Networking

1
Networking
2
Telecommunication

• ????????????????????????????????????????
  Electronic ?????????????????????????
• ????????????????????? (voice) ????????????????????
  ????? digital ???

3
Information Superhighway

• ???????????????????????? digital ???????????
  ?????????????????????????????? ???????????????????
  ?????????????????????

4
????????????????? Telecommunications

• Computers ???????????????????
• Terminals ???? input/output devices
  ?????????????????
• Communications channels ???????????????
  ???????????
• Communications processors ???????????????????????
  ?????????????????? ???? modems, multiplexers
• Communication software

5
Protocols

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

6
?????????????

• Analog signal ????????????????????????
• Digital signal ???????????????????????????

7
Modem

• MOdulation/DEModulation ??????????????????????????
  ?? digital ??????? analog ??? analog ???????
  digital
• ??????????????????????????????????????????????????
  ?????????

8
Types of Communications Channels

• Wire
• Twisted Pair
• Coaxial Cable
• Fiber Optics
• Wireless
• Microwave
• Satellite

9
Twisted Pair

• ????????????????????? Twisted Pair ??? Unshielded
  Twisted Pair
• ?????????????????????????????????????????????
• ??????? ??????? ???????????
• ??????? ?????????????????? ?????????????????
• ?????????????????????????????????????????????
  (Lan)

10
Coaxial Cable

• ?????????????????????????????????????
• ??????? ???????????????????????
  ????????????????????????? twisted pair
• ??????? ?????????????????????? twisted pair
• ?????????????????????????????????????????????????
  ????????????????????

11
Fiber Optics

• ?????????????????????
• ???????????????????????????
• ??????? ??????????????????????????????????
  ?????????? ?????
• ??????? ??????? ???????????? ???????
• ??????????????????? backbone ????????????????

12
Microwave

• ????????????????????????????????????????????
  ??????? ???????????????????????
• ????? microwave ???????????????
  ????????????????????????????????????????????
  40-50 ????????

13
Satellites

• ????????????????????????????????????????????
  ???????????
• ?????????????????????????????? 35,200 ????????
  (22,000????) ??????
• ??????????????????????????????????????????????????
  ??????

14
Transmission Speed(??????????????????????)

• ???????????????????????????????????? bits per
  second (bps) ???????????? baud rate
• ???? ????????
• Microwave 100 MBPS
• Satellite 100 MBPS
• Twisted wire 150 MBPS
• Coaxial cable 200 MBPS
• Fiber-optic cable 10 GBPS

15
????????????????? communication
channel?????????????

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

16
??????? - ????????

• ??????? ???????? (?????????)
• ??????????????? 10 MB
• ???????????? 100 MB
• ???????????????? gt 100 MB

17
Twisted wire VS Fiber-Optic

• ????????????????????? Twisted wire ???
  Fiber-Optic ?????? Lan ?????????????????? fiber
  optic ??????????????????????????????????
  ??????????
• ??????????????????? ?????????????????????????????
• ?????????????????????????????
• ????????????????????

18
Bandwidth

• ???????????????? communication channel
  ??????????????????????? ?????? ??? ??????

19
Bandwidth

• ???????? voice-grade channel ?????????????????????
  ???????????? 30 - 3400 hertz (Hz) ??????????????
  bandwidth ??????? 3100 hertz (Hz)

3400 Hz
30 Hz
20
Bandwidth

• ?????????????? commnunication ?????
  ???????????????? ?????????????????
• ??? communication channel ?? bandwidth
  ??????????????????????????????????????????????

500 KHz
VIDEO
VOICE
DATA
300 Hz
21
Baseband and Broadband

• Baseband (narrowband) bandwidth
  ????????????????????????????????????????????
• Broadband (wideband) ????? bandwidth
  ?????????????????????????????????

Broadband
Baseband
22
Network Topologies??????????????????

• The Star network
• The Ring Network
• The Bus Network

23
Network Topologies
24
?????????????? Network

• ???????????? Topology ??????????? ?
  ??????????????????????????????????????????????????
  ???

25
The Star Topology

• ???????? Host Computer ????????????????????????
• ????????????? Mainframe ?????????? Centralized
  Processing
• ?????????????????????????????????????????????????
  (vulnerability) ??????????????????????????????????
  ????? host computer

26
The Ring Topology

• ????????????????????????????????????? (closed
  loop)
• ?????????????????????????? token ?????????? token
  ?????????????? loop
• ?????????????????????? token ?????????????????????
  ?????????????
• ????????????????????????? token
  ???????????????????????? ????????? token ??????

27
The Ring Topology

• ???????????? ????????? ring ??????????????????????
  ???????? ????????????????????????
  ??????????????????????????????????

28
The Ring Topology

• ?????????????????????????????????????? HUB ????
  Media Access Unit (MAU) ??????????????????????????
  ??????? ring ???????????

MAU
29
The Bus Topology

• ??????????????????????????????? ???????????????
  ?????????????????????????? ? ???????????????
  ?????????????????????????????????????
• ????????????????? Bus ??????????????????????????
  Lan (Local Area Network)

30
The Bus Topology

• ????????? BUS ???????????????????????????????????
  BUS WITH SPUR

31
The Bus Topology

• ???????????? ????????? ring ??????????????????????
  ???????? ????????????????????????
  ??????????????????????????????

32
The Bus Topology

• ?????????????????????????????????????? HUB ????
  Media Access Unit (MAU) ??????????????????????????
  ??????? BUS ???????????

MAU
33
???????????????? Hub ?????? Bus Topology

• ????????????????????????????????????????
• ?????????????????????????????????
• ?????????????????????????????????????? port ???
  Hub

34
?????????????????? BUS Topology

• ??????????????? ??????????????????????????????????
  ????
• ???????????????????????????????????
  ???????????????????????
• ?????????????????????????????????????????????
  ????????????????????????????????????
• ????????????????????????????????????????
• ??????????????????????????????????????????????????
  ????
• Protocol ????????????? Carrier Sense Multiple
  Access / Collision Detection (CSMA/CD)

35
????????????????????????
????????????
?????
???????
?????????
???
RCU
RCU
????????????
?????
?????
???
??????
36
????????

• ????????????????????????????? Bus Topology
  ??????????????????????????????????????????????????
  ????? 1,000 ??????? ??????????????????????????????
  ???????? ?????????????????????????????????????????