Technologies and Applications of Computer Networks 林永松 台灣大學資訊管理學系 yslin@im.ntu.edu.tw (02)3366-1191

Syllabus Textbook: Course objectives “Computer Networks”, 4rd Ed., by Andrew S. Tanenbaum, carried by 新月 Course objectives to introduce the importance of computer networks to discuss hardware, software and architecture issues for computer networks to discuss essential layers that constitute a protocol stack to discuss a number of applications over networks to introduce methodology for network planning & management to train executive professionals who need to know computer networks

Syllabus (cont’d) Course outline (tentative) introduction uses of computer networks network hardware network software reference models network standardization

Syllabus (cont’d) Course outline (cont’d) physical layer the theoretical basis for data communication transmission media wireless transmission the telephone system data link layer data link layer design issues error detection and correction elementary data link protocols sliding window protocols

Syllabus (cont’d) Course outline (cont’d) medium access sublayer the channel allocation problem multiple access protocols IEEE standard 802 for LANs and MANs

Syllabus (cont’d) Course outline (cont’d) network layer network layer design issues routing algorithms congestion control algorithms internetworking the network layer in the Internet transport layer the transport service elements of transport protocols the Internet transport protocols (TCP and UDP)

Syllabus (cont’d) Course outline (cont’d) application layer network security SNMP - simple network management protocol Content-based information retrieval/filtering multimedia network planning and capacity management network planning network capacity management other materials

Introduction Uses of computer networks resource sharing information retrieval information distribution communication reliability/survivability/availability gradual growth performance to cost ratio

Introduction (cont’d) Network hardware network classification broadcasting, multicasting and unicasting (point-to-point) scale of interconnected processors Fig. 1-2 (p. 8)

Introduction (cont’d) Network hardware (cont’d) local area networks (LANs) size transmission technology medium access protocols topology Fig. 1-3 (p. 9)

Introduction (cont’d) Network hardware (cont’d) metropolitan area networks (MANs) characteristics DQDB (distributed queue dual bus) Fig 1-4 (p. 11)

Introduction (cont’d) Network hardware (cont’d) wide area networks (WANs) size host and subnet Fig. 1-5 (p.12)

Introduction (cont’d) Network hardware (cont’d) wide area networks (cont’d) circuit switching versus packet switching topology Fig. 1-6 (p. 13)

Introduction (cont’d) Network hardware (cont’d) wireless networks need for mobile and/or wireless communication Fig. 1-7 (p.14)

Introduction (cont’d) Network hardware (cont’d) wireless networks (cont’d) e.g. PDAs (personal data assistants) and CDPD (cellular digital packet data) different combinations of wired and wireless networking Fig. 1-8 (p. 15)

Introduction (cont’d) Network hardware (cont’d) internetworks internet: a collection of interconnected networks, e.g. a collection of LANs connected by a WAN Internet subnet: a collection of routers and communication lines owned by the network operator network: the combination of a subnet and its hosts

Introduction (cont’d) Network software protocol hierarchies Fig. 1-9 (p. 17)

Introduction (cont’d) Network software (cont’d) example information flow Fig. 1-11 (p.20)

Introduction (cont’d) Network software (cont’d) design issues for the layers identification of senders and receivers simplex, half-duplex and full-duplex error control sequencing flow control message length (SAR and multiplexing) multiplexing and demultiplexing routing

Introduction (cont’d) Network software (cont’d) interfaces and services Fig. 1-12 (p.23)

Introduction (cont’d) Network software (cont’d) connection-oriented and connectionless services Fig. 1-13 (p.25)

Introduction (cont’d) Network software (cont’d) service primitives Fig. 1-14 (p. 25)

Introduction (cont’d) Network software (cont’d) a simple connection-oriented service example CONNECT.request CONNECT.indication CONNECT.response CONNECT.confirm DATA.request DATA.indication DISCONNECT.request DISCONNECT.indication

Introduction (cont’d) Reference models OSI (Open Systems Interconnection) reference model principles of layering different level of abstraction well defined functions defining internationally standardized protocols minimal information flow across the interfaces appropriate number of layers

Introduction (cont’d) Reference models (cont’d) OSI reference model (cont’d) Fig. 1-16 (p.29)

Introduction (cont’d) Reference models (cont’d) OSI reference model (cont’d) Fig. 1-17 (p.34)

Introduction (cont’d) Reference models (cont’d) TCP/IP reference model Fig. 1-18 (p.36)

Introduction (cont’d) Reference models (cont’d) TCP/IP reference model (cont’d) Fig. 1-19 (p.37)

Introduction (cont’d) The Internet a collection of interconnected TCP/IP networks to be on the Internet, a machine must run the TCP/IP protocol stack have an IP address be able to send IP packets to all the other machines on the Internet applications: email, news, telnet, ftp, SNMP, WWW millions of hosts and tens of millions of users

Introduction (cont’d) The Internet (cont’d) standard organizations IAB (Internet Activities Board) by DoD in 1983, later changed to Internet Architecture Board, using RFCs (Request For Comments) for communication IRTF (Internet Research Task Force) and IETF (Internet Engineering Task Force) under IAB in 1989 Internet Society in 1992 from a proposed standard to a draft standard and finally to an Internet standard