Lesson 2.5: Physical Infrastructure

Module: 2 – Networking for Security Professionals

Prerequisites: Lesson 2.4 (PoE)

Estimated Time: 45–60 Minutes

By the end of this lesson, you will be able to:

Select the correct copper cable category (Cat5e, Cat6, Cat6A) for specific bandwidth and distance needs.
Differentiate between T568A and T568B termination standards and avoid “Split Pairs.”
Compare Single-Mode (OS2) and Multi-Mode (OM3/OM4) fiber optics and match them to the correct SFP modules.
Justify the use of Shielded (STP) cable for outdoor camera installations.

While wireless exists, 99% of professional security devices rely on copper twisted-pair cabling.

You will encounter three main types. Using the wrong one can limit future upgrades.

Category	Max Speed	Max Frequency	Use Case
Cat5e	1 Gbps	100 MHz	Legacy/Budget. Fine for standard 2MP cameras, but phasing out.
Cat6	1 Gbps / 10 Gbps*	250 MHz	The Standard. 1Gbps to 100m. Can do 10Gbps only up to 55m. Use for all general IP cameras.
Cat6A	10 Gbps	500 MHz	High Performance. Full 10Gbps to 100m. Thicker, harder to bend. Use for Wireless Access Points or Server Uplinks.

UTP (Unshielded Twisted Pair): Standard office cable. Plastic jacket, 4 twisted pairs.
STP/FTP (Shielded/Foil Twisted Pair): Contains a metal foil wrap and a “Drain Wire.”
- CRITICAL RULE: Always use Shielded Cable for outdoor cameras.
- Why? Wind creates static charge on the camera housing. Lightning creates ground loops. The “Drain Wire” carries this excess energy back to the switch’s ground, saving the camera from frying during a storm.

Inside the cable are 8 color-coded wires. The order in which you crimp them into the RJ45 jack matters.

T568A: (Green pair first). Often used in government/residential.
T568B: (Orange pair first). The Commercial Standard. 90% of businesses use B.

The Golden Rule: Pick one and stick to it on both ends.

If one end is A and the other is B, you create a “Crossover Cable” (rarely needed today).
If you mix colors randomly, you create a “Split Pair.” The data will work at 10Mbps but fail at 1000Mbps, causing ghosting or packet loss.

Copper dies at 100 meters (328 ft). For perimeters, parking lots, or connecting buildings, you need glass.

Core Size: Thick core (50 microns). Uses LED light.
Color: Aqua (OM3) or Violet (OM4) jacket.
Range: Up to ~300-400 meters for 10Gbps.
Use Case: Connecting a camera closet to a server room within the same building. Cheaper electronics.

Core Size: Tiny core (9 microns). Uses Laser light.
Color: Yellow (OS2) jacket.
Range: Miles (10km, 40km+).
Use Case: Perimeter fence lines, linking separate buildings, city-wide surveillance.
Note: While the cable is cheap, the electronics (lasers) are slightly more expensive. However, the industry is shifting to Single-Mode for everything due to its unlimited bandwidth potential.

Fiber doesn’t plug directly into a switch. It plugs into a Transceiver (SFP) module, which then slides into the switch.

Matching Rule: An Orange Fiber (Multi-mode) needs a Multi-mode SFP. A Yellow Fiber (Single-mode) needs a Single-mode SFP. They are not interchangeable.

“The light is blinking” is not a test.

Continuity Test (The $50 Tester):
- Checks: “Did I connect Pin 1 to Pin 1?”
- Verdict: Good for basic troubleshooting, but doesn’t tell you if the cable can handle Gigabit speeds.
Qualification (The $500 Tester):
- Checks: “Can this cable sustain 1Gbps?”
- Verdict: Great for technicians verifying a repair.
Certification (The $10,000 Fluke):
- Checks: Crosstalk (NEXT), Return Loss, Impedance.
- Verdict: Mandatory for large projects. It generates a PDF report proving every single cable passed standards. If you don’t Certify, the manufacturer usually voids the 20-year warranty.