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

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

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

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

회선 구성(cont’d) 점-대-점 회선 구성 Link

회선 구성(cont’d) 점-대-점 회선 구성 Link

회선 구성(cont’d) 점-대-점 회선 구성

회선 구성(cont’d) 다중 포인트 회선 구성 Link

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

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

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.

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.

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 5000.

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

Star each device has a dedicate point-to-point link only to a central controller, usually called a hub.

Star(Cont’d) Star topology

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

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

Tree(cont’d) Tree topology Hub Hub Hub

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

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

Bus(cont’d) Bus topology

Bus(cont’d) Advantage Disadvantage ~ include ease of installation ~ include difficult reconfiguration and fault isolation

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)

Ring(cont’d) Ring topology

Hybrid topology

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

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

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

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

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

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

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

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

네트워크 분류(cont’d) Single building LAN

네트워크 분류(cont’d) Multiple building LAN Backbone

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

네트워크 분류(cont’d) MAN Public city network

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

네트워크 분류(cont’d) WAN

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

Internetworks(internet)

2.6 요약 숙제 Exercise 3,5,7