INTRODUCTION Client

Server

Network

Fig. 1-1. A network with two clients and one server. Client machine Server machine Request

Network

Client process Server process

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 and servers. 2222222222222222222222222222222222222222222222222222222222222222222222222222222 21 222222222222222222222222222222222222222222222222222222222222222222222222222222Tag1 Full name1 Example 1 1 1 1 1 12222222222222222222222222222222222222222222222222222222222222222222222222222222B2C1 Business-to-consumer1 Ordering books on-line 1 21 222222222222222222222222222222222222222222222222222222222222222222222222222222B2B1 Business-to-business1 Car manufacturer ordering tires from supplier 1 21 222222222222222222222222222222222222222222222222222222222222222222222222222222G2C1 Government-to-consumer1 Government distributing tax forms electronically 1 1 1 1 1 12222222222222222222222222222222222222222222222222222222222222222222222222222222C2C1 Consumer-to-consumer1 Auctioning second-hand products on line 1 21 222222222222222222222222222222222222222222222222222222222222222222222222222222P2P1 Peer-to-peer1 File sharing 1

Fig. 1-4. Some forms of e-commerce. 22222222222222222222222222222222222222222222222222222222222222 222222222222222222222222222222222222222222222222222222222222221 Wireless1 Mobile1 Applications 1 1 1 1 1 122222222222222222222222222222222222222222222222222222222222222No1 No1 Desktop computers in offices 1 222222222222222222222222222222222222222222222222222222222222221 No1 Yes1 A notebook computer used in a hotel room 1 222222222222222222222222222222222222222222222222222222222222221 Yes1 No1 Networks in older, unwired buildings 1 1 1 1 1 222222222222222222222222222222222222222222222222222222222222221 Yes1 Yes1 Portable office; PDA for store inventory 1

Fig. 1-5. Combinations of wireless networks and mobile comput- ing. Interprocessor Processors Example distance located in same

1 m Square meter Personal area network

10 m Room

100 m Building Local area network

1 km Campus

10 km City Metropolitan area network

100 km Country Wide area network 1000 km Continent

10,000 km Planet The Internet

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

Cable Computer

(a) (b)

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

Antenna

Head end

Internet

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. Router Subnet Sending host Receiving host B D A E

C Packet Router C makes a Sending process Receiving process choice to forward packets to E and not to D

Fig. 1-10. A stream of packets from sender to receiver. Base To wired network station

(a) (b)

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

Portable Wired computer LAN One telephone call per computer (a) (b)

Fig. 1-12. (a) Individual mobile computers. (b) A flying LAN. Host 1 Host 2 Layer 5 protocol Layer 5 Layer 5

Layer 4/5 interface Layer 4 protocol Layer 4 Layer 4

Layer 3/4 interface Layer 3 protocol Layer 3 Layer 3

Layer 2/3 interface Layer 2 protocol Layer 2 Layer 2

Layer 1/2 interface Layer 1 protocol Layer 1 Layer 1

Physical medium

Fig. 1-13. Layers, protocols, and interfaces. Location A Location B

I like J'aime Message Philosopher rabbits bien les lapins 3 3

Information L: Dutch for the remote Translator L: Dutch Ik vind translator Ik vind konijnen konijnen 2 2 leuk leuk

Information Fax #--- for the remote Fax #--- L: Dutch secretary Secretary L: Dutch Ik vind Ik vind 1 1 konijnen konijnen leuk leuk

Fig. 1-14. The philosopher-translator-secretary architecture. Layer Layer 5 protocol 5 M M

Layer 4 protocol 4 H4 M H4 M

Layer 3 protocol 3 H3 H4 M1 H3 M2 H3 H4 M1 H3 M2

Layer 2 protocol 2 H2 H3 H4 M1 T2 H2 H3 M2 T2 H2 H3 H4 M1 T2 H2 H3 M2 T2

Source machine Destination machine

Fig. 1-15. Example information flow supporting virtual communication in layer 5. Service Example

Reliable message stream Sequence of pages Connection- oriented Reliable byte stream Remote login

Unreliable connection Digitized voice

Unreliable datagram Electronic junk mail Connection- less Acknowledged datagram Registered mail Request-reply Database query

Fig. 1-16. Six different types of service. 222222222222222222222222222222222222222222222222222222222 2122222222222222222222222222222222222222222222222222222222Primitive1 Meaning 1 1 1 1 1222222222222222222222222222222222222222222222222222222222LISTEN1 Block waiting for an incoming connection 1 2122222222222222222222222222222222222222222222222222222222CONNECT1 Establish a connection with a waiting peer 1 2122222222222222222222222222222222222222222222222222222222RECEIVE1 Block waiting for an incoming message 1 1 1 1 1222222222222222222222222222222222222222222222222222222222SEND1 Send a message to the peer 1 2122222222222222222222222222222222222222222222222222222222DISCONNECT1 Terminate a connection 1

Fig. 1-17. Five service primitives for implementing a simple connection-oriented service. Client machine Server machine (1) Connect request Client (2) ACK process Server (3) Request for data process System (4) Reply calls (5) Disconnect Operating Kernel Protocol Drivers KernelProtocol Drivers system stack (6) Disconnect stack

Fig. 1-18. Packets sent in a simple client-server interaction on a connection-oriented network. Layer k + 1 Layer k + 1

Service provided by layer k

Protocol Layer k Layer k

Layer k - 1 Layer k - 1

Fig. 1-19. The relationship between a service and a protocol. Layer Name of unit exchanged Application protocol 7 Application Application APDU

Interface Presentation protocol 6 Presentation Presentation PPDU

Session protocol 5 Session Session SPDU

Transport protocol 4 Transport Transport TPDU Communication subnet boundary Internal subnet protocol

3 Network Network Network Network Packet

2 Data link Data link Data link Data link Frame

1 Physical Physical Physical Physical Bit Host A Router Router Host B

Network layer host-router protocol Data link layer host-router protocol Physical layer host-router protocol

Fig. 1-20. The OSI reference model. OSI TCP/IP

7 Application Application

6 Presentation Not present in the model 5 Session

4 Transport Transport

3 Network Internet

2 Data link Host-to-network

1 Physical

Fig. 1-21. The TCP/IP reference model. Layer (OSI names)

TELNET FTP SMTP DNS Application

Protocols TCP UDP Transport

IP Network

Packet Physical + Networks ARPANET SATNET radio LAN data link

Fig. 1-22. Protocols and networks in the TCP/IP model initially. Billion dollar Research investment

Standards Activity

Time

Fig. 1-23. The apocalypse of the two elephants. 22222222222222222222 5122222222222222222222 Application layer 1 1 1 4122222222222222222222 Transport layer 1 3122222222222222222222 Network layer 1 2122222222222222222222 Data link layer 1 1 1 1122222222222222222222 Physical layer 1

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

Toll office

(a) (b)

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

Source IMP to destination IMP protocol

IMP-IMP protocol IMP-IMP protocol Subnet

IMP

Fig. 1-26. The original ARPANET design. SRI UTAH SRI UTAH MIT SRI UTAH ILLINOIS MIT LINCOLN CASE

UCSB UCSB SDC UCSB SDC CARN STAN

UCLA UCLA RAND BBN UCLA RAND BBN HARVARD BURROUGHS (a) (b) (c)

SRI LBL MCCLELLAN UTAH ILLINOIS MIT

CCA MCCLELLAN AMES TIP BBN SRI UTAH NCAR GWC LINCOLN CASE AMES IMP HARVARD LINC X-PARC RADC ABERDEEN ILLINOIS CARN STANFORD NBS AMES USC LINC ETAC UCSB MITRE FNWC RAND MIT TINKER STAN SDC ARPA ETAC MITRE RADC UCSB UCSD SAAC UCLA RAND TINKER BBN HARVARD NBS BELVOIR CMU

UCLA SDC USC NOAA GWC CASE (d) (e)

Fig. 1-27. Growth of the ARPANET. (a) December 1969. (b) July 1970. (c) March 1971. (d) April 1972. (e) September 1972. NSF Supercomputer center NSF Midlevel network Both

Fig. 1-28. The NSFNET backbone in 1988. Regional ISP Backbone

POP

NAP Telephone Client Server farm system

Corporate LAN Router

Fig. 1-29. Overview of the Internet. Router Subnet Sending host Receiving host

Sending process Virtual circuit Receiving process

Fig. 1-30. A virtual circuit. Bytes5 48

Header User data

Fig. 1-31. An ATM cell. Plane management

Layer management

Control plane User plane

Upper layers Upper layers CS: Convergence sublayer CS Sublayer ATM adaptation layer Sublayer SAR: Segmentation and SAR reassembly sublayer ATM layer TC: Transmission convergence sublayer Sublayer TC PMD: Physical medium Physical layer Sublayer PMD dependent sublayer

Fig. 1-32. The ATM reference model. OSI ATM ATM layer layer sublayer Functionality

CS Providing the standard interface (convergence) 3/4 AAL SAR Segmentation and reassembly

Flow control Cell header generation/extraction 2/3 ATM Virtual circuit/path management Cell multiplexing/demultiplexing

Cell rate decoupling Header checksum generation and verification 2 TC Cell generation Packing/unpacking cells from the enclosing envelope Frame generation Physical

Bit timing 1 PMD Physical network access

Fig. 1-33. The ATM layers and sublayers, and their functions. Transceiver Interface cable Ether

Fig. 1-34. Architecture of the original Ethernet. Base To wired network station

(a) (b)

Fig. 1-35. (a) Wireless networking with a base station. (b) Ad hoc networking. Range Range of A's of C's radio radio

ACB

Fig. 1-36. The range of a single radio may not cover the entire system. Ethernet Base station Portal

Cell

Fig. 1-37. A multicell 802.11 network. 222222222222222222222222222222222222222222222222222222222222222222222 2222222222222222222222222222222222222222222222222222222222222222222221 Number1 Topic 1 1 1 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.11 Overview and architecture of LANs 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.2 ↓ 1 Logical link control 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.3 *1 Ethernet 1 1 1 1 1222222222222222222222222222222222222222222222222222222222222222222222802.4 ↓ 1 Token bus (was briefly used in manufacturing plants) 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.51 Token ring (IBM’s entry into the LAN world) 1 1 ↓ 1 1 1222222222222222222222222222222222222222222222222222222222222222222222802.6 1 Dual queue dual bus (early metropolitan area network) 1 1222222222222222222222222222222222222222222222222222222222222222222222802.7 ↓ 1 Technical advisory group on broadband technologies 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.8 †1 Technical advisory group on fiber optic technologies 1 1 ↓ 1 1 1222222222222222222222222222222222222222222222222222222222222222222222802.9 1 Isochronous LANs (for real-time applications) 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.10 ↓ 1 Virtual LANs and security 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.11 *1 Wireless LANs 1 1 1 1 1222222222222222222222222222222222222222222222222222222222222222222222802.12 ↓ 1 Demand priority (Hewlett-Packard’s AnyLAN) 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.131 Unlucky number. Nobody wanted it 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.14 ↓ 1 Cable modems (defunct: an industry consortium got there first) 1 1 1 1 1222222222222222222222222222222222222222222222222222222222222222222222802.15 *1 Personal area networks (Bluetooth) 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.16 *1 Broadband wireless 1 1 1 1 2222222222222222222222222222222222222222222222222222222222222222222221 802.171 Resilient packet ring 1

Fig. 1-38. The 802 working groups. The important ones are marked with *. The ones marked with ↓ are hibernating. The one marked with † gave up and disbanded itself. 222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 Exp.1 Explicit1 Prefix1 Exp.1 Explicit1 Prefix 1 1 1 1 1 1 1 1 122222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222210−3 1 0.001 1 milli1 103 1 1,0001 Kilo 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10−6 1 0.0000011 micro1 106 1 1,000,0001 Mega 1 1 − 1 1 1 9 1 1 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10 9 1 0.0000000011 nano1 10 1 1,000,000,0001 Giga 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10−12 1 0.0000000000011 pico1 1012 1 1,000,000,000,0001 Tera 1 1 −15 1 1 1 15 1 1 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10 1 0.0000000000000011 femto1 10 1 1,000,000,000,000,0001 Peta 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10−18 1 0.00000000000000000011 atto1 1018 1 1,000,000,000,000,000,0001 Exa 1 1 −21 1 1 1 21 1 1 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10 1 0.00000000000000000000011 zepto1 10 1 1,000,000,000,000,000,000,0001 Zetta 1 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 10−24 1 0.00000000000000000000000011 yocto1 1024 1 ,000,000,000,000,000,000,0001 Yotta 1

Fig. 1-39. The principal metric prefixes.