Transcript Chap. 2 Basic concepts

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
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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
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회선 구성(cont’d)
점-대-점(Point-to-point)
~ provides a dedicated link between two devices.
멀티포인트(Multipoint)
~ is one in which more than two specific devices
share a single link
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회선 구성(cont’d)
점-대-점 회선 구성
Link
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회선 구성(cont’d)
점-대-점 회선 구성
Link
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회선 구성(cont’d)
점-대-점 회선 구성
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회선 구성(cont’d)
다중 포인트 회선 구성
Link
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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
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토플로지 분류(Categories of topology)
Topology
Mesh
Star
Tree
Bus
Ring
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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.
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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.
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Mesh(cont’d)
Mesh topology
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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
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Star
each device has a dedicate point-to-point link
only to a central controller, usually called a
hub
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Star(Cont’d)
Star topology
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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
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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
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Tree(cont’d)
Tree topology
Hub
Hub
Hub
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Tree(cont’d)
Advantage & Disadvantage
are generally the same as those of a star
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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
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Bus(cont’d)
Bus topology
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Bus(cont’d)
Advantage
~ include ease of installation
Disadvantage
~ include difficult reconfiguration and fault
isolation
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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)
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Ring(cont’d)
Ring topology
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Hybrid topology
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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
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전송모드(cont’d)
Transmission modes
Simplex
Half-duplex Full-duplex
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전송모드(cont’d)
단방향(Simplex)
Direction of data
Mainframe
Monitor
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전송모드(cont’d)
반이중(Half-Duplex)
Direction of data at time 1
Workstation
Direction of data at time 2
Workstation
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전송모드(Full-Duplex)
전이중(Full-Duplex)
Direction of data at all the time
Workstation
Workstation
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2.4 네트워크 분류(categories of Networks)
three primary categories
LAN
MAN
WAN
size, ownership, distance it cover, physical
architecture
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네트워크 분류(cont’d)
Network
Local area networks
(LAN)
Metropolitan area network
(MAN)
Wide area network
(WAN)
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네트워크 분류(cont’d)
LAN(Local Area Networks)
~ is usually privately owned and links the devices in
a single office, building or campus
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네트워크 분류(cont’d)
Single building LAN
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네트워크 분류(cont’d)
Multiple building LAN
Backbone
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네트워크 분류(cont’d)
MAN(Metropolitan Area Networks)
~ is designed to extend over an entire city
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네트워크 분류(cont’d)
MAN
Public city network
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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
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네트워크 분류(cont’d)
WAN
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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
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Internetworks(internet)
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