1. Computer Network Lab. 1 2 장 데이터 통신 기본 개념 2.1 회선 구성 (Line configuration) 2.2 토플로지 (Topology) 2.3 전송 모드 (Transmission mode) 2.4 네트워크 분류 (Categories of Networks) 2.5 인터네트워크 (Internetworks) 2.6 요약

2. Computer Network Lab. 2 기본 개념 n Fives general concepts provide the basis for the relationship between the communicating devices. l Line configuration l Topology l Transmission mode l Categories of Networks l Internetworks

3. Computer Network Lab. 3 2.1 회선 구성 ~ refer to the way two or more communication devices attach to a link. ~ defines the attachment of communication devices to a link Line configuration Multipiont Point-to-point

4. Computer Network Lab. 4 회선 구성 (cont’d) n 점 - 대 - 점 (Point-to-point) ~ provides a dedicated link between two devices. n 멀티포인트 (Multipoint) ~ is one in which more than two specific devices share a single link

5. Computer Network Lab. 5 회선 구성 (cont’d) n 점 - 대 - 점 회선 구성 Link

6. Computer Network Lab. 6 회선 구성 (cont’d) n 점 - 대 - 점 회선 구성 Link

7. Computer Network Lab. 7 회선 구성 (cont’d) n 점 - 대 - 점 회선 구성

8. Computer Network Lab. 8 회선 구성 (cont’d) Link n 다중 포인트 회선 구성

9. Computer Network Lab. 9 2.2 토플로지 (Topology) ~ refer to the way a network is laid out, either physically or logically ~ defines the physical or logical arrangement of link in a network n A consideration when choosing a topology is the relative status of the devices to be linked. ¬ peer-to-peer : the devices share the link equally(ring, mesh) ­ primary-secondary : one device controls traffic and the others must transmit through it

10. Computer Network Lab. 10 토플로지 분류 (Categories of topology) Topology Mesh Star Tree Bus Ring

11. Computer Network Lab. 11 Mesh n every device has a dedicated point-to-point link to every other device. n A fully connected mesh network therefore has n(n- 1)/2 physical channels to link n devices.

12. Computer Network Lab. 12 Mesh(cont’d) n Advantages l the use of dedicated links guarantees that each connection can carry its data load. l a mesh topology is robust. l Privacy and security. l Point-to-point links make fault identification and fault isolation easy.

13. Computer Network Lab. 13 Mesh(cont’d) n Mesh topology # of full-duplex links of the fully-connected one hop network with N nodes N(N-1)/2. eg. N=10, # of links = 45 N = 100, # of links 5000.

14. Computer Network Lab. 14 Mesh(cont’d) n Disadvantage ~ are related to the amount of cabling and the number of I/O ports ¬ because every device must be connected to every other device, installation and reconfiguration are difficult ­ the sheer bulk of the wiring can be greater than the available space(in walls, ceiling, or floors) can accommodate ® the hardware required to connect each link(I/O port and cable) can be prohibitively expensive

15. Computer Network Lab. 15 Star n each device has a dedicate point-to-point link only to a central controller, usually called a hub.

16. Computer Network Lab. 16 Star(Cont’d) n Star topology

17. Computer Network Lab. 17 Star(cont’d) n Advantage l each device needs only one link and one I/O port to connect it to any number of others(easy to install and reconfigure) l robustness ä if one link fails, only that link is affected

18. Computer Network Lab. 18 Tree n is a variation of a star l simple shared hub(wiring concentrator) äactive hub(central hub) ~ contains a repeater, which is a hardware device that generates the received bit patterns before sending them out äpassive hub ~ provides a simple physical connection between the attached devices l switching hub ~ provides a switching function l intelligent Hub ~network management function

19. Computer Network Lab. 19 Tree(cont’d) n Tree topology Hub

20. Computer Network Lab. 20 Tree(cont’d) n Advantage & Disadvantage l are generally the same as those of a star

21. Computer Network Lab. 21 Bus n is multipoint. One long cable acts as a backbone to link all the device in the network n Nodes are connected to the bus cable by drop lines and taps l drop line ~ is a connection running between the device and the main cable l tap ~ is a connector either splices into the main cable or punctures the sheathing of a cable to create a contact with the metallic core

22. Computer Network Lab. 22 Bus(cont’d) n Bus topology

23. Computer Network Lab. 23 Bus(cont’d) n Advantage ~ include ease of installation n Disadvantage ~ include difficult reconfiguration and fault isolation

24. Computer Network Lab. 24 Ring n each device has a dedicated point-to-point line configuration only with the two devices on either side of it n Advantage ~ is relatively easy to install and reconfigure ~ fault isolation is simplified n Disadvantage l unidirectional traffic äbreak in the ring can disable the entire network(dual ring)

25. Computer Network Lab. 25 Ring(cont’d) n Ring topology

26. Computer Network Lab. 26 Hybrid topology

27. Computer Network Lab. 27 2.3 전송모드 (Transmission mode) ~ is used to define the direction of signal flow between two link devices n 단방향 (Simplex) l is unidirectional, as on a one-way street(keyboard, monitor) n 반이중 (Half-Duplex) l each station can both transmit and receive, but not at the same time n 전이중 (Full-Duplex) l both stations can transmit and receive simultaneously

28. Computer Network Lab. 28 전송모드 (cont’d) Transmission modes Half-duplex Simplex Full-duplex

29. Computer Network Lab. 29 전송모드 (cont’d) Mainframe Monitor Direction of data n 단방향 (Simplex)

30. Computer Network Lab. 30 전송모드 (cont’d) Workstation Direction of data at time 1 Direction of data at time 2 n 반이중 (Half-Duplex)

31. Computer Network Lab. 31 전송모드 (Full-Duplex) Workstation Direction of data at all the time n 전이중 (Full-Duplex)

32. Computer Network Lab. 32 2.4 네트워크 분류 (categories of Networks) n three primary categories l LAN l MAN l WAN n size, ownership, distance it cover, physical architecture

33. Computer Network Lab. 33 네트워크 분류 (cont’d) Metropolitan area network (MAN) Metropolitan area network (MAN) Local area networks (LAN) Local area networks (LAN) Wide area network (WAN) Wide area network (WAN) Network

34. Computer Network Lab. 34 n LAN(Local Area Networks) ~ is usually privately owned and links the devices in a single office, building or campus 네트워크 분류 (cont’d)

35. Computer Network Lab. 35 네트워크 분류 (cont’d) n Single building LAN

36. Computer Network Lab. 36 네트워크 분류 (cont’d) Backbone n Multiple building LAN

37. Computer Network Lab. 37 네트워크 분류 (cont’d) n MAN(Metropolitan Area Networks) ~ is designed to extend over an entire city

38. Computer Network Lab. 38 네트워크 분류 (cont’d) Public city network n MAN

39. Computer Network Lab. 39 네트워크 분류 (cont’d) n WAN(Wide Area networks) ~ provides long-distance transmission of data, voice, image, and video information over large geographical areas that may comprise a country, a continent, or even the whole world

40. Computer Network Lab. 40 네트워크 분류 (cont’d) n WAN

41. Computer Network Lab. 41 2.5 인터네트워크 (Internetworks) ~ is an interconnection of networks by the use of internetworking device(router and gateway) n cf l internet: an interconnection of networks l Internet: a specific worldwide network

42. Computer Network Lab. 42 Internetworks(internet)

43. Computer Network Lab. 43 2.6 요약 n 숙제 l Exercise 3,5,7