CCNA Network Media Types

As we all know what the basic building blocks of network are. Now we are going to look about appropriate media used to interconnect the network devices and hosts. Network media is the actual path over which an electrical signal travels from one device to another. We are going describes about various types of network media, types

Network Media Type Coaxial Cable

Oliver Heaviside a mathematician invented coaxial cable in 1880. Coaxial cable was popular in mid 80’s mainly used in thinnet (10BASE2) and thicknet (10BASE5) networks. Centre of the cable is an inner conductor; a braided copper is surrounded by dielectric insulator. An insulator shield is then covered with metal foil. The whole assembly is then wrapped in insulating plastic.

We all have seen coaxial cable in our homes on cable TV. This will be similar to our cables used in network the difference is video or TV uses higher impedance cable RG6 and RG59 are used in cable TV’s. In Ethernet it uses 50Ω cable RG58 for thinnet and RG8 for thicknet. Both of these cables RG58 and RG6 have maximum transmission speed of 10 Mbps.

A BNC (Bayonet Neil-Concelman, or British Naval Connector) connector is used to connect a computer to a coaxial cable in a thinnet (10BASE2) Ethernet network. Now days twisted replaced coax cables with support higher transmission speeds.

Coaxial Cable	Impedance	Use
RG58	50	Computer, Radio
RG59	75	Television
RG8	50	Computer, Radio
RG6	75	Television

Network Media Twisted Pair

We use twisted pair of cables in telephone networks and in Ethernet especially in LAN with in 100 m. Wires are twisted each other in order to reduce EMI (Electro Magnetic Interference). We know that when current flows through the conductor a magnetic field is induced around the conductor, thus if we place two conductors close enough the magnet field generated by them will opposite to each other. So it cancels each other thus the disturbance in the line can be cancelled. Therefore the twist should be tight enough, if it is loose can lead to crosstalk.

Categories of UTP cables	Common Use
Cat 1	Used in telecommunication an don’t support data transmission
Cat 2	Can transmit data at 4 Mbps
Cat 3	Used in telephone have speed of 10 Mbps 10BASE-T
Cat 4	Used in token ring network have speed of 16 Mbps
Cat 5	100BASE-TX have speed of 100 Mbps
Cat 5e	1000BASE-T Uses 24 gauge wire have speed of 1 G bps
Cat 6	1000BASE-T Uses 22 gauge wires have speed of 1 G bps reduced crosstalk.
Cat 6a (a means augmented)	10GBASE-T have speed of 10 G bps immune to crosstalk

Thus we can conclude that twisted pair is mainly used in Ethernet and it have a distance limitation of 100 m, UTP cable is inexpensive and cat 6a cables have a speed of 10 Gbps and highly immune to EMI.

Network Media Fiber Optic Cable

Fiber-Optic cable uses pulses of light in order to transmit data binary data presence of light means binary one absence means zero. Since it uses light its immune to EMI. We cannot consider fiber-optic cables as wireless; even though it’s an electromagnetic wave it is in a guided media. So we wireless is an electromagnetic waves that is radiated or unguided.

The light is passing through the core and the cladding. The core is made of highly purified glass that having high refractive index. Core is surrounded by a low refractive index material made up of glass or plastic. Thus if light enters to core from a certain called angle of incidence if it greater than critical angle will not escape through the material, it get trapped in the material of higher refractive index (core) and get totally reflected through the material, this phenomena is known as total internal reflection.

Types of fiber-optic cables

This type of cabling support greater speed and have larger distance coverage. It’s immune to electromagnetic interference and this is very expensive compared to other media. There are two types of fiber-optic cables. Distance of coverage depends on fiber transceiver, wavelength, cable type, size of core (micron), and modal bandwidth of the fiber.

Single-mode fiber (SMF)

Single-mode fiber can pass only one wavelength of light and have a smaller core dia. This type of cable is used as backbone to mainframe networks. SMF uses lasers to generate light beam and have greater coverage than MMF. SMF is expensive than MMF.

Multi-mode fiber (MMF)

MMF has a large diameter compared to SMF, so allows light to enter different angles. It uses LED as light generator. It is less expensive than SMF and low distance coverage.

Fiber-Optic Connectors Commonly Used

Standard Connector (SC): Used in Telecom also known as Square Connector
Straight Tip (ST): Mainly used for MMF fiber.
Lucent Connector (LC): Used for high density connection also known as Local Connector
Media Termination - Recommended Jack (MT-RJ): Used in duplex multimode connection.

Wireless as a Networking Media

Wireless Network is now gaining popularity and they use unguided electromagnetic waves to transmit data. Radio Frequencies (RF) and Infrared Red (IR) waves are used for wireless network. For a wireless LAN you need a wireless access point and also need wireless NIC on host to connect to the access point.

No physical medium required because electromagnetic waves can travel through space and vacuum. Wireless frequencies from 3 kHz to 300 GHz are used from RF Spectrum. It provides data transmission rates range from 9 kbps to 54 Mbps.

About Jas Jashim

Jas Jashim Author and Founder of ccnaguru.com.He is electronics and communication engineer by education, working in networking field.Started this blog as an hobby to help you in ccna studies.