IS516 Computer Communication and Networks Lecture 02:

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IS516 ?????????????????????????????????
(Computer Communication and Networks)
Lecture 02 ???????????????????????????
?????????????????
2
???????????????????? (???? Mid-term)
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Topic

• Computer Networks
• Uses of computer networks
• Network taxonomy
• Reference model
• Network Standardization

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Computer Network

• ????????????????????????(Computer Network)
  ??????????????????????????????????????????????????
  ????????? ????????????????????????????????????????
  ???????????????????????? ????????????????????
  ??????????????? ????????????????
  ?????????????????????
• ??????????????????????????????????????????????????
  ??????????????????????????????????????

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IS516 ?????????????????????????????????
Uses of computer networks

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Uses of Computer Networks

• ???????????????????? (Business Applications)
• ??????????????????????? (Home Applications)
• ??????????? (Mobile Users)
• ??????????????? (Social Issues)

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Objectives of Business Applications

• Resource sharing, Information sharing
• Communication medium
• E-commerce B2B
• E-commerce through Internet B2C

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Client-Server Model

• A network with two clients and one server.

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Processes in Client-Server model

• The client-server model involves requests and
  replies.

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Home Network Applications

• ???????????????????????????????? (Access to
  remote information)
• e.g. e-banking, e-shopping, e-library,
  e-newspaper, etc.
• ??????????????????????-???-?????
  (Person-to-person communication)
• e.g. e-mail, instant messaging, chat room, etc.
• ???????????????????? (Interactive entertainment)
• e.g. video on demand
• ???????????????????????? (Electronic commerce)
• e.g. B2C, G2C, C2C, P2P

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Peer-to-Peer system

• In peer-to-peer system there are no fixed
  clients and servers.

????????????????????? peer-to-peer
????????????????????????????????????????
Napster ?????????????????????????? 50
?????? http//www.arip.co.th/2006/news.php?id1034
80 http//www.blognone.com/node/4261
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e-Commerce

• Some forms of e-commerce.

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Mobile Network Users
??????????????? (Wireless network)
??? ???????????????? (mobile computing)
Desktop computers in office
No
May Be
A notebook computer used in a hotel room
May Be
Yes
Networks in older, unwired buildings
Yes
No

• Portable office, PDA for store inventory

Yes
Yes
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Social Issues

• ??????????????????????????????????????????????????
  ??????????????????????????? ?????????????????????
  ??????????????????????????
• ?????????????????????????????? ???????????????????
  ?????????????????????????????????????

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IS516 ?????????????????????????????????
Network taxonomy

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????????????????????????

• ??????????????????????????????? (Transmission
  Technology)
• ????????????? (Broadcast Networks)
• ??? - ??? - ??? (Point-to-Point Networks)
• ???????????????? (Scale)
• ????????????????????? (Local Area Networks)
• ??????????????????? (Metropolitan Area Networks)
• ???????????????? (Wide Area Networks)

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Broadcast Networks

• ?? 1 ?????????????? ??????????????????????????????
  ?????
• ???????????????????????????? packet
  ??????????????????????????????????????
  ?????????????????????????????? packet ????????
• ?????????????????????????? packet
  ??????????????????? ??????????????????????????????
  ??????
• ??? broadcasting ?????????????????????????????????
  ?????????? packet ????????????????????????????????
  ???????????????????
• Multicasting ??????????????????????????
  ????????????????????????????????
• ????????????????????????????

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Point-to-Point Networks

• ??????????????????????????????????????????????
• ??????????????? packet ???????????????????????????
  ??????????????????????????
• packet ???????????????????????????????????????????
  ???? (router) ????????????????????????????????????
  ??? ????????? packet ?????????
• ????????????????????????????
• ???????????????? Unicasting

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??????????????????????????????????????

• Classification of interconnected processors by
  scale.

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????????????????????? (LAN)

• ???????? ???????????????? ?????????????? 2-3 ?.?.
• ??????????????????????????????????????????????????
  ????????????????????
• ?????????????????????????????????????????????
• ?????????????? 10 Mbps ???? 100 Mbps
• ???????????????????????????????????????? 100 ?sec
• ?????????????????????????????????
• ??????????????????? Bus network ??? Ring network

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Bus Network

• Bus network ?????????????????????
  ???????????????????????????????????????
• ???????????????????????????????????????????
  (collision) ??????????????????????????????????????
  ???????????????????????? ???????????????????????
• ??????????????????? IEEE 802.3 (Ethernet)

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Ring Network

• ?????????????? Ring network ??????????????????????
  ?????????????????????????????
• ??????????????????????????????????????????????????
  
• ??????????????????? IEEE 802.5 (IBM Token Ring)
• ???????????????????????????? 4 ??? 16 Mpbs
  ???????? FDDI

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Local Area Networks

• Two broadcast networks
• (a) Bus
• (b) Ring

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Local Area Network
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??????????????????? (MAN)

• ??????????????????????????????????????????????????
  ????????
• ????????????????????????????????????-?????????????
  ?????????????? ??????????? cable TV ????
• ???????????????????? 1 ???? 2 ????
  ???????????????????????????????????? (switching
  elements)
• ??????????????????? IEEE 802.16

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Metropolitan Area Networks

• A metropolitan area network based on cable TV.

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Metropolitan Area Network
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???????????????? (WAN)

• WAN (Wide Area Networks) ?????????????????????????
  ?????????????? ???????????????????? LAN ??? MAN
  ??????????????????????????????????????????????????
  ?? ??????????????????????????????????????????
  ????????????????????????????? ????????
  ??????????? ???? Internet ?????????????????????
  WAN ??????????? ??????????????????????????????????
  ?????????????????? ??????????????? WAN
  ?????????????? ???????? Enterprise Network

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???????????????? (WAN)

• ???????????????????????????????????????
• ???????????????????????????????????????? host
  computer ?????????????????????????????????????????
  ????????????????? host ???????????????????????????
  ?????????????????????????-???????????????? host
  ?????
• ??????????????????? WAN ?????????????????????? 2
  ???????? ?????????? (transmission line) ???
  ?????????????????????? (switching element)
• ?????????????????????????? ???? circuit, channel,
  trunk
• ??????????????????????????????????? ?????? packet
  switching, nodes, intermediate system, data
  switching exchanges, router

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Wide Area Networks

• Relation between hosts on LANs and the subnet.

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Packet Switching network

• A stream of packets from sender to receiver.

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Wide Area Network
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Internetwork (Internet)
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(No Transcript)
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IS516 ?????????????????????????????????
Reference model

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???????????????????

• ????????? 2 ???????? ????????????????
• TCP/IP ?????????????????????????
  ??????????????????????????
• OSI ?????????????????????? ??????????????????????
  ??????????????????????????????????????????????????
  ????????????????

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Reference Model of Open Systems Interconnection
(OSI)

• ???????? International Standard Organization
  (ISO) ????????????????????????????????????????????
  ??????????????????????????????????????????????????
  7 ????
• ??????????????????????????????????????????????????
  ?????????(open system) ???????????

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?????????????????????????  OSI

• ???? ?.?.1977  ?????? ISO  (International
  Organization for Standard)  ??????????????????????
  ????????????  ??????????????????????????????? 
  ???????????????????????????? ??????? ?.?.1983 
  ?????? ISO  ??????????????????????????????????????
  ????????????????????? "?????? OSI"   (Open
  Systems Interconnection Model) 
  ??????????????????????????????????????????????????
  ???? ????? "O"  ???? " Open" ?????????
  ??????????????????????????????????????????????? 
  "????" ???????? ??????????????????????????????????
  ?????????????  OSI ???????????????????????????????
  ????????????

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????????????????????? (Layers)

• ??????????????????????????????????????????????????
  ?????
• ??????????????????????????????????????????????????
  ??
• ??????????????????????????????????????????????????
  ????????????????????????????????????????????????
• ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ????????????????????????????????
• ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ????????????

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ISOs OSI (Open Systems Interconnection)

• ?????????????????? Application Layer
• ?????????????????? Presentation Layer
• ????????????? Session Layer
• ????????????????? Transport Layer
• ????????????????? Network Layer
• ????????????????? Data Link Layer
• ?????????????? Physical Layer

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Reference Models
The OSI reference model.
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?????????????????????????  TCP/IP

• TCP (Transmission Control Protocol / Internet
  Protocol)
• ???????????????? 1969 ?????????????????????
  Defense Advanced Research Projects Agency (DARPA)
  ??????????????????????????? Packet Switching
  ????????????????????????????????? ARPANET
  ?????????????????????????? Internet ?????????????
  
• ??????????????????????????????????????????????????
  ???????????

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5 ???????????????????? TCP/IP

• Application Layer
• Transport Layer
• Internet Layer
• Network Access Layer
• Physical Layer

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The OSI vs TCP/IP

• The TCP/IP reference model.

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TCP/IP and the OSI Model
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IS516 ?????????????????????????????????
Network Standardization

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???????????????????????

• ?????????????????????????? 2 ????????? de facto
  ??? de jure
• de facto (???????????????????? ???????????????????
  ) - ??????????
• ??????????????????????????????????????????????????
  ????????????? e.g. IBM PC, Unix
• de jure (???????????????????? ?????????)
  ??????????
• ??????????????????????????????????????????????????
  ????????????????? ????????????????????????????????
  ??????????????????????????????????????????????????
  ??????????????
• ??????????????????????????????????????????????????
  ????????????????

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?????????????????????????????????

• ISO (International Standard Organization)
  ???????????? 1955
• ????????????????????? ??????????????????????
  ??????????????????????????????????????????????????
  ???????? 200 ?? ??????????????????????? 1 ?????
• ????????????????????????????????????????????? 89
  ?????? ???? ANSI, BSI, AFNOR, DIN
• ??????????????????????????????????????????????
  5000 ??????

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Next Lecture
?????????????????????? ??????????????????????????