Download COM_TOC.PDF

Contents
Preface
1. Communications systems
xix
1
1.1 INTRODUCTION
1
1.2 COMMUNICATIONS MODEL
1
1.3 ELECTRONIC SIGNALS
2
1.4 BANDWIDTH
3
1.5 SIGNAL FREQUENCY CONTENT
4
1.6 MODULATION
1.6.1 Amplitude modulation (AM)
1.6.2 Frequency modulation (FM)
1.6.3 Phase modulation (PM)
1.6.4 Digital modulation
5
5
6
7
7
1.7 FREQUENCY CARRIER
8
1.8 MULTIPLEXING
1.8.1 Frequency-Division Multiplexing (FDM)
1.8.2 Time-Division Multiplexing (TDM)
11
11
12
1.9 NOISE AND SIGNAL DISTORTION
12
1.10 CAPACITY
14
1.11 TRANSMISSION MEDIA
15
1.12 EXERCISE
16
2. Data communications models, networks and standards
21
vii
viii Contents
2.1 COMMUNICATIONS NETWORKS
21
2.2 LOCAL AREA NETWORKS
2.2.1 Why network ?
2.2.2 Maintaining a network
2.2.3 Sharing resources
2.2.4 Sharing disk resources (network file servers)
2.2.5 Electronic mail
2.2.6 Peer-to-peer communication
2.2.7 Remote login
2.2.8 Disadvantages and potential pitfalls of networks
23
23
24
25
25
26
27
28
28
2.3 OSI MODEL
29
2.4 COMMUNICATIONS STANDARDS AND THE OSI MODEL
32
2.5 STANDARDS AGENCIES
33
2.6 NETWORK CABLE TYPES
34
2.7 NETWORK TOPOLOGIES
2.7.1 Star network
2.7.2 Ring network
2.7.3 Bus network
36
36
37
38
2.8 MANCHESTER CODING
39
2.9 EXERCISE
40
2.10 TUTORIAL
43
3. LAN: Ethernet, token ring and FDDI
45
3.1 INTRODUCTION
45
3.2 IEEE STANDARDS
45
3.3 LOGICAL LINK CONTROL
46
3.4 TOKEN RING
3.4.1 Token ring - media access control (MAC)
3.4.2 Token ring maintenance
3.4.3 Token ring multi-station access units (MAU)
48
49
52
53
3.5 ETHERNET
3.5.1 Ethernet - media access control (MAC) layer
3.5.2 Hardware
3.5.3 Ethernet limitations
3.5.4 Ethernet types
3.5.5 Fast Ethernet
3.5.6 Twisted-pair hubs
3.5.7 Interconnection of LANs
55
55
57
59
62
64
64
64
3.6 FIBRE DISTRIBUTED DATA INTERCHANGE (FDDI)
3.6.1 Applications of FDDI networks
3.6.2 FDDI backbone network
66
68
68
3.7 EXERCISE
71
Contents ix
3.8 TUTORIAL
74
4. LAN performance
77
4.1 INTRODUCTION
77
4.2 NETWORK TRAFFIC
77
4.3 IMPROVING NETWORK PERFORMANCE
4.3.1 Minimizing differing Ethernet standards
4.3.2 Fan-out boxes
4.3.3 Segment network with bridges and fan-out boxes
4.3.4 Distributing load
4.3.5 Provide alternative routes
4.3.6 Remove repeaters
4.3.7 Provide local resources
4.3.8 Buffer networks with store and forward bridges
78
79
79
80
81
82
83
84
84
4.4 TUTORIAL
85
5. Transmission Control Protocol (TCP) and Internet Protocol (IP)
87
5.1 INTRODUCTION
87
5.2 TCP/IP GATEWAYS AND HOSTS
89
5.3 FUNCTION OF THE IP PROTOCOL
89
5.4 INTERNET DATAGRAM
91
5.5 TCP/IP INTERNETS
5.5.1 Selecting internet addresses
5.5.2 Format of the IP address
5.5.3 Creating IP addresses with subnet numbers
5.5.4 Specifying subnet masks
93
93
94
96
96
5.6 EXAMPLE NETWORK
99
5.7 DOMAIN NAME SYSTEM
102
5.8 INTERNET NAMING STRUCTURE
103
5.9 DOMAIN NAME SERVER
104
5.10 TCP/IP COMMANDS
5.10.1 ping
5.10.2 ftp (file transfer protocol)
5.10.3 telnet
5.10.4 nslookup
5.10.5 netstat (network statistics)
5.10.6 route
104
104
105
106
107
107
108
5.11 EXERCISE
108
5.12 TUTORIAL
109
6. High-level Data Link Control (HDLC)
111
x Contents
6.1 INTRODUCTION
111
6.2 HDLC PROTOCOL
6.2.1 HDLC modes of operation
6.2.2 HDLC frame format
6.2.3 Information field
6.2.4 Flag field
6.2.5 Address field
6.2.6 Control field
6.2.7 Frame check sequence field
112
112
113
114
114
114
115
118
6.3 TRANSPARENCY
118
6.4 FLOW CONTROL
6.4.1 Link connection
6.4.2 Data flow
118
119
121
6.5 DERIVATIVES OF HDLC
123
6.6 EXERCISE
124
6.7 TUTORIAL
126
7. WAN: X.25 packet switching
127
7.1 INTRODUCTION
127
7.2 PACKET-SWITCHING AND THE OSI MODEL
7.2.1 The physical layer (X.21)
7.2.2 Data link layer (LAPB)
7.2.3 Network (packet) layer
129
129
131
131
7.3 X.25 PACKETS
7.3.1 Packet headers
7.3.2 Packet types
131
131
133
7.4 X.25 PACKET FLOW
7.4.1 Call set-up and clearing
7.4.2 Data transmission and flow control
7.4.3 The delivery bit
135
136
137
139
7.5 PACKET SWITCHING ROUTING
140
7.6 LOGICAL CHANNELS
143
7.7 X.25 NODE ADDRESSING
143
7.8 EXERCISE
146
7.9 TUTORIAL
148
8. Asynchronous communications: RS-232
149
8.1 INTRODUCTION
149
8.2 COMMUNICATIONS TECHNOLOGY
8.2.1 Connecting two nodes
8.2.2 Terminal and communications equipment
149
149
150
Contents xi
8.3 ASCII CHARACTER CODES
8.3.1 Format codes
8.3.2 Communication-control characters
8.3.3 Other codes
8.3.4 Printable character set
150
152
154
154
155
8.4 ELECTRICAL CHARACTERISTICS
8.4.1 Line voltages
8.4.2 Electrical connections
8.4.3 DB25S Connector
8.4.4 DB9S connector
8.4.5 PC connectors
156
156
157
157
157
157
8.5 FRAME FORMAT
8.5.1 Parity
8.5.2 Baud rate
8.5.3 Bit stream timings
159
161
161
162
8.6 STANDARDS
8.6.1 Standards organizations
8.6.2 EIA standard RS-232-C
8.6.3 EIA standard RS-449, RS-422A, RS-423A
8.6.4 EIA standard RS-485
163
163
163
164
164
8.7 LINE DRIVERS
165
8.8 COMMUNICATIONS BETWEEN TWO NODES
8.8.1 Handshaking
8.8.2 RS-232 pocket tester and break-out boxes
8.8.3 RS-232 set-up
8.8.4 Simple no-handshaking communications
8.8.5 Software handshaking
8.8.6 Hardware handshaking
8.8.7 Two-way communications with handshaking
8.8.8 DTE-DCE connections
166
167
168
169
169
170
170
171
172
8.9 PRACTICAL RS-232 PROGRAM
173
8.10 ASYNCHRONOUS PROTOCOLS
173
8.11 EXERCISE
174
8.12 TUTORIAL
176
9. Modems
179
9.1 INTRODUCTION
179
9.2 DIGITAL MODULATION
9.2.1 Frequency shift keying (FSK)
9.2.2 Phase shift keying (PSK)
9.2.3 M-ary modulation
180
181
181
182
9.3 MODEM STANDARDS
183
9.4 MODEM COMMANDS
183
xii Contents
9.5 MODEM CONNECTIONS
185
9.6 MODEM INDICATORS
188
9.7 TUTORIAL
189
10. Pulse coded modulation (PCM)
191
10.1 INTRODUCTION
10.1.1 Sampling theory
10.1.2 Quantization
10.1.3 Coding of samples
10.1.4 Quantization error
191
192
193
193
195
10.2 PCM PARAMETERS
10.2.1 Dynamic range (DR)
10.2.2 Signal-to-noise ratio (SNR)
195
195
196
10.3 SPEECH COMPRESSION
196
10.4 DELTA MODULATION PCM
10.4.1 Adaptive delta modulation PCM
198
200
10.5 DIFFERENTIAL PCM (DPCM)
10.5.1 Adaptive differential PCM (ADPCM)
201
202
10.6 PCM SYSTEMS
202
10.7 ALTERNATIVE MARK INVERSION (AMI) LINE CODE
10.7.1 High density bipolar3 (HDB3) coding
205
206
10.8 TUTORIAL
207
11. Integrated Services Digital Network (ISDN)
209
11.1 INTRODUCTION
209
11.2 ISDN CHANNELS
211
11.3 ISDN PHYSICAL LAYER INTERFACING
11.3.1 Alternative Mark Inversion (AMI) line code
11.3.2 System connections
11.3.3 Frame format
11.3.4 D-channel contention
212
213
213
215
217
11.4 ISDN DATA LINK LAYER
11.4.1 Address field
11.4.2 Control field
11.4.3 Frame check sequence
218
218
220
222
11.5 ISDN NETWORK LAYER
222
11.6 LOCAL AREA NETWORKS CONNECTED TO ISDN NETWORKS
226
11.7 TUTORIAL
227
12. Asynchronous Transfer Mode (ATM)
229
Contents xiii
12.1 INTRODUCTION
229
12.2 STATISTICAL MULTIPLEXING
231
12.3 ATM USER NETWORK INTERFACES (UNI)
231
12.4 ATM CELLS
232
12.5 CONNECTIONS ON AN ATM NETWORK
234
12.6 ATM AND THE OSI MODEL
235
12.7 ATM PHYSICAL LAYER
235
12.8 ATM FLOW CONTROL
236
12.9 RELIABILITY OF AN ATM NETWORK
237
12.10 ATM PERFORMANCE
237
12.11 PRACTICAL ATM NETWORKS
12.11.1 EaStMAN addressing and routing
238
240
12.12 TUTORIAL
241
13. Error control
243
13.1 INTRODUCTION
243
13.2 PARITY
243
13.3 CYCLIC REDUNDANCY CHECKING (CRC)
243
13.4 LONGITUDINAL / VERTICAL REDUNDANCY CHECKS (LRC/VRC)
246
13.5 HAMMING CODE
247
13.6 TUTORIAL
248
14. X-Windows
251
14.1 INTRODUCTION
251
14.2 FUNDAMENTALS OF X
14.2.1 Server
14.2.2 Client
14.2.3 Communications channel
253
253
254
254
14.3 NETWORK ASPECTS OF X
255
14.4 HISTORY OF X
257
14.5 X SYSTEM PROGRAMS
257
14.6 TUTORIAL
258
15. Analysis of digital pulses
261
15.1 INTRODUCTION
261
15.2 REPETITIVE SIGNALS
262
xiv Contents
15.3 WAVE SYMMETRY
15.3.1 Even symmetry
15.3.2 Odd symmetry
15.3.3 Half-wave symmetry
263
263
264
265
15.4 FOURIER SERIES OF A REPETITIVE RECTANGULAR WAVEFORM
265
15.5 EXAMPLES
267
15.6 PROGRAM TO DETERMINE HARMONICS
271
15.7 TUTORIAL
273
16. Transmission lines
277
16.1 INTRODUCTION
277
16.2 EQUIVALENT CIRCUIT
16.2.1 Program to determine characteristic impedance
16.2.2 Propagation coefficient, γ
277
279
280
16.3 SPEED OF PROPAGATION
281
16.4 TRANSMISSION LINE REFLECTIONS
16.4.1 Reflections from resistive termination’s
16.4.2 Reflections at junctions between two transmission lines
16.4.3 Reflections at junctions with two transmission line in parallel
282
282
284
286
16.5 MATCHING TERMINATIONS
287
16.6 OPEN AND SHORT CIRCUIT TERMINATIONS
289
16.7 TUTORIAL
291
17. Optical fibre systems
295
17.1 INTRODUCTION
295
17.2 LIGHT PARAMETERS
17.2.1 Wavelength
17.2.2 Colour
17.2.3 Velocity of Propagation
17.2.4 Refractive index
296
296
296
297
298
17.3 LIGHT EMITTING DIODE (LED)/ INJECTION LASER DIODE (ILD)
298
17.4 PHOTODIODES
299
17.5 FIBRE OPTICS
17.5.1 Introduction
17.5.2 Theory
17.5.3 Losses in fibre optic cables
17.5.4 Fibre optic link
300
300
301
302
303
17.6 TYPICAL OPTICAL FIBRE CHARACTERISTICS
304
17.7 ADVANTAGES OF FIBRE OPTICS OVER COPPER CONDUCTORS
304
17.8 TUTORIAL
306
Contents xv
Appendix A: Practical RS-232 programming
307
A.1 INTRODUCTION
307
A.2 ISOLATED I/O
A.2.1 Inputting a byte
A.2.2 Outputting a byte
307
308
308
A.3 PROGRAMMING THE SERIAL DEVICE
A.3.1 Line Status Register (LSR)
A.3.2 Line Control Register (LCR)
A.3.3 Register addresses
A.3.4 Programming RS232 via DOS
309
311
313
314
315
A.4 PROGRAMS
315
A.5 USING BIOS
321
A.6 TUTORIAL
323
A.7 PROJECTS
A.7.1 Project 1: Half-duplex link
A.7.2 Project 2: Full-duplex link
A.7.3 Project 3: Simulated software handshaking
A.7.4 Project 4: File transfer
327
327
328
328
329
Appendix B: Data communications standards
331
B.1 STANDARDS
331
B.2 INTERNATIONAL ALPHABET NO. 5
332
Appendix C: Data communications connections
335
C.1 RS-232C INTERFACE
335
C.2 RS-449 INTERFACE
336
Appendix D: Ethernet voltages and Fast Ethernet
337
D.1 ETHERNET VOLTAGE LEVELS
337
D.2 FAST ETHERNET AND 100VG-ANYLAN
D.2.1 Fast Ethernet
D.2.2 100VG-Any LAN
D.2.3 Migration from Ethernet to Fast Ethernet or 100VG-AnyLAN
D.2.4 Network performance
339
339
339
340
340
Glossary
341
Common abbreviations
349
Index
353
xvi Contents