1. 2장 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. 기본 개념
Fives general concepts provide the basis for the relationship between the communicating devices.
Line configuration
Topology
Transmission mode
Categories of Networks
Internetworks

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
Point-to-point
Multipiont

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

5. 회선 구성(cont’d)
점-대-점 회선 구성
Link

6. 회선 구성(cont’d)
점-대-점 회선 구성
Link

7. 회선 구성(cont’d)
점-대-점 회선 구성

8. 회선 구성(cont’d)
다중 포인트 회선 구성
Link

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
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. 토플로지 분류(Categories of topology)
Mesh
Star
Tree
Bus
Ring

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

13. Mesh(cont’d) 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

14. Mesh(cont’d) 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. Star
each device has a dedicate 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. Tree is a variation of a star simple shared hub(wiring concentrator)
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
switching hub
~ provides a switching function
intelligent Hub
~network management function

19. Tree(cont’d)
Tree topology
Hub
Hub
Hub

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

21. Bus
is multipoint. One long cable acts as a backbone to link all the device 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) Advantage Disadvantage ~ include ease of installation
~ include difficult reconfiguration and fault isolation

24. 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(dual ring)

25. Ring(cont’d)
Ring topology

26. 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. 전송모드(cont’d)
Transmission modes
Simplex
Half-duplex
Full-duplex

29. 전송모드(cont’d)
단방향(Simplex)
Direction of data
Monitor
Mainframe

30. 전송모드(cont’d) 반이중(Half-Duplex) Direction of data at time 1
Workstation
Workstation

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

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

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

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

35. 네트워크 분류(cont’d)
Single building LAN

36. 네트워크 분류(cont’d)
Multiple building LAN
Backbone

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

38. 네트워크 분류(cont’d)
MAN
Public city network

39. 네트워크 분류(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

40. 네트워크 분류(cont’d)
WAN

41. 2.5 인터네트워크(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

42. Internetworks(internet)

43. 2.6 요약 숙제
Exercise 3,5,7