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NETWORKING MEDIA

Transmission media - Enables computers to send and receive signals to one another

Physical Media

Types of Physical Cable Media

Twisted Pair
Twisted Pair Cable uses one or more pairs of twisted copper wires to transmit signals

2 types of twisted pair cables

UTP – Unshielded Twisted Pair (Most common)
STP – Shielded Twisted Pair (Protection against EMI)

Twisted Pair Cable Ratings

Use on 10BaseT, 100BaseTX or 1000BaseT Networks

CAT cables usually connect to an RJ45 connector

The assignments of wire pairs to plug and jack pins are as follows:

TIA Standard 568A

TIA Standard 568B

Transmission

 

Coaxial
Coaxial cable, commonly called coax, has two conductors that share the same axis.
Coaxial

Thinnet or 10Base2 cost is cheap RG58 wire with 50 Ohms Terminator
Must use a T connector with BNC and last computer on both ends must be terminated
No more than 30 nodes per segment
Nodes must be space 0.5 meters apart

Thicknet or 10Base5 moderate costs RG8 rated at 50 Ohms connects to an AUI or DIX NIC thru a vampire tap
Nodes must be 2.5 meter intervals
No More than 100 Nodes per segment

Note * Some Cable Television and Sattelite Signals also use an RG6 cable with an F connector

Coaxial and the 5-4-3 Rule
When using coaxial media the rule specifies that the network is limited to a total of 5 cable segments, using no more than 4 repeaters and only 3 segments on the network can be populated
With any cables watch out for EMI, Fire Rating, Cross Talk and Attenuation

Fiber-Optic
Fiber-Optic cable transmits light signals rather than electrical signals.

Most expensive physical media usually use as backbone or a high speed connection


Types of Fiber Optic Standards

Multimode Fiber (MMF) - use LED light emitting diode found on most high speed networks

Singlemode Fiber (SMF) - use Laser to transmit signal (very rare)

Fiber Optic Connectors

ST – Straight Tip Connector
SC – Square Connector

SFF (Small Form Factor) Fiber Optic connectors

MTRJ- Mechanical Transfer Registered Jack

LC – Local Connector

Fiber Optic Advantages:

Speed, Distance, Security and Immune to EMI

Fiber Optic Disadvantages:
Cost, Difficulty of installation and Flexibility

Transmission Degradation of Physical Media

Attenuation – Loss of signal as it goes to a transmission media.

Crosstalk – a form of EMI caused by wires next to each other interpreting with signals as they travel through the transmission media.

Dispersion – applies to fiber optic cables.

Fire Ratings
Plenum (Non Flammable fire rating for cables) vs. PVC Poly Vinyl Chloride

Wireless Media

Radio Signals – use radio signals to communicate, the three types of radio waves are low power, high power and spread spectrum broadcasts. (Bluetooth, WiFi)

Microwave Transmission - most popular long distance transmissions found in networks.
It uses line-of-sight communication.
Microwave systems consist of 2 radio transceivers: one to transmit and one to receive. These antennas are usually installed on towers to give them more distance and speeds.

Infrared- uses infrared light to transmit signals. Infrared signals cannot penetrate walls or other thick objects (Remote Television, infrared mouse, infrared keyboard)

Satellite - Uses Satellite Technology to transmit signals. (Direct TV and Hughes)