packet-switched networks: forwarding ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Virtual Circuit Networks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Table in PS1 A VC network

Datagram Networks ,[object Object],[object Object],[object Object],[object Object],[object Object]

Network Taxonomy ,[object Object],[object Object],[object Object],[object Object],Telecommunication networks Circuit-switched networks FDM TDM Packet-switched networks Networks with VCs Datagram Networks

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],[object Object]

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

Company access: local area networks ,[object Object],[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],[object Object],base station mobile hosts router

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]

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 NAP Tier-1 providers also interconnect at public network access points (NAPs)

Tier-1 ISP: e.g., Sprint Sprint US backbone network

Internet structure: network of networks ,[object Object],[object Object],Tier 1 ISP Tier 1 ISP Tier 1 ISP NAP 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, interconnect at NAP

Internet structure: network of networks ,[object Object],[object Object],Tier 1 ISP Tier 1 ISP Tier 1 ISP NAP 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 NAP 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],A B propagation transmission nodal processing queueing ,[object Object],[object Object],[object Object]

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

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

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

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]

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

Why layering? ,[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

Layering: logical communication ,[object Object],[object Object],[object Object],[object Object],application transport network link physical application transport network link physical application transport network link physical application transport network link physical network link physical

Layering: logical communication ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],application transport network link physical application transport network link physical application transport network link physical application transport network link physical network link physical data data data transport transport ack

Layering: physical communication application transport network link physical application transport network link physical application transport network link physical application transport network link physical network link physical data data

Layering: physical communication Switching Hub application transport network link physical application transport network link physical application transport network link physical application transport network link physical network link physical data data link physical

Protocol layering and data ,[object Object],[object Object],[object Object],source destination message segment datagram frame application transport network link physical application transport network link physical M M M M H t H t H n H t H n H l M M M M H t H t H n H t H n H l

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

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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