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Difficulty: Very hardPhysical Interface and Cabling Types

A network engineer is designing a 10 Gbps backbone link between two switches located in separate campus buildings that are 450 meters apart. The campus conduit contains both multi-mode optical fiber (OM2 and OM3) and single-mode optical fiber (OS2). The link must achieve maximum throughput without signal degradation. Which optic transceiver and cabling combination must be selected to fulfill this requirement?

  1. 10GBASE-LR SFP+ transceiver over single-mode fiber (OS2)Answer
  2. B
    10GBASE-SR SFP+ transceiver over OM3 multi-mode fiber
  3. C
    10GBASE-T SFP+ transceiver over Category 6A unshielded twisted-pair copper cable
  4. D
    10GBASE-CR Direct Attach Copper (DAC) crossover cable with Auto-MDIX enabled

Answer

10GBASE-LR SFP+ transceiver over single-mode fiber (OS2)
The 10GBASE-LR standard uses long-wavelength optics (1310 nm) over single-mode fiber (SMF/OS2), which easily supports a distance of 450 meters (up to a 10 km maximum limit).

Step-by-Step Solution

1
Analyze required distance and speed parameters
The requirement specifies a 10 Gbps Ethernet connection across a distance of 450 meters.
Different Ethernet physical layer standards (transceivers and cable types) have strict maximum reach limits.
2
Evaluate multi-mode fiber (MMF) standard limits for 10GBASE-SR
10GBASE-SR over OM2 reaches up to 82 meters; over OM3 reaches up to 300 meters; over OM4 reaches up to 400 meters. None of the available MMF options reach 450 meters.
Short-wavelength (850 nm) lasers on multi-mode fiber suffer from modal dispersion over long distances.
3
Evaluate copper cabling options
10GBASE-T UTP twisted-pair cable max distance is 100 meters; Direct Attach Copper (DAC) cables max distance is 7–10 meters.
Electrical signal attenuation limits copper cabling for high-speed long-distance links.
4
Evaluate single-mode fiber (SMF/OS2) options
10GBASE-LR operates using long-wavelength (1310 nm) lasers over single-mode optical fiber and supports distances up to 10 kilometers (10,000 meters).
Single-mode fiber avoids modal dispersion, making it the ideal choice for distances exceeding 400 meters.

Key Concept

Ethernet optical transceiver standards, distance limitations, and fiber cable types (10GBASE-SR vs 10GBASE-LR)
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Topics

Physical Interface and Cabling Types

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