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SCS2111 | Phase 4: Hardware, Media & Cabling Infrastructure
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SCS2111 Phase 4: Hardware & Cabling
PHASE 04

Hardware, Physical Media & Cabling Infrastructure

Mastering copper twisted-pair pinouts, fiber optics, attenuation formulas, network interconnection devices, and PoE standards.

1. Copper Twisted-Pair Cabling Standards

T568A Standard

T568A Wire Color Order

  1. White / Green
  2. Green
  3. White / Orange
  4. Blue
  5. White / Blue
  6. Orange
  7. White / Brown
  8. Brown
T568B Standard (Industry Default)

T568B Wire Color Order

  1. White / Orange
  2. Orange
  3. White / Green
  4. Blue
  5. White / Blue
  6. Green
  7. White / Brown
  8. Brown

Straight-Through vs Crossover Cables

  • Straight-Through Cable (T568B on both ends): Connects unlike devices (PC to Switch, Switch to Router).
  • Crossover Cable (T568A on one end, T568B on the other): Connects like devices (Switch to Switch, Router to Router, PC to PC). Note: Modern Auto-MDIX ports auto-detect and correct pin mismatch.

2. Fiber Optic Transmission Media

Long Haul Backbone

Single-Mode Fiber (SMF)

Small glass core diameter ($8.3 - 10\,\mu\text{m}$). Employs focused laser diodes. Light travels straight down core with zero modal dispersion.

  • Distance: Up to $40\,\text{km} - 100\,\text{km}$ without repeaters.
  • Used in ISP MAN/WAN backbones and inter-building links.
Intra-Building Data Center

Multi-Mode Fiber (MMF)

Larger core diameter ($50 - 62.5\,\mu\text{m}$). Employs VCSEL or LED light sources. Multiple light rays travel at varying reflection angles.

  • Distance: Limited to $300\,\text{m} - 550\,\text{m}$ due to modal dispersion.
  • Used inside enterprise server rooms and local rack uplinks.

3. Network Interconnection Devices & PoE Technology

Hubs (Layer 1) vs Switches (Layer 2)

Hubs broadcast incoming electrical signals to all ports (single collision domain). Switches learn MAC addresses and forward frames selectively per port (isolated collision domains).

Routers (Layer 3) & Power over Ethernet (PoE)

Routers connect separate networks using logical IP addresses. Power over Ethernet (IEEE 802.3af/at/bt) delivers up to 15.4W – 90W DC power over Cat6 cables to IP cameras and Wireless Access Points (WAPs).