????(computer networks)

1

• ????(computer networks)

2
????(Communications Protocols)

• ???(Point-to-Point)???
• ???(End-to-End)???

3
??????
4
OSI?????

• 1977?,??????(Internetational Standard
  Organization, ??ISO)?????OSI???????????1984?,???OS
  I(Open System Interconnection reference model ,
  ?????????? )??????,??????????????????????
• OSI????????????(ISO)????????????(CCITT)??????(?73)
  ?????????????????????(American National
  Standards Institute, ??ANSI),??????????????????

5
ISO/OSI????
6
OSI??

• ??
• ???????????,????????
• ?????????,?????????????????
• ?????????????????
• ??????,???????????????????????
• ???????????????????

7
????

• OSI???????????????????????

8
????
?????,?????
9
ISO/OSI??

• ??? (Physical layer)
• ???(Data link layer)
• ???(Network Layer)
• ???(Transport Layer)
• ???(Session Layer)
• ???(Presentation Layer)
• ???(Application Layer)

10
ISO/OSI??

• ??? (Physical layer)
• ?????????????????????
• ?????(Data link layer)
• ????????????????????,??????????????
• ???(Network Layer)
• ???????????????(Routing)??,?????????????????

11
ISO/OSI??

• ???(Transport Layer)
• ????????????,?????????????????????????????????????
  ????????????????????????????????????
• ???(Session Layer) (???)
• ????????????????,?????????,????????????????,??????
  ??????OSI??????????,??????????,?????????????

12
ISO/OSI??

• ???(Presentation Layer) (???)
• ??????????????????,????????????????????,??????????
  ???????,?tab?????????
• ???(Application Layer)
• ????????????????????,??????????????????,??????????
  ????????????

13
OSI?????????????????
?? ???????
??? Message(??)
??? Data(??)
??? ?
??? Segement(??)
??? Datagram(???)?Packet(??)
????? Frame(???)
??? Bit(??)
14
????
15
OSI??

• ???OSI????????

Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
16
OSI??

• ???????????,??????
• ???????????,???????

17
????????????,??????,????????,???????
???? ??? ????
???? Hp ???? ??? ???? Hp ????
Hs Hp ???? ??? Hs Hp ????
Ht Hs Hp ???? ??? Ht Hs Hp ????
Hn Ht Hs Hp ???? ??? Hn Ht Hs Hp ????
Hd Hn Ht Hs Hp ???? Td ????? Hd Hn Ht Hs Hp ???? Td
Hd Hn Ht Hs Hp ???? Td ??? Hd Hn Ht Hs Hp ???? Td
????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits) ????(bits)
18
????????
19
????????(Taxonomy)

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

20
?????

• ????????????????
• ????(Local Area Netware,LAN)
• ????(Metropolitan Area Netware,MAN)
• ????(Wide Area Netware,WAN)

21
??LAN?MAN?WAN

• ???? ( LANLocal Area Network )
• ??????????????????????????????
• ?????????????????
• ???? ( MANMetropolitan Area Network )
• ??????????????????????
• ???? ( WANWide Area Network )
• ??????????????????????
• ?????????????????

22
LAN?MAN?WAN???
????????????????????
23
???????
????
24
????

• ????????????????,???
• CSMA/CD?Carrier-Sence Multiple Access with
  Collision Detection???,???????(Ethernet ,IEEE
  802.3)?????????
• Token Passing?????IEEE 802.4?IEEE 802.5?????????
• Demand Priority??????IEEE802.12(??100VG
  AnyLan)?????????

25
????

• ??? TCP/IP ?????

26
???????

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

27
?????????

• ????
• ?????????, ??, ????.
• ??
• ?????
• ??
• ?????????(????)

28
TCP/IP ??

• ???(Physical layer)
• ?????(Network access layer)
• ?????(Internet layer)
• ???(Transport layer)
• ???(Application layer)

29
TCP/IP Physical Layer

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

30
TCP/IP Network Access Layer

• ?????
• ??????????????????????
• ?????????????
• ????(Circuit switching)
• ????(Packet switching, ?, X.25)
• ????(LAN, ?, Ethernet)
• ??

31
TCP/IP Internet Layer

• ?????
• ????????(Internet Protocol, IP)
• ????????????????(traverse)?????( routing
  functions).
• ???????????.

32
TCP/IP Transport Layer

• ???
• ??????????(Transmission Control Protocol, TCP)
• ?????????
• ???(Completeness)
• ??(Order)

33
TCP/IP Application Layer

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

34
TCP/IP ??

• ????????(Simple mail transfer protocol,SMTP)
• ???????????
• ????(File Transfer Protocol, FTP)
• ???????????????
• ????(TELNET)
• ????????

35
OSI ? TCP/IP ???
36
TCP/IP ?????

• TCP/IP ??? OSI ???????
• ??????????????, ?? TCP/IP????????
• OSI ??????
• ???OSI???, TCP/IP ??????

37
???????

• Communication network ????,??????????????????
• Internet ????, ????/??????????????
• Intranet ????, ??????????????
• ???????????
• ?????????????????

38
??Intranet?Extranet

• Intranet?????????????,????Internet?????,??????,???
  ??????????????
• Extranet??????????Internet??????????,?????????????
  ??

39
Intranet?Extrant?????
Intranet Extranet
??? ???? ?? ????????
??? ??? ??????? ???????
??? ??? ? ??
??? ????TCP/IP??????????? ????TCP/IP??????????? ????TCP/IP???????????
40
??????? (?)

• End System (ES) ????, ?????????????
• Intermediate System (IS) ????, ??????????
• Bridge ???, ?? IS, ?????????????????
• Router ????? IS, ?????????????

41
Router ???

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

42
????? Routers ????

• ????
• ?????????
• ??????
• ???????????(segmentation)
• ??
• ?????????
• ???
• ??????????