1. Postacademic Interuniversity Course in Information Technology – Module C1p1 Chapter 1 Evolution of Communication Networks

2. Postacademic Interuniversity Course in Information Technology – Module C1p2 Contents The 19th century telecommunications –Telegraph - Telephone –Digital vs. analog communications The voice networks & the data networks The electronics revolution (1960-1980) –Digital sound –Mainframe computers with remote access –The first unification : ISDN –Local area networks –Wide area and local area networks integration The Internet –The research project –The universal computer communications medium –The successful unification ?

3. Postacademic Interuniversity Course in Information Technology – Module C1p3 Contents The 19th century telecommunications –Telegraph - Telephone –Digital vs. analog communications The voice networks & the data networks The electronics revolution (1960-1980) –Digital sound –Mainframe computers with remote access –The first unification : ISDN –Local area networks –Wide area and local area networks integration The Internet –The research project –The universal computer communications medium –The successful unification ?

4. Postacademic Interuniversity Course in Information Technology – Module C1p4 The Chappe Telegraph (Claude Chappe, 1763-1805) 92 out of 256 (= 4*8*8) positions represented characters. Integrity of message could be restored at each relay station In 1844, 534 relays linked Paris with 29 cities, covering in total 5000 Km.

5. Postacademic Interuniversity Course in Information Technology – Module C1p5 The Morse Telegraph Samuel Morse, 1791-1872 First electrical telegraph demonstrated in 1837

6. Postacademic Interuniversity Course in Information Technology – Module C1p6 The Morse Telegraph Signal strength can be restored by means of electromechanical relays connecting separate telegraphic circuits. On land lines, unlimited distances can be covered, without increasing significantly the error rate.

7. Postacademic Interuniversity Course in Information Technology – Module C1p7 The Telephone Graham Bell, 1876.

8. Postacademic Interuniversity Course in Information Technology – Module C1p8 Analog vs. Digital Almost infinite number of states External perturbations can not be distinguished from original signal (superposed noise) Information degrades along the lines Finite, small, number of states Most external perturbations can be distinguished from original signal Information can be restored in relays 6:12 Analog Digital

9. Postacademic Interuniversity Course in Information Technology – Module C1p9 Digital Techniques Representation of numbers in electronic devices ? Binary numbers (base 2) are used. A binary digit (bit) can be represented by a switch: –Value 0 : switch open –Value 1 : switch closed A number with n bits can take 2 n different values –2 bits : 4 combinations 00 01 10 11 –3 bits : 8 combinations 000 001 010 011 100 101 110 111 –8 bits (= 1 byte) 256 combinations –16 bits: 65 536 combinations –24 bits: 16 777 216 combinations –32 bits: 4 294 967 296 combinations

10. Postacademic Interuniversity Course in Information Technology – Module C1p10 Contents The 19th century telecommunications –Telegraph - Telephone –Digital vs. analog communications The voice networks & the data networks The electronics revolution (1960-1980) –Digital sound –Mainframe computers with remote access –The first unification : ISDN –Local area networks –Wide area and local area networks integration The Internet –The research project –The universal computer communications medium –The successful unification ?

11. Postacademic Interuniversity Course in Information Technology – Module C1p11 The Telephone Full mesh network n*(n-1) 2

12. Postacademic Interuniversity Course in Information Technology – Module C1p12 The Telephone With central switchboard n

13. Postacademic Interuniversity Course in Information Technology – Module C1p13 Automatic Exchange (1920) Conversation with switch operator replaced by signaling protocol - Voice: analog - Signaling: digital

14. Postacademic Interuniversity Course in Information Technology – Module C1p14 The Telephone Network PABX SW PABX SW Trunk lines

15. Postacademic Interuniversity Course in Information Technology – Module C1p15 Telex Networks (1930-1990) Morse code replaced by Baudot or ASCII code

16. Postacademic Interuniversity Course in Information Technology – Module C1p16 Alphabetical Codes

17. Postacademic Interuniversity Course in Information Technology – Module C1p17 ASCII Character Set (7 bit) 000 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 ! “ # $ % & ‘ ( ) * +, -. / 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 0 1 2 3 4 5 6 7 8 9 : ; < = > ? 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 @ A B C D E F G H I J K L M N O 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 P Q R S T U V W X Y Z [ \ ] ^ _ 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 ` a b c d e f g h i j k l m n o p q r s t u v w x y z k { | } del 032 033 034 035 036 037 038 040 041 042 043 044 045 046 047 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 nul soh stx etx eot enq ack bel bs ht lf vt ff cr so si dle dc1 dc2 dc3 dc4 nak syn etb can em sub esc fs gs rs us

18. Postacademic Interuniversity Course in Information Technology – Module C1p18 Unicode (16 bit) FFFF = 65537 0000 ASCII Latin,Greek,Cyrillic, and Armenian Arabic and Hebrew Indic Punctuation, math, graphics Chinese / Japanese / Korean symbols Unified Chinese / Japanese / Korean ideographs Private applications

19. Postacademic Interuniversity Course in Information Technology – Module C1p19 The Dual Networks Voice Network Analog+Digital Data Network Digital

20. Postacademic Interuniversity Course in Information Technology – Module C1p20 Contents The 19th century telecommunications –Telegraph - Telephone –Digital vs. analog communications The voice networks & the data networks The electronics revolution (1960-1980) –Digital sound –Mainframe computers with remote access –The first unification : ISDN –Local area networks –Wide area and local area networks integration The Internet –The research project –The universal computer communications medium –The successful unification ?

21. Postacademic Interuniversity Course in Information Technology – Module C1p21 The Electronics Revolution (1970-1980) Integrated circuits (“chips”) make electronics affordable. Mainframe computers become very powerful Mini & microcomputers become very popular Digital techniques offer better price/performance for sound applications

22. Postacademic Interuniversity Course in Information Technology – Module C1p22 Music Records Analog Digital (CD) (44100 measurements/s) -096 +057 +164 +210 +219 +216 +165 -003 -117 -183 -138 -067

23. Postacademic Interuniversity Course in Information Technology – Module C1p23 Records with a scratch Analog Digital (CD) -096 +057 +164 +210 XXXX -117 -183 -138 -067 +210 +145 +079 +014 -052 -117

24. Postacademic Interuniversity Course in Information Technology – Module C1p24 Remote Computers Access (1970) Star Network Mainframe Computer Dumb Terminals

25. Postacademic Interuniversity Course in Information Technology – Module C1p25 I S D N The first attempt to integrate voice and data Integrated Services Digital Network Voice digitized at 64 Kb/s (8000 samples/s, 8 bit) Truly digital signaling A telephone connection = a 64 Kb/s digital link +A 64 Kb/s digital link is excellent for connecting a terminal to a mainframe computer -Connection time billing inadequate for data  ISDN widely used for telephony  ISDN marginal for data applications

26. Postacademic Interuniversity Course in Information Technology – Module C1p26 Local Area Networks (1970) LAN’s initially introduced for Printer sharing File sharing...

27. Postacademic Interuniversity Course in Information Technology – Module C1p27 The Dual Screen Desk (1980) WAN LAN

28. Postacademic Interuniversity Course in Information Technology – Module C1p28 LAN-WAN Integration (1990) WAN LAN

29. Postacademic Interuniversity Course in Information Technology – Module C1p29 Client - Server Systems Interconnection Network (LANs+WAN)

30. Postacademic Interuniversity Course in Information Technology – Module C1p30 Client - Server Systems Benefits Sharing of storage –Access to common data –Professional back-up facilities –Centralized software (& data) maintenance Sharing of processing power –Unloading of central servers –Supporting local clients for exceptional needs Sharing of expensive peripherals

31. Postacademic Interuniversity Course in Information Technology – Module C1p31 Terminal Emulation = sub-minimal Client-server system The personal workstations are used –as stand alone computers –as terminals connected to other computers The user has to mentally switch between widely different user interfaces and operating systems. Transferring data between local and remote applications is far from trivial Terminal emulation is very user unfriendly !!!

32. Postacademic Interuniversity Course in Information Technology – Module C1p32 Virtual Mainframe = true Client-Server system The users interface of all applications runs on the personal workstations. For some applications, the workstation requests help from specialized servers. The user remains unaware of such requests. Servers can be optimized for specific tasks Virtual Mainframes can be –Very user friendly –cost effective

33. Postacademic Interuniversity Course in Information Technology – Module C1p33 Contents The 19th century telecommunications –Telegraph - Telephone –Digital vs. analog communications The voice networks & the data networks The electronics revolution (1960-1980) –Digital sound –Mainframe computers with remote access –The first unification : ISDN –Local area networks –Wide area and local area networks integration The Internet –The research project –The universal computer communications medium –The successful unification ?

34. Postacademic Interuniversity Course in Information Technology – Module C1p34 70’s: Open Networks CCITT/ISO start standardization work for Open Systems Interconnection ARPA finances Research on open Network Technology: a Research WAN, ARPANET research on LAN interconnections Combination of the two ARPA efforts resulted in the INTERNET

35. Postacademic Interuniversity Course in Information Technology – Module C1p35 The Early ARPANET (1976) Hawaii London Satellite link 56 Kbps terrestrial link

36. Postacademic Interuniversity Course in Information Technology – Module C1p36 The Results: TCP/IP + Set of Application Protocols –Set of communication “standards” allowing interoperability of almost all brands of computers. –Applicable to Local Area Networks Wide Area Networks Interconnection of LAN’s through WAN’s The INTERNET –Communication facility for the Research Community –Financed by US government

37. Postacademic Interuniversity Course in Information Technology – Module C1p37 The success of TCP/IP To connect a computer to the ARPANET, TCP/IP is required ! Many different computers in use in Universities and research centers. TCP/IP becomes THE networking software available on ALL machines. Many stand-alone networks using TCP/IP appear due to the wide availability of TCP/IP and the many applications available for it.

38. Postacademic Interuniversity Course in Information Technology – Module C1p38 The success ARPANET –Universities where TCP/IP was developed start using the ARPANET backbone as a general purpose communication network. Other universities and research centers also want to get connected: with the help of the NSF, ARPANET becomes the North American Research Network. FREE access but “Acceptable Use Policy” imposed by ARPA on all users. Exponential growth of number of users Enormous help for US researchers.

39. Postacademic Interuniversity Course in Information Technology – Module C1p39 Major Internet Changes 1989-1992 DARPA is no longer the major funds provider. Apparition of the.COM domain Backbone operated by private companies and paid by the US-NSF and the connected networks. “Acceptable Use Policy” no longer required on the backbone, even if many of the connected networks still have one. Commercial “Internet Service Providers” build private networks to connect their subscribers to the Internet. The Internet has become a set of independently financed, cooperating regional networks.

40. Postacademic Interuniversity Course in Information Technology – Module C1p40 Internet Cost Structure RARE Backbone infrastructure and neutral interconnects Paid by interconnected networks, proportional to their access bandwidth. Cost of direct interconnects shared by partners. Not ACTUAL but POTENTIAL traffic is charged. USA Surfnet Planet Uunet NL Belnet eunet Skynet Planet Uunet BE

41. Postacademic Interuniversity Course in Information Technology – Module C1p41 Firewalls = Intranet = Internet = Secure Intranet = Firewall

42. Postacademic Interuniversity Course in Information Technology – Module C1p42 The Internet Integration of voice & data services ??? Internet has become almost as ubiquitous as the traditional telephone network. Internet cost structure based upon potential usage capabilities rather than actual usage. Larger and larger parts of the Internet have multi-media capabilities. Talking over the Internet becomes a realistic low-cost alternative to the traditional telephone service. Can the present Internet survive a victory over the traditional telephone operators ??? Will telephone operators themselves move their traffic to the Internet ???

43. Postacademic Interuniversity Course in Information Technology – Module C1p43 The Multi-media challenge Voice & ImagesData Correctness:Non-essentialEssential Delay:Small & Stable Unimportant The notion of “Quality of Service” Conclusion: Data and multi-media traffic have totally different requirements Mixing them on a single network is technically and economically challenging

44. Postacademic Interuniversity Course in Information Technology – Module C1p44 Introduced concepts Digital vs. Analog communications –Analog signals degraded by noise –Digital signals can be restored to their original shape –Different requirements for data and multi-media Data transmission and Signaling –Signaling = management of the data transmission Client-server systems The Internet –A set of protocols –A set of interconnected networks Intranet –Part of the Internet behind a firewall.