Basic Concepts

1. Basic Concepts Prof. Choong Seon HONG

2. Basic Concepts • Five general concepts provide the basis for the relationship between the communicating devices. • Line configuration • Topology • Transmission mode • Categories of Networks • Internetworks

3. 2.1 회선구성 (Line configuration) ~ refers to the way two or more communication devices attach to a link ~ defines the attachment of communication devices to a link Line configuration Point-to-point Multipiont

4. Line configuration (cont’d) • 점-대-점(Point-to-point) ~ provides a dedicated link between two devices. • 다중 점(Multipoint) : multidrop ~ is configuration in which more than two specific devices share a single link

5. Link Line configuration (cont’d) • 점-대-점 회선 구성

6. Link Line configuration (cont’d) • 점-대-점 회선 구성

7. Line configuration (cont’d) • 점-대-점 회선 구성

8. Line configuration (cont’d) • 다중 점 회선 구성

9. 접속형태(Topology) ~ refers to the way a network is laid out, either physically or logically ~ defines the physical or logical arrangement of link in a network • 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 (star, tree)

10. 접속형태 분류(Categories of topology) Topology Mesh Star Bus Ring Tree

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

12. 그물형(cont’d) • Mesh topology

13. Mesh (cont’d) • Advantages • The use of dedicated links guarantees that each connection can carry its data load. • Mesh topology is robust. • Privacy and security. • Point-to-point links make fault identification and fault isolation easy.

14. 그물형 (cont’d) • Disadvantages ~ 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. 스타형 (Star : 성형) • Each device has a dedicated point-to-point link only to a central controller, usually called a hub

16. Star (cont’d) • Star topology

17. Star (cont’d) • Advantage • Each device needs only one link and one I/O port to connect it to any number of others (easy to install and reconfigure) • Robustness • if one link fails, only that link is affected

18. 트리형 (Tree) • is a variation of a star • active hub(central hub) ~ contains a repeater, which is a hardware device that generates the received bit patterns before sending them out • passive hub ~ provides a simple physical connection between the attached devices

19. Tree (cont’d) • Tree topology

20. Tree (cont’d) • Advantage & Disadvantage • are generally the same as those of a star

21. 버스형 (Bus) • is multipoint. One long cable acts as a backbone to link all the devices in the network • Nodes are connected to the bus cable by drop lines and taps • drop line ~ is a connection running between the device and the main cable • 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. Bus (cont’d) • Bus topology

23. Bus (cont’d) • Advantages ~ include ease of installation • Disadvantages ~ include difficult reconfiguration and fault isolation

24. 링형 (Ring) • Each device has a dedicated point-to-point line configuration only with the two devices on either side of it • Advantage ~ is relatively easy to install and reconfigure ~ fault isolation is simplified • Disadvantage • unidirectional traffic • break in the ring can disable the entire network --> needs dual ring

25. Ring (cont’d) • Ring topology

26. 혼합형(Hybrid topology)

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

28. Transmission Mode (cont’d) Transmission modes Simplex Half-duplex Full-duplex

29. Transmission Mode (cont’d) • 단방향 (Simplex)

30. Transmission Mode (cont’d) • 반이중(Half-Duplex)

31. Transmission Mode (cont’d) • 전이중(Full-Duplex)

32. 2.4 네트워크 분류 (Categories of Networks) • three primary categories • 근거리 통신망 (LAN) • 도시 통신망 (MAN) • 광역 통신망 (WAN) • size, ownership, distance it cover, physical architecture

33. Categories of Networks (cont’d) Network Wide area network (WAN) Local area networks (LAN) Metropolitan area network (MAN)

34. Categories of Networks (cont’d) • LAN(Local Area Networks) ~ is usually privately owned and links the devices in a single office, building or campus

35. Categories of Networks (cont’d)

36. Categories of Networks (cont’d) • MAN(Metropolitan Area Networks) ~ is designed to extend over an entire city

37. Categories of Networks (cont’d) • 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

38. Categories of Networks (cont’d) • WAN

39. 2.5 네트워크간 네트워크 (Internetworks) ~ is an interconnection of networks by the use of internetworking device(router and gateway) • cf. • internet: an interconnection of networks • Internet: a specific worldwide network

40. Internetworks (cont’d) • Internetwork (internet)