1INTRODUCTION

Client

Server

Network

Fig. 1-1. A network with two clients and one server.

Client process Server process

Client machine

Network

Reply

RequestServer machine

Fig. 1-2. The client-server model involves requests and replies.

Fig. 1-3. In a peer-to-peer system there are no fixed clients andservers.

2222222222222222222222222222222222222222222222222222222222222222222222222222222Tag Full name Example2222222222222222222222222222222222222222222222222222222222222222222222222222222B2C Business-to-consumer Ordering books on-line2222222222222222222222222222222222222222222222222222222222222222222222222222222B2B Business-to-business Car manufacturer ordering tires from supplier2222222222222222222222222222222222222222222222222222222222222222222222222222222G2C Government-to-consumer Government distributing tax forms electronically2222222222222222222222222222222222222222222222222222222222222222222222222222222C2C Consumer-to-consumer Auctioning second-hand products on line2222222222222222222222222222222222222222222222222222222222222222222222222222222P2P Peer-to-peer File sharing222222222222222222222222222222222222222222222222222222222222222222222222222222211

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111111111

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Fig. 1-4. Some forms of e-commerce.

22222222222222222222222222222222222222222222222222222222222222Wireless Mobile Applications22222222222222222222222222222222222222222222222222222222222222No No Desktop computers in offices22222222222222222222222222222222222222222222222222222222222222No Yes A notebook computer used in a hotel room22222222222222222222222222222222222222222222222222222222222222Yes No Networks in older, unwired buildings22222222222222222222222222222222222222222222222222222222222222Yes Yes Portable office; PDA for store inventory222222222222222222222222222222222222222222222222222222222222221

111111

1111111

1111111

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Fig. 1-5. Combinations of wireless networks and mobile comput-ing.

1 m Square meter

10 m Room

100 m Building

Campus1 km

City10 km

Interprocessordistance

Processorslocated in same

Example

100 km Country

Continent1000 km

Planet

Personal area network

The Internet

Local area network

Metropolitan area network

Wide area network

10,000 km

Fig. 1-6. Classification of interconnected processors by scale.

Cable Computer

(b)(a)

Computer

Fig. 1-7. Two broadcast networks. (a) Bus. (b) Ring.

Internet

Antenna

Junctionbox

Head end

Fig. 1-8. A metropolitan area network based on cable TV.

Subnet Router

Host

LAN

Fig. 1-9. Relation between hosts on LANs and the subnet.

Sending process Receiving process

Sending host

Router Subnet

Router C makes achoice to forwardpackets to E andnot to D

Packet

Receiving hostDB

A E

C

Fig. 1-10. A stream of packets from sender to receiver.

(a) (b)

Basestation

To wired network

Fig. 1-11. (a) Bluetooth configuration. (b) Wireless LAN.

One telephonecall per computer

(a) (b)

Portablecomputer

Flying router

WiredLAN

Fig. 1-12. (a) Individual mobile computers. (b) A flying LAN.

Layer 5

Layer 4

Layer 3

Layer 2

Layer 1

Host 1

Layer 4/5 interface

Layer 3/4 interface

Layer 2/3 interface

Layer 1/2 interface

Layer 5 protocolLayer 5

Layer 4

Layer 3

Layer 2

Layer 1

Host 2

Layer 4 protocol

Layer 3 protocol

Layer 2 protocol

Layer 1 protocol

Physical medium

Fig. 1-13. Layers, protocols, and interfaces.

I likerabbits

Location A

3

2

1

3

2

1

Location B

Message Philosopher

Translator

Secretary

Informationfor the remotetranslator

Informationfor the remotesecretary

L: DutchIk vindkonijnenleuk

Fax #---L: DutchIk vindkonijnenleuk

J'aimebien les

lapins

L: DutchIk vindkonijnenleuk

Fax #---L: DutchIk vindkonijnenleuk

Fig. 1-14. The philosopher-translator-secretary architecture.

H2 H3 H4 M1 T2 H2 H3 M2 T2 H2 H3 H4 M1 T2 H2 H3 M2 T2

H3 H4 M1 H3 M2 H3 H4 M1 H3 M2

H4 M H4 M

M M

Layer 2protocol

2

Layer 3protocol

Layer 4 protocol

Layer 5 protocol

3

4

5

1

Layer

Source machine Destination machine

Fig. 1-15. Example information flow supporting virtual communi-cation in layer 5.

Reliable message stream Sequence of pages

Reliable byte stream Remote login

Unreliable connection Digitized voice

Unreliable datagram Electronic junk mail

Registered mailAcknowledged datagram

Database queryRequest-reply

Service Example

Connection-oriented

Connection-less

Fig. 1-16. Six different types of service.

222222222222222222222222222222222222222222222222222222222Primitive Meaning222222222222222222222222222222222222222222222222222222222

LISTEN Block waiting for an incoming connection222222222222222222222222222222222222222222222222222222222CONNECT Establish a connection with a waiting peer222222222222222222222222222222222222222222222222222222222RECEIVE Block waiting for an incoming message222222222222222222222222222222222222222222222222222222222SEND Send a message to the peer222222222222222222222222222222222222222222222222222222222DISCONNECT Terminate a connection22222222222222222222222222222222222222222222222222222222211

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Fig. 1-17. Five service primitives for implementing a simpleconnection-oriented service.

(1) Connect request

(2) ACK

(3) Request for data

(4) Reply

(5) Disconnect

(6) Disconnect

Client machine

Protocolstack

KernelOperatingsystem

Drivers Protocolstack

Kernel Drivers

Server machine

Serverprocess

Systemcalls

Clientprocess

Fig. 1-18. Packets sent in a simple client-server interaction on aconnection-oriented network.

Layer k

Layer k + 1

Layer k - 1

Protocol

Service provided by layer k

Layer k

Layer k + 1

Layer k - 1

Fig. 1-19. The relationship between a service and a protocol.

Layer

Presentation

Application

Session

Transport

Network

Data link

Physical

7

6

5

4

3

2

1

Interface

Host A

Name of unitexchanged

APDU

PPDU

SPDU

TPDU

Packet

Frame

Bit

Presentation

Application

Session

Transport

Network

Data link

Physical

Host B

Network Network

Data link Data link

Physical Physical

Router Router

Internal subnet protocol

Application protocol

Presentation protocol

Transport protocol

Session protocol

Communication subnet boundary

Network layer host-router protocol

Data link layer host-router protocolPhysical layer host-router protocol

Fig. 1-20. The OSI reference model.

TCP/IPOSI

Application

Presentation

Session

Transport

Network

Data link

Physical

7

6

5

4

3

2

1

Application

Transport

Internet

Host-to-network

Not presentin the model

Fig. 1-21. The TCP/IP reference model.

ARPANET

Protocols

Networks

TELNET

TCP UDP Transport

LAN

DNS Application

Layer (OSI names)

Packetradio

Physical +data link

SMTP

SATNET

FTP

IP Network

Fig. 1-22. Protocols and networks in the TCP/IP model initially.

Time

Act

ivity

Research

Standards

Billion dollarinvestment

Fig. 1-23. The apocalypse of the two elephants.

222222222222222222225 Application layer222222222222222222224 Transport layer222222222222222222223 Network layer222222222222222222222 Data link layer222222222222222222221 Physical layer222222222222222222221

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Fig. 1-24. The hybrid reference model to be used in this book.

(a)

Tolloffice

Switchingoffice

(b)

Fig. 1-25. (a) Structure of the telephone system. (b) Baran’s pro-posed distributed switching system.

Host-IMPprotocol

Host-host protocol

Source IMP to destination IMP protocol

IMP-IMP protocolIMP-IMP

protocol

Host

IMP

Subnet

Fig. 1-26. The original ARPANET design.

MIT

BBNRANDUCLAUCLA

SRI UTAH ILLINOIS MIT LINCOLN CASE

CARN

HARVARD BURROUGHSBBNRAND

SDC

STAN

UCLA

SRI UTAH

UCSB SDC UCSB

SRI UTAH

UCSB

NCAR GWC LINCOLN CASE

MITRE

ETAC

HARVARD NBSBBNTINKERRAND

SDC

USCAMES

STAN

UCLA

CARN

SRI UTAH

MCCLELLAN

UCSB

ILLINOIS

LINC

RADC

MIT

ILLINOIS MIT

LINC

RADC

UTAH

TINKERRAND

MCCLELLANLBLSRI

AMES TIP

AMES IMPX-PARC

FNWC

UCSB UCSD

STANFORD

CCA

BBN

HARVARDABERDEEN

NBSETAC

ARPA

MITRESAAC

BELVOIRCMU

GWC CASENOAAUSCSDCUCLA

(a)

(d)

(b) (c)

(e)

Fig. 1-27. Growth of the ARPANET. (a) December 1969. (b) July1970. (c) March 1971. (d) April 1972. (e) September 1972.

NSF Supercomputer center

NSF Midlevel network

Both

Fig. 1-28. The NSFNET backbone in 1988.

Server farm

Router

Corporate LAN

Telephonesystem

POP

Client

NAP

BackboneRegional ISP

Fig. 1-29. Overview of the Internet.

Sending process Receiving processVirtual circuit

Sending host

Router Subnet

Receiving host

Fig. 1-30. A virtual circuit.

Bytes 485

User dataHeader

Fig. 1-31. An ATM cell.

CSSAR

TCPMD

Upper layers

Control plane

Layer management

Plane management

User plane

Upper layersSub

layer

Sublay

er

Sublay

er

Sublay

er

CS: Convergence sublayerSAR: Segmentation and reassembly sublayer TC: Transmission convergence sublayerPMD: Physical medium dependent sublayer

ATM adaptation layer

ATM layer

Physical layer

Fig. 1-32. The ATM reference model.

OSIlayer

ATMlayer

ATMsublayer Functionality

AAL

ATM

Physical

Providing the standard interface (convergence)CS

Flow controlCell header generation/extractionVirtual circuit/path managementCell multiplexing/demultiplexing

Cell rate decouplingHeader checksum generation and verificationCell generationPacking/unpacking cells from the enclosing envelopeFrame generation

Segmentation and reassemblySAR

TC

PMD

3/4

2/3

2

1 Bit timingPhysical network access

Fig. 1-33. The ATM layers and sublayers, and their functions.

Ether

TransceiverInterface

cable

Fig. 1-34. Architecture of the original Ethernet.

(a) (b)

To wired network Basestation

Fig. 1-35. (a) Wireless networking with a base station. (b) Ad hocnetworking.

A CB

Rangeof A's radio

Rangeof C's radio

Fig. 1-36. The range of a single radio may not cover the entire sys-tem.

Ethernet

Cell

Base station

Portal

Fig. 1-37. A multicell 802.11 network.

222222222222222222222222222222222222222222222222222222222222222222222Number Topic222222222222222222222222222222222222222222222222222222222222222222222802.1 Overview and architecture of LANs222222222222222222222222222222222222222222222222222222222222222222222802.2 ↓ Logical link control222222222222222222222222222222222222222222222222222222222222222222222802.3 * Ethernet222222222222222222222222222222222222222222222222222222222222222222222802.4 ↓ Token bus (was briefly used in manufacturing plants)222222222222222222222222222222222222222222222222222222222222222222222802.5 Token ring (IBM’s entry into the LAN world)222222222222222222222222222222222222222222222222222222222222222222222802.6 ↓ Dual queue dual bus (early metropolitan area network)222222222222222222222222222222222222222222222222222222222222222222222802.7 ↓ Technical advisory group on broadband technologies222222222222222222222222222222222222222222222222222222222222222222222802.8 † Technical advisory group on fiber optic technologies222222222222222222222222222222222222222222222222222222222222222222222802.9 ↓ Isochronous LANs (for real-time applications)222222222222222222222222222222222222222222222222222222222222222222222802.10 ↓ Virtual LANs and security222222222222222222222222222222222222222222222222222222222222222222222802.11 * Wireless LANs222222222222222222222222222222222222222222222222222222222222222222222802.12 ↓ Demand priority (Hewlett-Packard’s AnyLAN)222222222222222222222222222222222222222222222222222222222222222222222802.13 Unlucky number. Nobody wanted it222222222222222222222222222222222222222222222222222222222222222222222802.14 ↓ Cable modems (defunct: an industry consortium got there first)222222222222222222222222222222222222222222222222222222222222222222222802.15 * Personal area networks (Bluetooth)222222222222222222222222222222222222222222222222222222222222222222222802.16 * Broadband wireless222222222222222222222222222222222222222222222222222222222222222222222802.17 Resilient packet ring22222222222222222222222222222222222222222222222222222222222222222222211

11111111111111111111111

1111111111111111111111111

1111111111111111111111111

Fig. 1-38. The 802 working groups. The important ones aremarked with *. The ones marked with ↓ are hibernating. The onemarked with † gave up and disbanded itself.

222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222Exp. Explicit Prefix Exp. Explicit Prefix22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−3 0.001 milli 103 1,000 Kilo22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−6 0.000001 micro 106 1,000,000 Mega22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−9 0.000000001 nano 109 1,000,000,000 Giga22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−12 0.000000000001 pico 1012 1,000,000,000,000 Tera22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−15 0.000000000000001 femto 1015 1,000,000,000,000,000 Peta22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−18 0.0000000000000000001 atto 1018 1,000,000,000,000,000,000 Exa22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−21 0.0000000000000000000001 zepto 1021 1,000,000,000,000,000,000,000 Zetta22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−24 0.0000000000000000000000001 yocto 1024 ,000,000,000,000,000,000,000 Yotta2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221

111111111111

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Fig. 1-39. The principal metric prefixes.