[2강] 인터페이스와 케이블

2강 이론

• Ethernet
  • a collection of network protocals/standards
• bit
  • 0 / 1
  • 1 Kb = 1,000 bits
  • 1 Mb = 1,000,000bits
  • 1 Gb = 1,000,000,000bits
  • 1 Tb = 1 ,000,000,000,000bits
• byte
  • 8 bits
• Speed
  
  • is measured in bits per second (Kbps, Mbps, Gbps, etc)
•  Ethernet Standards
  • IEEE 802.3 standard in 1983
    • IEEE = institue of Electrical and Electronics Engineers

Ethernet Standards (copper)

• Base
  • baseband signaling
• T
  • twisted pair
• UTP Cables
  • Unshielded Twisted Pair
  • Twisted Pair
    • protects against EMI
      • EMI = Electromagnetic Interface
        • 전자기 간섭
        • 하나의 전자기기에서 발생한 불필요한 전자파나 노이즈가 주변 기기 회로에 영향을 주어 오작동을 일으키는 현상
  • 10 BASE - T / 100 BASE - T = 2 pairs (4 wires)
    • Full-Duplex transmission
      • both devices send data at the same time, and no problems like collisions will occur because they use separate wires to transmit and receive data
    • a straight-through cable
    • a crossover cable
    • Auto MDI-X
      • crossover cable을 사용하지 않더라도, 감지해서 자동으로 tx와 rx를 변환해주는 feature

 

• 1000 BASE - T / 10 GBASE - T = 4 pairs (8 wires)
  • Bidirectional

• SFP Transceiver
  • Small Form-Factor Pluggable
  • Fiber Optic Cable
    • send light over glass fibers
    • 1: the fiberglass core itself
    • 2: cladding that reflects light
    • 3: a protective buffer
    • 4: the outer jacket of the cable

• Multimode Fiber
  • the center represents the fiberglass core
  • the blue represents cladding that reflects light
  • Core diameter is wider than single-mode fiber
  • Allows multiple angles (modes) of light waves to enter the fiberglass core
  • Allows longer cables than UTP, but shorter cables than single-mode fiber
  • Cheaper than single-mode fiber

• Singlemode Fiber
  • the center represents the fiberglass core
  • the blue represents cladding that reflects light
  • Core diameter is narrower than multimode fiber
  • Light enters at a single angle mode from a laser based transmitter
  • Allows longer cables than both UTP and multimode fiber
  • More expensive than multimode fiber

Fiber Optic Cable Standards

 

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2강 QUIZ

키워드: connect two old routers together with a UTP cable

a) a straight-through cable: 이것은 두 라우터를 연결하는데 있어 적합하지 않습니다. Tx와 Rx의 핀 번호가 같기 때문입니다. a crossover cable 을 사용하거나, Auto MDI-X mode 기능을 지원하는 디바이스 끼리 연결해야 합니다

 

키워드: wants to connect switches / 150 meters apart . keep costs down

c) Multimode fiber: UTP는 100m 제한이 있기 때문에 적합하지 않고, Single-mode fiber는 Multimode fiber 보다 비쌉니다.

 

키워드: wants to connect switches / 3 kilometers meters apart . keep costs down

b) Single-mode fiber: 3km 이기에 Single-mode fiber 외에는 별다른 선택지가 없습니다 (주어진 것 중에서)

 

a) They would operate normally: Auto MDI-X 를 지원하네요! 별다른 문제 없이 동작합니다

 

키워드: connect many end hosts to a switch / the same office floor

a) UTP: 대부분의 호스트는 fiber cable 로 스위치에 연결하는 게 가능하지 않습니다. 그리고 대부분의 스위치는 충분한 개수의 SFP도 없죠.

 

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2강 실습