Transcript Document

Information Technologies -Computer Networks
林永松
台灣大學資訊管理學系
[email protected]
(02)3366-1191
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
networks
1-2
Syllabus (cont’d)

Course outline (tentative)
 introduction
– uses of computer networks
– network hardware
– network software
– reference models
– network standardization
1-3
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
1-4
Syllabus (cont’d)

Course outline (cont’d)
 medium
access sublayer
– the channel allocation problem
– multiple access protocols
– IEEE standard 802 for LANs and MANs
1-5
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)
1-6
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
1-7
Introduction

Uses of computer networks
 resource
sharing
 information retrieval
 information distribution
 communication
 reliability/survivability/availability
 gradual growth
 performance to cost ratio
1-8
Introduction (cont’d)

Network hardware
 network
classification
– broadcasting, multicasting and unicasting (point-to-point)
– scale of interconnected processors
Fig. 1-2 (p. 8)
1-9
Introduction (cont’d)

Network hardware (cont’d)
 local
area networks (LANs)
– size
– transmission technology
– medium access protocols
– topology
Fig. 1-3 (p. 9)
1-10
Introduction (cont’d)

Network hardware (cont’d)
 metropolitan
area networks (MANs)
– characteristics
– DQDB (distributed queue dual bus)
Fig 1-4 (p. 11)
1-11
Introduction (cont’d)

Network hardware (cont’d)
 wide
area networks (WANs)
– size
– host and subnet
Fig. 1-5 (p.12)
1-12
Introduction (cont’d)

Network hardware (cont’d)
 wide
area networks (cont’d)
– circuit switching versus packet switching
– topology
Fig. 1-6 (p. 13)
1-13
Introduction (cont’d)

Network hardware (cont’d)
 wireless
networks
– need for mobile and/or wireless communication
Fig. 1-7 (p.14)
1-14
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)
1-15
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
1-16
Introduction (cont’d)

Network software
 protocol
hierarchies
Fig. 1-9 (p. 17)
1-17
Introduction (cont’d)

Network software (cont’d)
 example
information flow
Fig. 1-11 (p.20)
1-18
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
1-19
Introduction (cont’d)

Network software (cont’d)
 interfaces
and services
Fig. 1-12 (p.23)
1-20
Introduction (cont’d)

Network software (cont’d)
 connection-oriented and
connectionless services
Fig. 1-13 (p.25)
1-21
Introduction (cont’d)

Network software (cont’d)
 service
primitives
Fig. 1-14 (p. 25)
1-22
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
1-23
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
1-24
Introduction (cont’d)

Reference models (cont’d)
 OSI
reference model (cont’d)
Fig. 1-16 (p.29)
1-25
Introduction (cont’d)

Reference models (cont’d)
 OSI
reference model (cont’d)
Fig. 1-17 (p.34)
1-26
Introduction (cont’d)

Reference models (cont’d)
 TCP/IP reference
model
Fig. 1-18 (p.36)
1-27
Introduction (cont’d)

Reference models (cont’d)
 TCP/IP reference
model (cont’d)
Fig. 1-19 (p.37)
1-28
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
1-29
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
1-30