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O
KEAAIO 1 APXE IKTYN EIKOINNIN ............................................................................................................................... 9 ............................................................................................................................................ 10
1.1 .................................................... 101.2 H ................................................................. 141.3 .............................................................................................. 141.4 ...................................................................................................... 191.5 .................................................................................................................. 21
1.5.1 ................................................................................................. 211.5.2 ....................................................................................................... 241.5.3 ......................................... 261.5.4 O ............................................................................. 26
................................................................................................. 26` ......................................................................................................... 27
1.6 ............................................................................................................... 291.7 .................................................................................. 311.8 OSI ......................................................................................................................... 35
1.8.1 OSI ............................................................................................. 37 (Application layer) ..................................................................... 37 (Presentation layer) ............................................................... 37 (Session layer) ............................................................................... 37 (Transport layer) ....................................................................... 38 (Network layer) .............................................................................. 38 (Data link layer) ......................................................... 39 (Physical layer) ................................................................................ 39
1.9 ............................................... 401.9.1 ................................................................................................................ 401.9.2 ............................................................................................... 411.9.3 LAN WAN ................................................................................................. 42
1.10 .................................................................................................................................. 431.10.1 ....................................................................................................... 431.10.2 O ........................................................................................... 44
ISO (International Standards Organization) ................................................................ 44ITU (International Telecommunication Union ) ........................................................... 44IETF (Internet Engineering Task Force) ........................................................................ 45IAB (Internet Architecture Board) ................................................................................ 45ETSI (European Telecommunications Standards Institute) ........................................... 45O ( O ) ........................................................... 46
1.11 ......................................................................................... 46 ................................................................................................................................. 47 - ......................................................................................................................... 47 ...................................................................................................................................... 50
KEAAIO 2 EIKOINNIE EOMENN ............................................................................................................................... 51 ............................................................................................................................................ 52
2.1 ............................................. 522.1.1 , ............ 54
, ..................................................................... 572.2 ........................................................................................................ 58
O`
4
2.3 ............................................................... 602.3.1 .................................................... 602.3.2 ............................................ 61
2.4 ........................................................................................... 642.4.1 ................................................................................................ 65
Nyquist ( ) ............................................................... 65 Shannon ( ) ................................................................... 66
2.5 .................................................................................................. 672.5.1 bit .................................................................................................... 672.5.2 ....................................................................................... 672.5.3 .................................................................................. 68
................................................................................................................................. 69 - ......................................................................................................................... 69 ...................................................................................................................................... 70
KEAAIO 3 MEA METAOH .............................................................................................................................. 71 ............................................................................................................................................ 72
3.1 ..................................................................................................................... 723.1.1 ......................................................................................... 72
........................................................................................................ 73O ................................................................................................. 73 O ............................................................................................. 74
3.1.2 ........................................................................................ 76 ............................................................................... 77 ....................................................................... 77 ........................................................................................... 79
3.2 ............................................................................................. 803.2.1 ......................................................... 813.2.2 ............................................................................................................ 843.2.3 ........................................................................................................................ 863.2.4 ....................................................................................................................... 873.2.5 ................................................................................................................................ 88
3.3 ........................................................................................................ 903.3.1 ............................................................................................................ 923.3.2 O ..................................................................................................... 923.3.3 O .................................................................................................................... 933.3.4 .................................................................................. 943.3.5 .......................................................................... 95
................................................................................................................................. 97 ........................................................................................................................ 97 ......................................................................................................................................102
KEAAIO 4 TOIKA IKTYA ........................................................................................................................103 ............................................................................................................................................104
4.1 ........................................................................................................................1044.1.1 (Twisted pair) . ..........................................................104
..................................................................................106 ......................................110
4.1.2 O (Coaxial Cable) .............................................................................1114.1.3 (Fiber optics cable) ....................................................................112
5
. ...................................................113 .....................................................................................115 .....................................................................................................115
4.2 ..................................................................................................1174.3 .....................................................................................................122
4.3.1 (LLC - IEEE 802.2) ...............................................................1234.3.2 IEEE 802.3 ...................................................................125
802.3 ...............................................................................127Ethernet ....................................................................................129
4.3.3 802.4 - (Token Bus) ............1304.3.4 802.5 - K (Token Ring) .......1334.3.5 . ..........................................................................................137
.................................................................................................................................139 - .........................................................................................................................140 ......................................................................................................................................142
KEAAIO 5 TA OMIKA TOIXEIA TN IKTYN ...............................................................................................................................143 ............................................................................................................................................144
5.1 MODEM ....................................................................................................................................1445.1.1 modems ...........................................................................1465.1.2 E DTE DCE ..................................................................................1495.1.3 P (Flow Control) . ........................................................................................1515.1.4 (Error Corection), (Data Compression) ..............1535.1.5 E AT .....................................................................................................................154
5.2 K (Network Interface Cards - NiCs) .....................................................................1545.3 E (Repeaters) .........................................................................................................1555.4 (Bridges) ......................................................................................................................158
5.4.1 K .....................................................................................................160 (Transparent Bridges orSpanning Tree Bridges) ...............................................................................................160
O Spanning Tree .................................................................................162 (Source Route Bridges ) .........................................165 M (Translating Bridges) ..............................................................166 E (Encapsulation Bridges) .........................................................167
5.5 M (Switches) .............................................................................................................1685.6 (Routers) ...........................................................................................................1725.7 E ........................................................................................175
5.7.1 O ...................................................................................................175O ..............................................................................................176E ...................................................................................177O ...............................................................................................177X ....................................................178O .........................................................................................179O ..........................................................................................................179T (Rack) .......................................................................................................181
5.7.2 K ..............................................................................................1815.7.3 T .............................................................................1835.7.4 .....................................................................................1855.7.5 - .......................................................1865.7.6 ...........................................................................................187
.................................................................................................................................190 - .........................................................................................................................191 ......................................................................................................................................194
6
KEAAIO 6 TOIKA IKTYA ...............................................................................................................................195 ............................................................................................................................................196
6.1 ..........................................................................................................1966.2 .........................................................................................1976.3 ................................................................................................................1986.4 .25 ...........................................................................................................................................2006.5 ISDN ..........................................................................................................................................2026.6 Frame Relay ...............................................................................................................................2056.7 ATM ...........................................................................................................................................2086.8 xDSL ..........................................................................................................................................2106.9 E ...........................................................................................................213
6.10 WAN ......................................................................................214 .................................................................................................................................216 ........................................................................................................................216 ......................................................................................................................................218
KEAAIO 7 IAIKTYH - INTERNET ...............................................................................................................................219 ............................................................................................................................................220
7.1 .......................................................................................................................2207.1.1 .................................................................................................................220
7.2 TCP/IP .....................................................................................................................2247.2.1 TCP/IP ..................................................................................2247.2.2 OSI TCP/IP .....................................................................................................2267.2.3 TCP/IP .....................230
7.3 TCP ......................................................................................................................2337.3.1 TCP ................................................................................................................237
7.4 UDP .....................................................................................................................2407.5 P .........................................................................................................................2427.6 ....................................................................................................................247
7.6.1 (Media Access Control, MAC ) .......................................................................247
7.6.2 IP ................................................................................................................2497.6.3 ...............................................................................251
7.7 ARP ......................................................................................................................2547.8 O (Domain Name System, DNS) .................................................259
7.8.1 O DNS ...........................................................................................2627.9 ............................................................................................................................264
7.9.1 TCP/IP .....................................................................................2667.9.2 ......................................................................................................2697.9.3 ...................................................................................................2707.9.4 .................................................................................................272
7.10 .....................................................................................................2757.10.1 (Routing Information Protocol, RIP) ...........2777.10.2 E (Exterior Gateway Protocol, EGP) .................................278
7.11 ..........................................................................................................2797.11.1 .................................................................................................................2797.11.2 ...........................................................279
.........................................................................................279 (File Transfer Protocol, FTP) ...............................281 (elecommunications `etwork, Telnet) ............................283 (World Wide Web, WWW ) ..........................................................283
7
.................................................................................................285 TCP/IP (Intranets) .......................................286 ....................................................................................286 ..................................................287 ..................288 ................................................................................................288
.................................................................................................................................289 ........................................................................................................................290 ......................................................................................................................................295
KEAAIO 8 IAXEIPIH KAI AAEIA IKTYOYo o o .......................................................................................................................297 ............................................................................................................................................298
8.1 o ...................................................................................................................2988.1.1 (Configuration Management) ..................................................2998.1.2 o o (Performance Management) .....................................3008.1.3 (Fault Management) .................................................................3028.1.4 o (Accounting Management) .............................................................3028.1.5 (Security Management) ..............................................................303
8.2 ...............................................................................................................3038.2.1 CMIP ..............................................................................................................3048.2.2 SNMP ..........................................................................................305
o o o SNMP ...................................................................307B (Management Information Base, MIB) ...................308 II, RMON, RMON2 .............................................................................310
8.2.3 o ............................................................................................3148.3 ....................................................................................................................314
8.3.1 oo ................................................................................................3148.3.2 Ooo ..................................................................................................3178.3.3 oo ....................................................................................................3188.3.4 .......................................................................................................3208.3.5 oo .................................................................................................3258.3.6 o o ...............................................................................................327
.................................................................................................................................329 - .........................................................................................................................329o ......................................................................................................................................330
KEAAIO 9 O POO TN IKTYN THN KOINNIA TH HPOOPIKHo o ...............................................................................................................................331 ............................................................................................................................................332
9.1 O o oo ........................................................................................3329.1.1 H .......................................3329.1.2 E - .........................................................................3339.1.3 E .......................................................................335
9.2 o o o ......................................................................3369.3 Ooo o ..................................................................................3409.4 o ..........................................................................................................345
.................................................................................................................................348 - .........................................................................................................................349o ......................................................................................................................................349
APAPTHMAO ............................................................................................................................................351
8
T O X O I K E A A I O Y
. :
` , . ` . ` . ` , -
(OSI). ` .
K E A A I O 1
AAPPXXEE IIKKTTYYNN EEIIKKOOIINNNNIINN
O
, , . - . .
1.1 -
19 , 20 3 - .
- . , . , .
, . , 1 , . , - 2 2 , , 3x2=6 3x2/2=3 . , 3 3 , , - 4x3=12 4x3/2=6 ( 1-1). , -
10 T E X N O O I A I K T Y N E I K O I N N I N
1-1 4, 5
, ` , `-1 - `(`-1)/2 . 1000 , - 999 499.500 !
, , - (telephone network), - - . - , - , , -, - .
. - . , , -, (data networks).
, - , - (resources) ( 1-2).
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 11
T
E
1-2
, , , . O , , -, , . , , , , , , . , , , : . O , - . O , - .
. , - , . , -, , - , , (. , ) - , (Internet).
. ,, , , . - ( 1-3):
12 T E X N O O I A I K T Y N E I K O I N N I N
Scanner
Fax
Printer
Modem
Server
Data
()
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 13
()
30
1-3 O () () Y , ,
- , 300 .. , - . 3 2,5 , 1 . - 5 . O - 1-1. , - .
ITOPIKO HMEIMA
1.2
. - , - . - :
( ) ( ).
, . -
, , , . , -
, . , , , .
- . - , . - - , , .
1.3
. , ,
14 T E X N O O I A I K T Y N E I K O I N N I N
1-1 O , 300 ..
O OO1 2 3 4 5
1 2 3 ` O4 5
O
O
O
. - , - ( , .). - , , , , . 1 - , 2 Mbits (2Mbps).
. , , - - (printer server). , - (file server). , .. Internet, , - (e-mail), -, (file transfer), - , .
, , - . , . , 2, - bits. , - , , bits .
, bits . - - .
, .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 15
, , , , , . .
E
, bits . bit ( ), bits (0 1 ). -, . O , , - . , -, , .
, bits - . , , , , . , - . -, , , , .
O .
(connection oriented service), - ,
16 T E X N O O I A I K T Y N E I K O I N N I N
bits
1-4 bit
1 2 3 1 3 2
1-5
, . .
(connectionless service), - , , , . -, . -, . -. . , , , . - - , . , -, , - . , ( ).
, . - bits ,
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 17
1 2 3 1 2 3
1-6
1 2 3 3 1
1-7
(.. , ). - , - (.. - ). , , (.. , ).
18 T E X N O O I A I K T Y N E I K O I N N I N
K
b
its
1 2
1
2
3 4
3
4
1-8 ,
. , - . bits, , . (- ). , , - . O bits - bit (, -). , , , , , .
- .
E
1.4 1.1 -
. , - -. .
(switching), , , - , -. , , , -, - .
O , , . 1-9 . O , - , , , - . O , . . , , , 1. , 3 6 4 6, - . , - 1-9 : -
, . , - , .
, , . , - , -. , - .
, - , - .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 19
(multiplexing) , , - . , . 1-10 ( -). , (multiplexer). O (demultiplexer). , - . O (-) - . O , , .
20 T E X N O O I A I K T Y N E I K O I N N I N
K1 K5
E
K2
B
A
K3
K4 K6
1-9 , ,
,
A
1-10
1.5
, (circuit switching) - (packet switching). , () , .
1.5.1
, - , . . , - 1-11: . O
. , (-) ( ). -, K1, K1 K3, K3 K6 K6 . , , .
. , , - . , . , , , , , -, . , - ( ) -K1, K1, K1-K3, - K3, K3-K6, K6 K6-.
. . O , , , , . . -
. , - , , . -, , 100% (- ).
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 21
22 T E X N O O I A I K T Y N E I K O I N N I N
K1 K5
E
K2
B
A
K3
A
K4 K6
K1 K5
E
K2
B
A
K3
M
K4 K6
K1 K5
E
K2
B
A
K3
T
K4 K6
1-11 O
, - . , , . , , - ( - , , , , ).
(Public Switched Telephone Network, PSTN). , - , - ( ) modems, .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 23
K T
1-12
, - . - -. , . , - . .
1.5.2
, - , , , - ( , ,.), , . , , , - . - , : ,
, , -. , , .
, - . , - , . - . , , -
, . bytes. - 1000 bytes. (destination address) (sequence number). , (Packet Switching Node, PSN), , . O , , .
1-13. O . - 1, . - , , 2. . , , . -, , . , - (store and forward).
24 T E X N O O I A I K T Y N E I K O I N N I N
- : . ,
- , , , -, . . , , ., , - .
-. , , .
-, . , - , - ( ). , , .
. , , , - . , -, - .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 25
K1 K5
E
K2
B
A
K3
K4
K6
E
E
E
E
1-13 . , ,
,
1.5.3
, - , . - - , . -, , .
, , , -. , , , - , - . , - .
1.5.4 O
, - , , , , -. , , , . : .
(datagram), -
. , . , (.. ) .
. -, , -
26 T E X N O O I A I K T Y N E I K O I N N I N
, A T M (Asynchro-nous Transfer Mode, ), , - .
, .
- ( ) , . , , , . , - .
, -, - .
` (virtual circuit),
, . .
- , .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 27
K1 K5
E
K2
B
A
K3
K4 K6
=
=
1-14 .
(Internet, TCP/IP).
- , - - . , . O - - . , , , .
28 T E X N O O I A I K T Y N E I K O I N N I N
- .25 (.. Hellaspac).
, - , , , . , , , . , , -. , , .
K1 K5
E
K2
B
A
K3
K4K6
=
=
1-15 .
1.6 1.4,
( ), . , , . , , . , , , . , ., , (300 Hz 3400 Hz) . , , ( ), .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 29
X
f1 K 1
X
FDM
f2 K 2
f3 K 3
f4 K 4
f5 K 5
X
K
1
TDM
K
2
K
3
K
4
K
5
K
1
K
2
K
3
K
4
K
5
K
1
K
2
1-16 O
: .
(frequency division multiplexing, FDM) . - . , 1-16. - , , .
(time division multiplexing, TDM) (timeslots). - . , . - . . .
- (synchronous TDM). FDM TDM -, - . , - - , - (statistical time division multiplexing, statistical TDM).
TDM, , , , - . - . , (buffers) . , -. , -. , , -. , -, , - . , . , , ( 1-17).
30 T E X N O O I A I K T Y N E I K O I N N I N
1.7 ,
, , . , - , -, . , . E - , , , - .
, - , (communicationprotocol) (protocol). , - (entities), . , , , , e-mail. , , , - . , , - . - . , , - . , , - .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 31
K
A B
1-17
, , , , .
T , - .
O , , , (networkarchitecture). M, , (layers) (levels). . O , , . , , , , .
M :
. E ,
.
32 T E X N O O I A I K T Y N E I K O I N N I N
H , ., , , , , , , .
H , , , . A, , .
E
O , , - , , - (interface) . , , - . O - -
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 33
1-18
M , , , , .
.
, . A (System Network Architecture, SNA) IBM, OSI ( - OSI) ISO, TCP/IP, .
34 T E X N O O I A I K T Y N E I K O I N N I N
6 / 7
Y A Y B
7E 7 E 7
5 / 6
6E 6 E 6
4 / 5
5E 5 E 5
3 / 4
4E 4 E 4
2 / 3
3E 3 E 3
1 / 2
2E 2 E 2
1E 1 E 1
1-19 ,
, .
E
1.8 OSIH -
. 1984, O (International Standard Organi-
zation, ISO) , -. (Open Systems Interconnection reference model, OSI RM).
, (layering), ISO. O . , . , . , , - . , .
O ISO , . , , OSI, , , . . , - - .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 35
(open systems) , - . , - .
E
OSI , , - .
E
36 T E X N O O I A I K T Y N E I K O I N N I N
E E .
E .
E E ,, .
E M , .
E A . .
E E . M , .
EA bits.
011101010010110111010100101011001001001101010111010010110111010101001011010111011010110010100011000010010100111101110111000101010010100100001001010010011101001111101001001110110100110100110100100100111100
1-2 OSI
. . - , , Internet ().
, - , ( OTE). O , , .
1.9.3 LAN WAN
LAN WAN , - , - . , , LAN WAN. , , . , LAN -, , , , -
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 33
H
A
I
1.21. .
1.8.1 OSI
(Application layer) OSI . -
- . - . , . (e-mail), (file transfer), (database access), .
(Presentation layer)
. - . , . , , - , .
- .
(Session layer) , -
, , - , (session). , , .
, - : . . ( -
). ( , .
.)., , ,
, : .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 37
, - .
, - . , - .
( - ).` ,
. .
(Transport layer)
OSI. ., , - , (-), - . - , - .
O , , - , -, ( , ). , (.. - , , , ), .
.
(Network layer)O
. , - . - - (, , , ).
38 T E X N O O I A I K T Y N E I K O I N N I N
- , . , - , - (congestion).
- .
(Data link layer)
. (data frames). O (header) (trailer), , , -. , - , ,, -, .
, , - - ( ).
(Physical layer) OSI .
bits -, , , (, ).
, , - . , , - , - , -, , ..
bits, 0 1, bit, - .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 39
, bits (0 1) - , - bytes 8 bits ASCII 7 bits.
1.9
, , , .
1.9.1
40 T E X N O O I A I K T Y N E I K O I N N I N
4 .
1-20 ,
(Local Area Networks, LANs) , - (.. ). (10 100 Mbps), - . , -. , , , -, .
- , , . 4 .
1.9.2
(Wide Area Networks, WANs) - (.. , , ). , - (dial-up) ( - O), (dedicated leased lines), (.. Hellaspac). - ( ).
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 41
- , -. , , , - (multiple access). , . , /, . . , .
6 .
. . - , , Internet ().
, - , ( OTE). O , , .
1.9.3 LAN WAN
LAN WAN , - , - . , , LAN WAN. , , . , LAN -, , , , -
42 T E X N O O I A I K T Y N E I K O I N N I N
H
A
I
1-21
, . , LAN - , WAN, , , ( , , .).
1.10 1.10.1
, - - . O , , - , .
, , - . , , -. , - . , - .
, - (standards) . : . . ,
. , , : de jure (),
, de facto ( ), , .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 43
O Pentium Intel , SPARC(Scalable Processor ARChitecture) . O- . , - , MVS , , IBM PC UNIX . Windows Mi-crosoft , Linux - .
1.10.2 O
-, , - . O -.
, , :
ISO (International Standards Organization) O O 1946
89 . ISO , , O. O O , OSI (OSI Reference Model), HDLC ..
ITU (International Telecommunication Union ) ,
-. , -, . 1992, -
44 T E X N O O I A I K T Y N E I K O I N N I N
TCP/IP de facto RFCs(Request For Comments). - , , , Internet, - OSI, .
. , , .
www.iso.ch
ITU, CCITT (ConsultativeCommittee for International Telegraph and Telephone). 1992, CCITT - . 1992 - , 1976 , 1980 , 1984 ,1988 1992 . (recommendations) V, - , X, , , ISDN, Q, , ..
IETF (Internet Engineering Task Force) Internet. -
, , , - , - Internet. -, , ..
IAB (Internet Architecture Board) , -
, Internet. IETF, , - Internet /- RFCs (Request for Comments).
ETSI (European Telecommunications Standards Institute) (ETSI ) -
. 1989 . - .
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 45
www.itu.org
www.ietf.org
www.iab.org
O ( O ) ,
. ISO, ETSI.
1.11
. -, , . - , - , , , - . , , , (Integrated Services Digital Network, ISDN).
ISDN , - .
ISDN -. , - ISDN, . , -.
ISDN . , ISDN. , ISDN (narrowband ISDN), 64Kbps . , ISDN (broadband ISDN B-ISDN), - ( 150 Mbps) -. , -ISDN , .
46 T E X N O O I A I K T Y N E I K O I N N I N
www.etsi.org
www.elot.gr
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 47
ISDN 6.
-, , , video., , -, , video (video-on-demand), (video conferencing) , . , , - : , 109 bits, 4 64 Kbps, 11 1,5bps 7 150 Mbps.
, - . , , , , . - , - .
. , , , , . - .
-, . -, - 1984, O ISO (International Standard Organization) (Open Systems Interconnection
ANAKEAAIH
48 T E X N O O I A I K T Y N E I K O I N N I N
reference model OSI RM). OSI, , -. OSI : , , -, , , .
, , , (Local Area Networks LANs) (Wide Area Networks - WANs).
, ISO, ITU, O .. (standards), , - , -, .
- (integrated servicesdigital network ISDN), - , .
1. 20 , . ;
2. ;
3. ;
4. , - ;
5. ;
6. :. .. .
7. - ;
8. , , , - , :. .. .
E A
K E A A I O 1 A P X E I K T Y N E I K O I N N I N 49
9. , 4 kHz. - 60 kHz 108 kHz;
10. 30 TDM. . - 125 sec, .
11. - .
12. , , ..........................
13. ;
14. ;
15. , :. .. .. .. 3 .
16. OSI ...........................
17. OSI , :. .. O
.. .
18. .............. .
19. OSI -:. .. .
20. ;
21. ;. .
1. ., , 1994.2. Ramteke T., Networks, Prentice Hall, 1994.3. Stallings W., Data & Computer Communications, 6th ed., Prentice Hall, 2000.4. Tanenbaum A., Computer Networks, Prentice Hall, 1996.5. Walrand J., , . , 1997.
50 T E X N O O I A I K T Y N E I K O I N N I N
. .. .
22. .
23. ...............................
24. -;
25. de jure -:. .. .
26. ;
27. OSI :. ETSI.. ISO.. O.. IAB.
28. , ..................... , .
29. ISDN;
T O X O I K E A A I O Y
:
` , -.
` . ` -
. ` . ` ,
. ` , ,
.
K E A A I O 2
EEIIKKOOIINNNNIIEE EEOOMMEENNNN
, (-
, , ) . - , , . - .
2.1
, , - .
. - . . - (), . - , . . .
, . -
52 T E X N O O I A I K T Y N E I K O I N N I N
AB HHK AB HHK AB HHK
A
A
2-1
. - .
, - , . , . , , . , .
K E A A I O 2 E I K O I N N I E E O M E N N 53
X
X
X
X
A
2-2 H
O : -, .
, . - . - .
E
. , ( -) . , - 1000 Hz 1 500 Hz 0. , - , .
: . . , . , , -
, , , video, . ,
, . , -
, . , .
2.1.1 ,
( ) -: . , (time-domain), (frequency-domain).
, , (2-3), ( 2-4) - . , . , , f T=1/f. 2-4 , - , .
54 T E X N O O I A I K T Y N E I K O I N N I N
, , - . - , . , 2-5 s(t), , f - 3f. 2-6 S(f) .
K E A A I O 2 E I K O I N N I E E O M E N N 55
T
X
T
X
2-3
T
X
()
() M
T=1/f
H T
T
X
T
X
T
X
T=1/f
2-4 ,
56 T E X N O O I A I K T Y N E I K O I N N I N
T1=T
S1(t)
A
T2=T/3
S2(t)
()
S(t)
()
()
A/4
X
X
X
2-5 () s1(t)=sin(2ft): f () s2(t)=sin(2(3f)t): 3f
() s(t)=sin(2ft)+sin(2(3f)t) s(t) s1(t) s2(t)
, , - s(t), , S(f), - .
, , ,
, . , (bandwidth) -. , , , , , 4 kHz (2-7), - , 100 Hz 10 kHz ( 2-8). , , , , . , 100 Hz 3400 Hz .
K E A A I O 2 E I K O I N N I E E O M E N N 57
Sf
f 2f 3f 5f4f
2-6 s(t)=sin(2ft)+sin(2(3f)t)
Sf
4 KHz
2-7 A
2. 2 -
() . -, , , - , .O , :
58 T E X N O O I A I K T Y N E I K O I N N I N
Sf
100 Hz 10 kHz
2-8 A
X()
X()
2-9 () ()
, - . , , - , , . ( 2-9). , , , - .
,
. , , , - . O , , - (Amplitude Modulation, AM), - (Frequency Modulation, FM) (Phase Modulation, PM).
, , video, ,
. (Pulse Code Modulation, PCM), , bits.
, modem, ,
, - . O , , - (Amplitude Shift Keying, ASK), (Frequency Shift Keying, FSK) (Phase Shift Keying,PSK). , (, , ).
, O
, 0 1.
K E A A I O 2 E I K O I N N I E E O M E N N 59
T
A ( )
A
Modem
( )
A
A (
)
(
)
ISDN
K. PCM
2-10 O
2.3 2.3.1
O - () . - , - .
, - 2-11. :1. . , , . -
, .2. . ,
, , . , -, , - . , modem ( ) , (.. ) , .
3. . (.. - , ) .
4. . . , modem - , - ( , ).
5. . .
60 T E X N O O I A I K T Y N E I K O I N N I N
()
()
M
Modem H/Y H/YModem
2-11 () A ()
2.3.2
, , - , ( 2-12).
O - ( ), , , -. , , .
/ . , -, , - . , (), (man-made) . -, , , , .
, - . , -, , .
, , , - ( 2-12):
K E A A I O 2 E I K O I N N I E E O M E N N 61
K-
K-
K
A-
A-
A-
A
+
2-12
.O , ,
. O , , , , ., , , . - .
/ . ,
r . O 0 1, - , . s bits . O , , . .., - 5 bits, 00000 11111, 32 . r=10 symbols/sec, s=50 bits/sec.
, . O - - , .
/ . -
. , - , , , . O - , bits - . bits , - bits, .
62 T E X N O O I A I K T Y N E I K O I N N I N
, . , - bits - bits . , bits, , bits, bits .
O bits, - . , . O , , .
( - ), , - - .
, .O
( ), . - , -, - .
, , , .
. -
. , - , . -, - , , - , . , , , , -. , , , (noise). - (Signal to Noise Ratio, SNR), .
K E A A I O 2 E I K O I N N I E E O M E N N 63
2.4 , ,
, ,
64 T E X N O O I A I K T Y N E I K O I N N I N
( 2-13). , - . ASCII, bits10010010. , - bit 0 bits , 1, . , 100100101. O -, - . , , , -, . , .. .
K-
K-
K
A-
A-
A-
A
A
A
10010010
10010010
100100101
100100101
+
2-13
( ). , - bit (bit errors), 1 0 0 1. , . O - , -, . - 3 .
- - .
2.4.1
, - , . O , - , (channel capacity).
Nyquist ( )O Nyquist ,
, 2. ( ), ( ) 2 bps.
, -, , . , bits. , , - 4 ( ), 2 bits., , , - :
C = 2Blog2M
K E A A I O 2 E I K O I N N I E E O M E N N 65
modem, - . , =3400 Hz. , , bits , 2=6800 bps.
, , , . , , -, , 2. , .
Shannon ( ) . ,
, . . - , (Signal to Noise Ratio, SNR), . , SNR , , - . O SNR db (decibels) :
, S/N, C , (data) , Shannon-Hartley:
C = Blog2 (1 + S/N) bits/sec
C . , - , C.
(SNR)db =10 log10
66 T E X N O O I A I K T Y N E I K O I N N I N
1000 , SNR 30 db.
2.5 -
. , , .
2.5.1 bit
O bit (bit rate), bits, -. bits (bits per second, bps), kbps (103 bps) Mbps (106 bps). , (0 1), bit rate R , bit :
2.5.2
O (baud rate), (bauds), , , modem. O baud rate bits (bit rate). , -, bit , baud rate bit rate. , , bit rate baud rate , (baud) bits.
, modem baud 100 baud 2 bits, bit rate 200 bps. , 2 bits 4 , modem 4 - (bauds).
R = 1T
K E A A I O 2 E I K O I N N I E E O M E N N 67
~ 3 kHz S/N = 103, 30.000 bits/sec, Shannon-Hartley :
C = 3.000 log2 (1 + 1000) bits/sec = 30.000 bits/sec
2.5.3
, bits, , , .. bits - (start stop bit). , , - (information rate), bps, , -, bit.
68 T E X N O O I A I K T Y N E I K O I N N I N
X (msec)10 20 30 40 50 60
0 1 0 1 1 0 0 0 1 1 1 0
P 200 bps
Bits
00
01
10
11
X (msec)
P 100 baud
T/2
T
2-14 P bit .K bit
10 bits, 3 bits , bit 300 bps. 70%. , 300 bps 0,7 =210 bps.
K E A A I O 2 E I K O I N N I E E O M E N N 69
. , , . , .
, -. , - .
, , . , , , , , , , , .
Nyquist Shannon - - .
- , bit (bit rate), (baud rate) (information rate) .
ANAKEAAIH
1. :. .. .. .
2. ;
3. , :. 5 kHz.. 5 kHz 10 kHz.. 19 kHz 23 53 kHz.
4. .
E A
1. ., ., , 1997.2. Roden M., Analog and Digital Communication Systems, 4th ed., Prentice Hall, 1996.3. Stallings W., Data & Computer Communications, 6th ed., Prentice Hall, 2000.4. Walrand J., , . , 1997.
70 T E X N O O I A I K T Y N E I K O I N N I N
5. , - :. .. .. ISDN.. CD.. CD.
. .
6. .
7. O - , , ,
8. , - :. .. .. .
9. O , - :. .. .. .
10. - =4kHz. . 4
( );. S/N=1000, -
. ;
11. O (baud rate):. bit.. bit.. -
.
T O X O I K E A A I O Y
:
` , . ` . ` . ` , . ` , -
.
K E A A I O 3
MMEEAA MMEETTAAOOHH
. , , , . .
O , , - , - .
. - , - . - , - . - .
3.1
3.1.1
, - .
, . ,
72 T E X N O O I A I K T Y N E I K O I N N I N
O , , - , , . - , , -, , , ..
ITOPIKO HMEIMA
, . , , . ( ), , -, . O . , , , . , , -, .
O -
, - , -. , , - . , . - , , .
, , , - . ` ,, , . - , - , .
O . O
, 3-2.
K E A A I O 3 M E A M E T A O H 73
X M
3-1
, - - . - , , , . , - . (bandwidth, BW), - . , .
O . -
MHz, . - . , 9.9 Gbps - , , Britannica .
- , -. O - ( )
74 T E X N O O I A I K T Y N E I K O I N N I N
()
/
3-2 O
. O : (), .
, , - . , - .
, , , , , , - , - . , , 30.000 , - . BSFOCS, , O- , SEA ME WE 3 (South East Asia MiddleEast West Europe), (, . ), (, , ) - (, ) , ADRIA1, (), (Durres) (Dubrovnik).
O , , -, , , , -, , , , , .
K E A A I O 3 M E A M E T A O H 75
3-3 O
3.1.2
O -, , , , , - .
, -, , / , - . , , , - , ,, . , , , , - .
, . - , , , - , - , . , . , , - ( , - ).
- .
76 T E X N O O I A I K T Y N E I K O I N N I N
K
O E
3-4
O
(GHz). , 2 40 GHz, - 2 18 GHz. , Mbps ( 2 GHz) - Mbps ( 20 GHz).
O - . - , -. 40-50 .
O , , , , - - .
O -
(), . O -, (uplink) (downlink). O - -, , , ( 3-5). H (broadcast) (broadcasting services), .
K E A A I O 3 M E A M E T A O H 77
E
35.880 km
A Z K Z
3-5
O 1958, , Early Bird, 6 1965. O , , -, 10 . - , - . , - , .
-, 35.880 Km - (11.040 /). , - , . , , . O , , - , 3-6. - 120, , 3-7. O , , 4 6 GHz, 12-14 GHz 19-29 GHz.
78 T E X N O O I A I K T Y N E I K O I N N I N
A B
E A B
A B
A B
3-6
,
- . , . , , -, , , , . O , , 30 900 MHz. , ( -). , , - .
1946. , - . . , , - .
-. ,
K E A A I O 3 M E A M E T A O H 79
3-7
(), - (1,5-13). . O - 900 1800 MHz . -, . O - , . - ( 900 1800 MHz) - . - , , . , - , - , .
, - , -. , , - . . , - - . , , , . , ( -, Kbps) .
3.2
- .
O , , , , - , -. , , -, .
O , , , , , , . O -, ,
80 T E X N O O I A I K T Y N E I K O I N N I N
, , - , - , . . , , - , , - , . - , . - , .
3.2.1
- (, ) , .
, , . - . (R) -, , , , .
, (RL) (Rc) . (RL) -, , - . , . , - , - , - .
K E A A I O 3 M E A M E T A O H 81
, , :
E
(Rc) , . , , , , - . , - . , , , . - , .
O , (Z), :
Z2 = R2 + (RL RC)2
, , . , , , - , . , , , - .
, , . - 3-8, . () 3 Volt (Ri) (R) 300 , :
UR = ER/(R+Ri) = 3 300/600 = 1,5 V
P = UR 2/R = 7,5 mW.
, , R 150 , :
82 T E X N O O I A I K T Y N E I K O I N N I N
, . , - . , , , . , - .
UR = ER/(R + Ri) = 3 150/450 = 1 V
P = UR 2/R = 6,6 mW
600 , :
UR = ER/(R + Ri) = 3 600/900 = 2 V
P = UR 2/R = 6,6 mW
, , , - .
, , , . , , , . , - , - . , -, , . , . , , - (). -, .
K E A A I O 3 M E A M E T A O H 83
Ri
M
RE
3-8
3.2.2
. - , , bits (bit errors), .
, , . -, . 3-9 - ( dB ) . , -, . (amplitude distortion). , , . , , , .
84 T E X N O O I A I K T Y N E I K O I N N I N
0
A (dB)
(KHz)
3
6
9
12
0 0,5 1
K
1,5 2 2,5 3 3,5 415
3-9
, , , , . - , - .
E
. . , - , , -, , ( ). (groupdelay).
3-10 - . ,, 1800 Hz. - sec 1800 Hz.
2 , - -. , , - ( 3-11).
K E A A I O 3 M E A M E T A O H 85
4000
(sec)
(KHz)
3000
2000
1000
0
0 0,5 1 1,5 2 2,5 3 3,5 4
3-10
3.2.3
, .
O : , -
, , , . , -
, .. . , -
. , -
: , . -
-. , - .
, , .
, -, ().
, , . - ( ).
, . ,
. dBm,
. , - . -
86 T E X N O O I A I K T Y N E I K O I N N I N
H(f)
MT
x(t) y(t)
3-11
dB. - , 20 dB - , 30 dB .
3.2.4
. - , , - . , -, , , , . - .
, . , - . , ,, , .
, - . -, - x y ( 3-12). x y . - x , - y . x y.
K E A A I O 3 M E A M E T A O H 87
A x
M
y
B
T KT
3-12
. , , , - .
- , . -, 50 -, 49 . 3-13 , - , . , , 1 3 , , - 30 3 Mbps.
3.2.5
. , - , .
3-14, - -. O , . - . ,
88 T E X N O O I A I K T Y N E I K O I N N I N
M X
(Mbps)
A (Km)
100
10
0 1 2 3 4 5 61
3-13 ,
, . .
, - . , - . , , . , , , - ( 3-15).
K E A A I O 3 M E A M E T A O H 89
T T
K
HH
3-14 H
H
T K T
T K
H
3-15
3.3 O -
. . , , , . , , - . , , - .
, , :
: - , . . , , () , , , .
: , , - . , (). , , .
: , ( ), - .
90 T E X N O O I A I K T Y N E I K O I N N I N
: -, , .
: - . , -
, , - . , - . , . , , - , . .
, , , . O , , . , -, , , . , , , TeraHertz (1012 Hertz). , - bit .
, -, -, ( ) . , - .
, -, .
K E A A I O 3 M E A M E T A O H 91
3.3.1
KHz -, . -, . , , - . H , . -, . , , - .
- , -. , .
3.3.2 O
, - -. , , , . , , -, , , . , , . , , . , - , .
92 T E X N O O I A I K T Y N E I K O I N N I N
1. 2. M K3.
: 1. E 2. M
3.3.3 O
O - , , .
O , - ( Gbps). - 2 10 Gbps, 20, 40 50 Gbps. , Tbps. , , . - , -, - , - . - , - . , . , , 1000 500 4000 , , , 45 . , , - . , - ( , .).
, , , - , - . , - , ,
K E A A I O 3 M E A M E T A O H 93
1. , 2. , 3. ,
: 1. 2. 3.
, . , -, , , - . , , , .
3.3.4
O - . , . , , - .
O , 6 Gbps, 1,5 45 Mbps. , , , . . - , - , , , . , -
94 T E X N O O I A I K T Y N E I K O I N N I N
1. Gbps2. (Wave division
Multiplexing) Tbps.3. 4. 5. 6. 7.
: 1. , -
2. 3.
, , .
3.3.5
O - , , . , , , (broadcasting).
. 3-1 -, 3-2 .
K E A A I O 3 M E A M E T A O H 95
1. 2. 3.
: 1. 2. 3. 4. ,
1. 2. 45 Mbps,
.3. , -
4. , -
:
1. 2. 3. -
.4.
96 T E X N O O I A I K T Y N E I K O I N N I N
3-1
O O / / /
/ / / /
3-2
O
, , ,
, ,
K E A A I O 3 M E A M E T A O H 97
. . , , - - .
, , :
-, , , . , , , . - .
ANAKEAAIH
1. ;
2. ;
3. ;
4. , - ;
5. ;
6. , ;
7. ;
8. ;
9. ;
10. ;
11. ;
E A
98 T E X N O O I A I K T Y N E I K O I N N I N
12. ;
13. ;
14. , - ;
15. : O O
16. - ; . . .
17. ;. ` . O . .
18. ;. . . O .
19. ; . . . ,
20. - ;. O . O .
21. ;. . . .
K E A A I O 3 M E A M E T A O H 99
22. - ;. 2-40 KHz. 2-40 MHz. 2-40 GHz. 2-40 THz
23. ;. . . .
24. , ;. ` . ` . `
25. ; . . .
26. ; a. b. c.
27. ; . . .
28. , ;. . .
29. :. . .
100 T E X N O O I A I K T Y N E I K O I N N I N
30. , :. .
31. O :. . . .
32. -: . . . .
33. :
,
,
,
34. :
35. : .
K E A A I O 3 M E A M E T A O H 101
. .
36. - :. . . . .
37. :. O . . O . .
38. :. O . .
39. : . O . . O .
40. : . O . O .
41. - ( ):. O . O .
1. A A. ., Y,
4 , 19972. ., , 19943. ., O : , 19894. ., , ,
19845. ., , 19886. Maurice Gagnaire, An Overview of Broad-Band Access Technologies, Proceedings
of the IEEE, Vol.85, No. 12, Dec. 19977. Tanenbaum A., , , 19928. The International Engineering Consortium, Fiber - Optic Technology Tutorial,
http://www.iec.org
102 T E X N O O I A I K T Y N E I K O I N N I N
T O X O I K E A A I O Y
:
` , . ` , -
, . ` . ` . ` , -
. ` . ` , I
H H M, (IEEE), E E . N IEEE E
M.
K E A A I O 4
TTOOIIKKAA IIKKTTYYAA
.
, - .
-, , - , .
4.1 , ,
: . O . .
4.1.1 (Twisted pair).
. . O - . , .
-
104 T E X N O O I A I K T Y N E I K O I N N I N
4-1
UTP (Unshilded Twisted Pair). . -
. - .
FTP ( Foiled Twisted Pair). -
.
. . - , (drain wire).
STP (Shilded Twisted Pair). -
.
. -
K E A A I O 4 T O I K A I K T Y A 105
E 4-1 K UTP
E 4-2 K FTP
. - (drain wire) - .
(S/FTP,S/STP). , -
. S/FTP (Shilded/Foiled Twisted Pair), SSTP (Screened/ShildedTwisted Pair), .
X
, , (solidwire) , (stranded wire), -, (twist pitch), - (insulation type) - (sheath material).
106 T E X N O O I A I K T Y N E I K O I N N I N
E 4-3 K STP
E 4-4 () K S/FTP () K S/STP
()
()
O - , /TIA 568- , ( / , ElectronicIndustry Association / Telecommunications Industry Association), - . -, .
- .
, - . , .
, . - , , . - I M ( Balanced Transmission Line).-, . , , - .
, , - .
K E A A I O 4 T O I K A I K T Y A 107
+1V+N+N +N +2V
1V+N
E O
4-2 .
/ 568-, 4 25 mm 5 13 mm.
, -
(attenuation). , , -: (), ,
. O 24AWG ( American Wire Gauge), ( 1 AWG = 7,35 mm). 100 Ohm.
, , . .
(skin effect), , - . - , , . - . , , -
, -. EIA/ TIA 568-, , , 100 .
dB - .
- , . , - . , , - , - .
(Near End Cross Talk, NEXT) ,
, , (Near End Cross alk, NEXT). NEXT , . , , -
108 T E X N O O I A I K T Y N E I K O I N N I N
. .
dB. O dB, .
-. (Far End Cross alk, FEXT).
(Attenuation to Cross Talk Ratio,ACR)
O (NEXT) NEXT , , .
, ACR, - .
K E A A I O 4 T O I K A I K T Y A 109
FEXT
E
4-4 (FEXT)
NEXT
E
4-3 (NEXT)
K
/ 568- A (UTP), - .
(cat) 3,4,5, , , NEXT, ACR - , - .
O . -.
5e, - , - (UTP), - 5 ( - ) .
, - 5e.
110 T E X N O O I A I K T Y N E I K O I N N I N
(dB/305 m) NEXT (dB/305m)Cat 3 Cat 4 Cat 5 Cat 3 Cat 4 Cat 5
1 MHz 7,8 6,5 6,3 41 56 6210 MHz 30 22 20 26 41 4720 MHz - 31 28 - 36 4262,5 MHz - - 36 - - 35100 MHz - - 67 - - 32
(dB/100 m) NEXT (dB/100m) ACR (dB/100m)1 MHz 2 65,3 63,310 MHz 6,5 50,3 43,820 MHz 9,3 45,8 36,562,5 MHz 17 38,4 21,4100 MHz 22 35,3 13,3160 MHz 28,6 32,3 3,7
4-2 X 5e
4-1 X
UTP 5 5e - - 1Gbps/sec.
, , 6, 7, 8. , , 250 MHz,600 MHz, 900MHz. O S/STP.
O , . .
4.1.2 O (Coaxial Cable)
, - . , - , - .
. - , , . - . , (drain wire). , , - .
: Thicknet () Thinnet ().
.
K E A A I O 4 T O I K A I K T Y A 111
E
K
4-5 O
, . , - .
, , . , 10Mbps 500 Thicknet 185 Thinnet .
- , Thicknet Thinnet, . - .
4.1.3 (Fiber optics cable)
. , , - . , 5Km 10 Gbps.
4-6.
, - . - , clading buffer. , , (cladding) (- 4-6). .
112 T E X N O O I A I K T Y N E I K O I N N I N
O
E
E
4-6 H
, , , . - - .
T .
LED (LightEmmiting Diode) LASER (Light Amplification by Stimulated Emission offRadiation), , , 800nm 1.500nm.
O , , . . ( Multimode fiber optics)
O - () - (cladding). O 10-6 . O 50m/ 125m, 62,5/125, 85/125 100/140. O , , 62,5/ 125. 900m. - , 4-7, 4-8. (multimode), - , -. O : (step index) (graded index).
O (step index).
. , 4-7.
K E A A I O 4 T O I K A I K T Y A 113
, . , . O, , , - ,graded index, -, .
O (graded index)O
. - . , 4-8.
(single mode fiber optics). -. , , . 4-9.
114 T E X N O O I A I K T Y N E I K O I N N I N
4-8 O (graded index)
4-9 (single mode fiber optic)
4-7 O (step index)
5m 10m 8,3 m.
X .
O - , , , , . 1310 nm 1550 nm. 850 nm 1300 nm. , , - .
O - . O - , - 3Km, 10 Km.
, , , . , - , . , . , , . , - LED, - LASER. T 62,5/125 3,5 dB/Km 850 nm 1.0dB/Km 1300nm. - 0,5 dB/Km 1310 nm 0,4 dB/Km 1550nm.
T .
1 36 . - full-duplex .
. ,
. , -. -, . , , . - Tight Buffer. 4-10() .
K E A A I O 4 T O I K A I K T Y A 115
, (Optical patch cords). , - . 4-10() - .
116 T E X N O O I A I K T Y N E I K O I N N I N
E
E (Buffer)
O
E
4-10 () ( Tight Buffer)
E
E (Buffer)
O
4-10 () O Patch cord
, , . Loose Buffer. 4-11 .
4.2
. , - . : (.. ) . , ,
.
K E A A I O 4 T O I K A I K T Y A 117
O
E
E (Buffer)
4-11 (Loose Buffer)
.
118 T E X N O O I A I K T Y N E I K O I N N I N
E E E
A A T
E
E
E
E E
E E
K M E
E
E
E
E E
()
()
()
4-12 () () ()
. . (Broadcast) (Multicast).
, . , , .
, , ( ).
O , , - .
.O :
, ( 4-12).
(Bus Topology)O - . - (taps). , , . O , , , , . , , . , , - , , - . , - , - , ., .
(Ring Topology) - . -
K E A A I O 4 T O I K A I K T Y A 119
, - , . ,, .
E
"" - , . . -, , .
(Star Topology)O . - -, , . H , . , , -, , , . , - , , , , - .O :
I. O -. O -.
II. O .
III. O .
120 T E X N O O I A I K T Y N E I K O I N N I N
-. - . , , - .
E
K E A A I O 4 T O I K A I K T Y A 121
E
E
A
E
E
E
E
E E
E E
K M E
A
K M E
A
K M E()
()
4-13 () ()
, . O -: -.
E
. -. , . , , , , .
. .
4.3
. , , , . ,, , - . (Institute of Electrical and Electronic Engineers, IE-EE) (EuropeanComputer Manufacturing Association, ECMA) - OSI.
, - OSI. . . .
O , 802, (LAN) (MAN) . -, ( MAN , ). 6 - -. , . 802. - .
802, OSI - : - (Logical Link Control, LLC) (Medium Access Control, MAC).
122 T E X N O O I A I K T Y N E I K O I N N I N
802.2. 802.3,4 5 .
4.3.1 (LLC - IEEE 802.2)
802.2 LLC. , LLC -, 802.3,4 5. O LLC . - " " (SAPs - Service AccessPoints), LLC. LLC - .
LLC : (Unacknoledged con-
nectionless service). - . , -, . , , , . - -
K E A A I O 4 T O I K A I K T Y A 123
E
E
(LLC)
M (MAC)
E
OSI IEEE 802
M M
4-14 OSI IEEE 8
, .
(Acknoledged conne-ctionless service). , , - - . -, - (point to point).
(Connection oriented service). LLC. , -. -. . O . : -, . - , -
124 T E X N O O I A I K T Y N E I K O I N N I N
E
E
E
A ()
E
B
A
E
A
E X
Y(E)
Y(E
)
XY(E)
E
A ()
E
B
A
E
A
4-15 A
. . - .
. O LLC - : (request), (indication), (response) (confirm). 4-15.
LLC -. , . O .
: - bit. - . bit HDLC ( Y , High Level Data Link Control, ). HDLC 802.2.
4.3.2 802.3
802.3 , .
802.3 MAC. 802.3 - MAC LLC . MAC . O , - 802.3, " - " (Carrier SenseMultiple Access with Collision Detection - CSMA/CD). - . -, .
CSMA/CD. CSMA/CDO CSMA/CD -
K E A A I O 4 T O I K A I K T Y A 125
ethernet. To Ethernet Xerox 1970 802.3. Ethernet ( I II). Ethernet ( ) 802.3, 802.3. , Ethernet , CSMA/CD Ethernet 802.3.O : , , (). , , . , . , , , , - (collision). , , - , , , . , - . , , , . , , CSMA/CD, . , -, -, , -, , , , , ( - ) . , , . - , . - , t0. -, , , to, - . , t0+-. , . O , , 2-,
126 T E X N O O I A I K T Y N E I K O I N N I N
, . , , , 2 . , , -, . CSMA/CD , - 1518 (bytes), 64 . , - , . - , 0 Volt, , -. , - Manchester. Manchester, -: bit 0 -, bit 1 , () 0 Volts. +0,85 Volts, -0,85 Volts.
, , - , , . , , -. , .
B IEEE 802.3.
- , 802.3 - . - 802.3.
K E A A I O 4 T O I K A I K T Y A 127
Manchester0
0
+
0
tB
1 0 1 1 0 1
4-16 Manchester
:XBase/BroadbandY
: MbpsBase / Broadband , (segment) 802.3
.
Ethernet II 10base5. 802.3 -
, , (Fiber Ethernet). : 10Base-F. 10Base -F: Fiber Ethernet
10Base-F FOIRL (Fiber Optic Inter-Repeater Link), . - 62.5/125 m LEDs. - 10Base-FL (HUBs) 2m. , ( 2Km),
128 T E X N O O I A I K T Y N E I K O I N N I N
10Base5 O 10 Mbps 500 m
50 Ohm thick 10Base2 O 10 Mbps 185 m
50 Ohm thin (RG-58)
1Base5 1 Mbps 250 m
(UTP)10BaseT 10 Mbps 100 m
(UTP)
10Broad36 O 10 Mbps 3600 m 75 Ohm
( ). ,, , - (.. - ).
Ethernet .
802.3. , , 802.3 . , : 802.3u (Fast Ethernet) 802.3z (Gigabit Ethernet) Fast Ethernet
Fast Ethernet 100Mbps. , Fast Ethernet, . , - : 100Base-TX, 100Base-FX 100Base-T4. 100Base-TX: UTP (-
) 5, STP (). 100 . - , -. , , -, . , -, .
100Base-T4: UTP 3 . - , - . - , . 100 . , () . 100-BaseT4, 100BaseTX, - .
100Base-FX: (62.5/125m) . - 412 half-dublex 2 - full-dublex. - 25 .
Gigabit Ethernet gigabit Ethernet IEEE 802.3z 802.3. -
K E A A I O 4 T O I K A I K T Y A 129
1000 Mbps. 5 (cat5 enhance). 1000BaseT cat 5e.To gigabit Ethernet . 62.5 m 1000BaseSX 275 , 50 m 550 . 1000BaseLX 62.5 50 microns 550 9 m 5km.
- gigabit switches .
4.3.3 802.4 - (Token Bus)
802.3, , , General Motors, . O - 802.3. - . (). - - .
802.4, (token bus). , token bus, MAP (Manufacturing Automation Protocol, AK), General Motors. - , 802.4 , - .
75 Ohm - (RG6, RG11, RG59, JT4750J 0.5 1 -
130 T E X N O O I A I K T Y N E I K O I N N I N