[Computer Networks] Network 기본 개념

컴퓨터 네트워크 - 기본 개념

- Network Types (LAN, WAN)

- Network Criteria

- Physical topology

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Computer network

- a set of computers sharing resources located on or provided by network nodes

- The computers use common communication protocos over digital interconnections to communicate with each other

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Internet

- the largest computer network

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Networks

- the interconnection of a set of devices capable of communication

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Connecting device

- ex) Router, Switch, Modem (moduator-demodulator)

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Data

- information presented in whatever form is agreed upon by the groups creating and using it

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Billions of connected computing devices

- hosts = end systems

- runninngs net work apps at Internets "edge"

 

-> 네트워크에 연결된 수많은 기기들 (핸드폰, 데탑, 태블릿 등...)

이들을 host = end system 이라함

end system 은 인터넷의 edge 에 위치해있기 때문에 Network Edge 라고도 함

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Packet switches

- forward packets

- routers, switches

 

-> 패킷을 온전히 다 수신한 후 저장 (store-and-forward)

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Network Types

 

LAN (Local Area Network)

- usually privately owned

- connects some hosts in a single office, building, or campus

- LANs today are connected to each other and to WANs to create communication at a wider level

 

WAN (Wide Area Network)

- also an interconnection of devices capable of communication

- has a wider geographical span

- interconnects connecting devices such as switches, routers, or modems

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Network criteria (기준)

- Performance 성능

- Reliability 신뢰성

- Security 보안

 

Performance

- includes transmit time and response time

- transmit time : amount of time required for a message to travel from one device to another

- response time : elapsed time (경과 시간) between an inquiry and a response

 

Reliability

- the accuracy of delivery

- measured by the frequency of failure and the time it takes a link to recover from a failure

 

Security

- includes

- protecting data from unauthorized access

- protecting data from damage and development

- implementing policies and procedures for recovery from data losses

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Physical topology

- the way in which a network is laid out physically

- topology of a network is the geometric representation of the links and nodes

- ex) Mesh topology, Star topology, Bus topology, Ring topology

 

Mesh topology

- every device has a dedicated point-to-point link to every other device

- need n(n-1) physical links

- every device on the network must have n-1 I/O ports to be connected to other n-1 stations

 

Star topology

- each device has a dedicated point-to-point link only to a central controller (switch or hub)

- does not allow direct traffic between devices

 

Bus topology

- multipoint

- one long cable acts as a backbone to link all the devices in a network

- drop line : a connection running between the device and the main cable

- tap : connector

 

Ring topology

- each device has a dedicated point-to-point connection with only the two devices on either side of it

- a repeater regenerates the bits and passes them along

 

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