Cabling and Connectors - buaamer81/IT130-Networking-Wiki GitHub Wiki

🔌 Cabling and Connectors

📘 Overview

This topic explores the physical media that interconnect network devices, including both copper and fiber-optic cabling, as well as their associated connectors.

Network cables are grouped into two main categories:

Copper Cabling
Fiber-Optic Cabling

🧷 Copper Cabling Types

🧵 Twisted Pair

1. UTP (Unshielded Twisted Pair)

Most common in modern Ethernet.
Inexpensive, flexible.
Sensitive to EMI.

2. STP (Shielded Twisted Pair)

Has extra shielding to block EMI.
Used in high-noise environments (e.g., factory floors).

📏 Category (CAT) Ratings

CAT	Max MHz	Max Mbps	Notes
CAT 3	16 MHz	16 Mbps	Obsolete
CAT 5e	100 MHz	1 Gbps	Standard for Ethernet
CAT 6	250 MHz	10 Gbps*	Up to 55m for 10GBaseT
CAT 6a	500 MHz	10 Gbps	Full 100m for 10GBaseT

🔘 Coaxial Cable

Central copper core, surrounded by insulator and braided shield.
Used for cable TV and older bus topologies.

Connectors:

BNC: Used in older Ethernet networks.
F-Connector: Screws on for secure coax connections (TV, cable modem).
Barrel Connector: Joins two coax cables.
Splitter: Splits a single coax line into multiple outputs.

🔗 Twisted Pair Connectors

RJ-11: Phone lines (2-pair).
RJ-45: Ethernet (4-pair).

💡 Fiber-Optic Cabling

Transmits light, not electricity. Immune to EMI. Ideal for long distances.

Types:

Multimode Fiber (MMF): Uses LEDs. Short distances.
Single-Mode Fiber (SMF): Uses lasers. Long distances.

Fiber Cable Components:

Core
Cladding
Buffer
Jacket

📏 Common size: 62.5/125 µm

🔌 Fiber-Optic Connectors

Connector	Features
ST	"Snap and twist" bayonet.
SC	"Stick and click", square shape.
LC	"Little connector", small duplex connector.
FC	Screw-in, used in high-vibration setups.
MT-RJ	SFF duplex connector, common with Cisco gear.

🧠 Exam Tip

Know how to visually identify RJ-45, RJ-11, ST, SC, LC, and BNC.
Be familiar with Category ratings and when to use UTP vs. STP.