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Difficulty: HardPhysical Interface and Cabling Types

A network engineer is evaluating cabling standards and optical transceiver specifications for a campus network refresh. When connecting switch interfaces across various media types, which two statements correctly describe physical interface and cabling characteristics according to Ethernet standards? (Select two.)

  1. 10GBASE-SR transceivers operate over multimode fiber using an 850 nm wavelength and can reach up to 300 meters on OM3 cabling.Answer
  2. 1000BASE-T Ethernet requires all four wire pairs in Category 5e or higher UTP cabling to operate concurrently in full-duplex mode.Answer
  3. C
    100BASE-TX crossover cables swap pins 1 and 2 with pins 4 and 5 at the opposite RJ-45 connector while keeping pins 3 and 6 straight through.
  4. D
    Single-mode fiber (SMF) cores typically measure 50 to 62.5 microns in diameter, resulting in high modal dispersion compared to multimode fiber (MMF).
  5. E
    1000BASE-LX transceivers use 1310 nm long-wavelength lasers and are strictly restricted to single-mode fiber infrastructure.

Answer

The correct statements are that 10GBASE-SR transceivers operate over multimode fiber using an 850 nm wavelength reaching up to 300 meters on OM3 cabling, and 1000BASE-T Ethernet requires all four wire pairs in Category 5e or higher UTP cabling to operate concurrently.
10GBASE-SR transceivers specify short-wavelength 850 nm light over multimode fiber with standard distance caps of 300 meters on OM3 and 400 meters on OM4. Additionally, 1000BASE-T requires all four copper pairs in Cat5e or better cables, transmitting full-duplex signals over all eight conductors simultaneously.

Step-by-Step Solution

1
Analyze optical fiber transceiver specifications
10GBASE-SR (Short Reach) uses 850 nm lasers over multimode fiber (MMF). It supports up to 300 m on laser-optimized OM3 MMF and 400 m on OM4 MMF.
Matching transceiver naming conventions (SR vs LR vs ER) to light wavelengths and distance limits is critical for optical link design.
2
Analyze twisted-pair copper transmission mechanics
1000BASE-T achieves 1 Gbps throughput across Category 5e/6 UTP by utilizing hybrid circuits that allow bi-directional transmission on all four pairs simultaneously.
10BASE-T and 100BASE-TX only use 2 pairs (4 wires), whereas Gigabit 1000BASE-T requires all 4 pairs (8 wires).
3
Evaluate and eliminate incorrect distractor claims regarding pinouts, fiber core diameters, and optic compatibility
Crossover cables swap pins 1/2 with pins 3/6. Single-mode fiber has a smaller core (9 microns) with no modal dispersion. 1000BASE-LX can run on MMF with a mode-conditioning patch cable.
Distinguishing between MMF and SMF physical attributes and recognizing optic deployment exceptions prevents physical layer design errors.

Key Concept

Physical Interface Standards and Cabling Specifications
Estimated Time:2m 0s
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Topics

Physical Interface and Cabling Types

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