Network ConnectionsTextbook Chapter 8 265 to 270

Efficiency in networks depends on:

1. Type of access

2. Transmission Media

3. Type of connection

1. Type of Access

• Direct access: A dedicated, direct connection through a LAN

• Remote access: Network access via phone line, TV cable system or wireless link.

I. What type of access to the prepa TEC server, does your laptop have when being connected at school?

II. What type of access to the prepa TEC server, does your laptop have when being connected at home?

2. Transmission MediaMedia refers to the means used to link a network’s nodes together.

a) Twisted-pair cables.

b) Coaxial cables.c) Fiber-optic

cables.d) Wireless media

(Wi-Fi, infrared, bluetooth)

a) Twisted-pair cables• They normally consist of

four pairs of wires.• Each pair has two wires

separately insulated in plastic and then twisted around each other.

• Nothing shields this type of wire from outside interference.

• New cables support up to 1 Gbps (gigabit per second)

b) Coaxial cables• It consists of a rigid copper wire, surrounded by

insulating material.• It supports transmission speeds up to 10 Mbps

(megabits per second).• It is more expensive than twisted-pair cables• It is becoming less popular as twisted-pair technology

improves.

c) Fiber-optic cables

• It is a thin strand of glass that transmits light rather than electric current.

• Its transmission speed approaches 100Gbps.

• It is immune to electromagnetic interference.

• It is extremely fast, it can carry enormous number of messages simultaneously and it is very secure.

d) Wireless Media: Wi-Fi• The most popular is

known as Wi-Fi (Wireless Fidelity)

• It uses radio signals that travel through air from a base station up to 46 meters away (150 feet).

• It is not as fast as a cable connection.

e) Wireless Media: Infrared• It sends and receives

digital information over short distances.

• It is not widely used because of line-of-sight limitations (it cannot pass through walls).

• Share of data is “beamed” through infrared links .

f) Wireless Media: Bluetooth• Overcomes

differences between mobile phones, handheld devices and computers.

• It makes possible communication between all those devices regardless their operating system.

IV. Which transmission media is the fastest?

V. Which transmission media do you have at home?

VI. Which transmission media does the highschool have?

3. Type of connections

• Connection to Internet could be through

–phone line and a modem

–through broadband connections

–through fiber-optic connections.

Bandwidth• In all cases, the bandwidth determines the data

transfer rate – the quantity of data that can be transmitted through a communication medium in a given amount of time.

• Large bandwidths are measured in kilobits (thousands of bits) or megabits (millions of bits) per second.

Broadband connectionsConnection with much greater bandwidth than

standard modems are:Digital Subscriber Line (DSL) uses standard

phone lines and is provided by phone companies in many areas.

Cable modems provide fast network connections through cable television networks in many areas.

High-speed wireless connections can connect computers to networks using radio waves rather than wires.

Satellite dishes can deliver fast computer network connections as well as television programs.