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Basic Concepts Prof. Choong Seon HONG Kyung Hee University 1 Basic Concepts Five general concepts provide the basis for the relationship between the communicating devices. Line configuration Topology Transmission mode Categories of Networks Internetworks Kyung Hee University 2 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 Kyung Hee University Multipiont 3 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 Kyung Hee University 4 Line configuration (cont’d) 점-대-점 회선 구성 Link Kyung Hee University 5 Line configuration (cont’d) 점-대-점 회선 구성 Link Kyung Hee University 6 Line configuration (cont’d) 점-대-점 회선 구성 Kyung Hee University 7 Line configuration (cont’d) 다중 점 회선 구성 Kyung Hee University 8 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) Kyung Hee University 9 접속형태 분류(Categories of topology) Topology Mesh Kyung Hee University Star Tree Bus Ring 10 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. Kyung Hee University 11 그물형(cont’d) Mesh topology Kyung Hee University 12 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. Kyung Hee University 13 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 Kyung Hee University 14 스타형 (Star : 성형) Each device has a dedicated point-to-point link only to a central controller, usually called a hub Kyung Hee University 15 Star (cont’d) Star topology Kyung Hee University 16 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 Kyung Hee University 17 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 Kyung Hee University 18 Tree (cont’d) Tree topology Kyung Hee University 19 Tree (cont’d) Advantage & Disadvantage are generally the same as those of a star Kyung Hee University 20 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 Kyung Hee University 21 Bus (cont’d) Bus topology Kyung Hee University 22 Bus (cont’d) Advantages ~ include ease of installation Disadvantages ~ include difficult reconfiguration and fault isolation Kyung Hee University 23 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 Kyung Hee University 24 Ring (cont’d) Ring topology Kyung Hee University 25 혼합형(Hybrid topology) Kyung Hee University 26 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 Kyung Hee University 27 Transmission Mode (cont’d) Transmission modes Simplex Kyung Hee University Half-duplex Full-duplex 28 Transmission Mode (cont’d) 단방향 (Simplex) Kyung Hee University 29 Transmission Mode (cont’d) 반이중(Half-Duplex) Kyung Hee University 30 Transmission Mode (cont’d) 전이중(Full-Duplex) Kyung Hee University 31 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 Kyung Hee University 32 Categories of Networks (cont’d) Network Local area networks (LAN) Kyung Hee University Metropolitan area network (MAN) Wide area network (WAN) 33 Categories of Networks (cont’d) LAN(Local Area Networks) ~ is usually privately owned and links the devices in a single office, building or campus Kyung Hee University 34 Categories of Networks (cont’d) Kyung Hee University 35 Categories of Networks (cont’d) MAN(Metropolitan Area Networks) ~ is designed to extend over an entire city Kyung Hee University 36 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 Kyung Hee University 37 Categories of Networks (cont’d) WAN Kyung Hee University 38 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 Kyung Hee University 39 Internetworks (cont’d) Internetwork (internet) Kyung Hee University 40