The Internet Connection

Dial-up Internet Access

This is the most common basic type of connection available from ISPs (Internet Server Providers). In Dial-up connection, you use your computer, dial a phone number (provider by ISP) to get connected to server at Providers end through which you access Internet. It means you are not directly connected to Internet; you access the Internet through an Internet Service Provider.

ISDN (Integrated Services Digital Network)

The process of connecting to server to access Internet is almost same as Dial-up, but it offers connectivity through the use of Introduction to Internet :: 245  digital phone lines instead of Analog. It offers Internet connectivity at speeds of up to 128 Kbps, allows the user to receive or make calls simultaneously on the same line. ISDN comes through a regular telephone wire from the telephone pole on the street. The line combines two 64 Kbps channels to offer 128 Kbps bandwidth broken into three bands: One band for the ringing signal of your phone, one band for your telephone   conversation, and one band  for data transfer.

Leased Line Connection (Direct Internet Access)

A “permanent connection” between a computer system (single  CPU or LAN, and the Internet). It is generally used by larger institutions, corporate and government agencies. It involves establishing your own Internet gateway (connection) and payment  to have a direct full time line with the network. Your computers, in effect, become part of the Net. The main advantage of this connection is that: it is on line – 24 hrs a day, seven days a week, (24×7) and provides faster access. Dedicated links are established through an internet service provider who places a computer-controlled router (message
director) at your site. A router is used to connect your local network to the Internet, allow all the members of network to have complete access to Internet.

DSL (Digital Subscriber Line or Dedicated Service Line)

Broadband Connection DSL, an “always-on’ data connection is becoming widely available
these days. It can provide an excellent Internet connection. It connects your home or office to the Internet through the same telephone wire that comes from telephone pole on the street. Like ISDN, with DSL, user can make and receive telephone calls while connected to the Internet. The difference between DSL and dialup / ISDN is that a DSL Internet connection uses a high-speed dedicated circuit filtering out standard phone calls and Internet signals.

Cable

Cable provides an internet connection through a cable modem and operates over cable TV lines.  There are different speeds depending on if you are uploading data transmissions or downloading.  Since the coax cable provides a much greater bandwidth over dial-up or DSL telephone lines, you can get faster access.  Cable speeds range from 512K to 20 Mbps.

There are two type of cable; Coaxial and optic fibre. The first one is used by cable TV and that is common for data communications ( see image on the left ).
The cross-section of the cable shows a single centre solid wire made of copper surrounded by a copper mesh conductor. Between the main wire ( in the centre ) and the mesh conductor is an insulating dialectric. This dialectric ( blue part in the image ) has a large effect on the essential features of the cable. Depending on the material that isulator is made of, the cable has different inductance and capacitance values and these values affect how quickly data travels through the wire. The last layer is an outside insulator to protect the whole wire.

Data is transmitted through the rigid wire, while the outer copper mesh layer serves as a line to ground.

Optic Fibre.

Fibre-optic cables are strands of a special optical material as thin as a human hair that carry data ( files, videos .. ) over long distances. Now, there is not electrical signal. In Optical fibres data are carried as light signals

How Does an Optical Fiber Transmit Light?

What is the secret of optical Fibre? Why doesn’t the light ray escape from the strand?

Suppose you want to shine a torch beam down a long, straight corridor. Just point the beam straight down the corridor. — light moves in straight lines so the light will reach to the end of the corridor.
What if the corridor has a bend in it? . Just place a mirror at the bend to reflect the light beam towards the other side of the corridor.
What if the corridor has multiple bends? You might places as many mirrors as bends so that it bounces from side-to-side all along the corridor. This is what happens in an optical fibre.

Wireless

Wireless, or Wi-Fi, as the name suggests, does not use telephone lines or cables to connect to the internet.   Instead, it uses radio frequency.  Wireless is also an always on connection and it can be accessed from just about anywhere.  Wireless networks are growing in coverage areas by the minute so when I mean access from just about anywhere, I really mean it.  Speeds will vary, and the range is between 5 Mbps to 20 Mbps.

Satellite

Satellite accesses the internet via a satellite in Earth’s orbit. The enormous distance that a signal travels from earth to satellite and back again, provides a delayed connection compared to cable and DSL.  Satellite connection speeds are around 512K to 2.0 Mbps.

Cellular

Cellular technology provides wireless Internet access through cell phones.  The speeds vary depending on the provider, but the most common are 3G and 4G speeds.  A 3G is a term that describes a 3^rd generation cellular network obtaining mobile speeds of around 2.0 Mbps.  4G is the fourth generation of cellular wireless standards. The goal of 4G is to achieve peak mobile speeds of 100 Mbps but the reality is about 21 Mbps currently.

Eoc ( Ethernet over cable )

Is a technology that uses ethernet in the first mile with an RJ-45 jack connection that conventional ethernet cables use. Beyond the first mile, the connection is carried over a coax cable network.