information technologies -- computer networks 林永松 台灣大學資訊管理學系...
TRANSCRIPT
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Syllabus Textbook:
“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 netwo
rks
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Syllabus (cont’d)
Course outline (tentative) introduction
– uses of computer networks
– network hardware
– network software
– reference models
– network standardization
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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
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Syllabus (cont’d)
Course outline (cont’d) medium access sublayer
– the channel allocation problem
– multiple access protocols
– IEEE standard 802 for LANs and MANs
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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)
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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
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Introduction
Uses of computer networks resource sharing information retrieval information distribution communication reliability/survivability/availability gradual growth performance to cost ratio
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Introduction (cont’d)
Network hardware network classification
– broadcasting, multicasting and unicasting (point-to-point)
– scale of interconnected processors
Fig. 1-2 (p. 8)
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Introduction (cont’d)
Network hardware (cont’d) local area networks (LANs)
– size
– transmission technology
– medium access protocols
– topology
Fig. 1-3 (p. 9)
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Introduction (cont’d)
Network hardware (cont’d) metropolitan area networks (MANs)
– characteristics
– DQDB (distributed queue dual bus)
Fig 1-4 (p. 11)
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Introduction (cont’d)
Network hardware (cont’d) wide area networks (WANs)
– size
– host and subnet
Fig. 1-5 (p.12)
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Introduction (cont’d) Network hardware (cont’d)
wide area networks (cont’d)– circuit switching versus packet switching
– topology
Fig. 1-6 (p. 13)
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Introduction (cont’d)
Network hardware (cont’d) wireless networks
– need for mobile and/or wireless communication
Fig. 1-7 (p.14)
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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)
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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
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Introduction (cont’d) Network software
protocol hierarchies
Fig. 1-9 (p. 17)
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Introduction (cont’d) Network software (cont’d)
example information flow
Fig. 1-11 (p.20)
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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
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Introduction (cont’d) Network software (cont’d)
interfaces and services
Fig. 1-12 (p.23)
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Introduction (cont’d) Network software (cont’d)
connection-oriented and connectionless services
Fig. 1-13 (p.25)
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Introduction (cont’d)
Network software (cont’d) service primitives
Fig. 1-14 (p. 25)
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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
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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
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Introduction (cont’d) Reference models (cont’d)
OSI reference model (cont’d)
Fig. 1-16 (p.29)
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Introduction (cont’d) Reference models (cont’d)
OSI reference model (cont’d)
Fig. 1-17 (p.34)
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Introduction (cont’d) Reference models (cont’d)
TCP/IP reference model
Fig. 1-18 (p.36)
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Introduction (cont’d)
Reference models (cont’d) TCP/IP reference model (cont’d)
Fig. 1-19 (p.37)
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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
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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