🌐 Cabling and Network Topology

Understanding how data travels across physical and logical networks is essential for designing, troubleshooting, and maintaining IT infrastructure. This guide covers:

Network Topologies
Cable Types (Coaxial, Twisted Pair, Fiber Optic)
Connectors and Standards
Fire Safety Ratings

🕸️ Network Topology

Topology describes the structure and layout of network connections, both physical and logical.

📌 Common Topologies

Topology	Description
Point-to-Point	Direct connection between two devices
Star	All devices connect to a central hub or switch
Mesh	Devices are interconnected (full or partial mesh)
Hybrid	Combination of two or more topologies
Logical	How data flows regardless of physical layout
Spine and Leaf	Used in data centers; scalable and low-latency

🏗️ Network Architectures

Client-Server: Centralized server provides services to clients
Peer-to-Peer (P2P): Devices share resources equally
Distributed Architecture: Services are spread across multiple nodes
Data Center Fabric (Spine-Leaf): Used in high-speed environments

🔌 Coaxial Cables

🧵 Structure

Central copper core
Dielectric insulator
Shielding (braid or foil)
Outer jacket

📦 Types

Type	Use Case
`RG-6`	Cable TV, satellite, broadband
`RG-59`	CCTV, low-frequency video
`RG-11`	Long-distance, less signal loss

🔗 Connectors

BNC – CCTV, broadcast
F-type – Cable TV
DAC (Direct Attach Copper) – High-speed short links in data centers

✅ Pros and ❌ Cons

Advantages

Shielded against EMI
Durable and easy to install

Disadvantages

Bulky
Limited bandwidth
Not ideal for modern high-speed networks

🧵 Twisted Pair Cables

⚡ EMI Protection

Twisting reduces Electromagnetic Interference (EMI)
Comes in Shielded (STP) and Unshielded (UTP) types

📏 Distance

Typical maximum length: 100 meters (328 feet)

🧩 Connectors

RJ-45 – Ethernet
RJ-11 – Telephone

🧪 Standards

Category	Speed	Frequency	Use
Cat 5	`100 Mbps`	`100 MHz`	Older Ethernet
Cat 5e	`1 Gbps`	`100 MHz`	Enhanced crosstalk control
Cat 6	`1–10 Gbps`	`250 MHz`	High-speed Ethernet
Cat 6a	`10 Gbps`	`500 MHz`	Shielded for EMI resistance
Cat 7	`10 Gbps`	`600 MHz`	Heavily shielded, less common
Cat 8	`25–40 Gbps`	`2000 MHz`	Short runs in data centers

🧬 Fiber Optic Cables

🔍 Types

Type	Core Size	Distance	Light Source
Single-Mode	`8–10 µm`	Long (`>10 km`)	Laser
Multi-Mode	`50–62.5 µm`	Short (`<2 km`)	LED

🎨 Cable Colors

Color	Mode
Yellow	Single-mode
Orange	Multi-mode `OM1/OM2`
Aqua	Multi-mode `OM3/OM4`

🔗 Connectors

Connector	Type	Description
ST	Bayonet	Push & twist, older installations
SC	Push-pull	Square shape, datacenter use
FC	Threaded	Industrial use, vibration resistant
LC	Small-form	Common modern duplex connection
MTRJ	Compact	Duplex in a single connector

🔁 Polishing Types

UPC (Ultra Physical Contact): Blue, low return loss
APC (Angled Physical Contact): Green, even lower return loss, better for video & long fiber runs

⚙️ How Fiber Works

Light pulses travel through the glass core
Internal reflection keeps the light contained
Immune to EMI, supports ultra-high-speed over long distances

🔥 Fire Safety Ratings – Cable Jacket Types

Rating	Use Case	Description
Plenum	Air ducts/ceilings	Highest fire safety, low-smoke, flame-retardant
Riser	Between floors	Fire-resistant, not for air ducts
Non-Plenum	Open spaces	No fire safety requirements

🧯 Always follow local building codes. Use Plenum-rated cables in air-handling spaces like ceiling voids.

✅ Summary

Cable Type	Max Distance	EMI Resistant	Cost	Use Cases
Coaxial	`~500m`	Medium	Low	CCTV, legacy cable TV/internet
Twisted Pair	`100m`	STP = Yes	Low/Medium	LAN, VoIP, office networks
Fiber Optic	`>10km`	Yes	High	High-speed backbone, datacenters

💡 Choosing the right cabling and topology improves speed, scalability, and safety of your network infrastructure.