Brief history of connection technologies.

In the 1990s, the Internet was typically used for data transfer. Transmission speeds were slow compared to the high-speed connections that are available today. The additional bandwidth allows for transmission of voice and video, as well as data. Today there are many ways to connect to the Internet. Phone, cable, satellite, and private telecommunications companies offer broadband Internet connections for businesses and home use.

Analog Telephone

Analog telephone, also called plain old telephone service (POTS), transmits over standard voice telephone lines. This type of service uses an analog modem to place a telephone call to another modem at a remote site, such as an Internet service provider. The modem uses the telephone line to transmit and receive data. This method of connection is known as dialup.

Integrated Services Digital Network

ISDN uses multiple channels and can carry different types of services; therefore, it is considered a type of broadband. ISDN is a standard for sending voice, video, and data over normal telephone wires. ISDN technology uses the telephone wires as an analog telephone service.

Broadband

Broadband is a technology that is used to transmit and receive multiple signals using different frequencies over one cable. For example, the cable used to bring cable television to your home can carry computer network transmissions at the same time. Because the two transmission types use different frequencies, they do not interfere with each other.

Broadband uses a wide range of frequencies that can be further divided into channels. In networking, the term broadband describes communication methods that transmit two or more signals at the same time. Sending two or more signals simultaneously increases the rate of transmission. Some common broadband network connections include cable, DSL, ISDN, and satellite. The figure shows equipment used to connect to or transmit broadband signals.

 

Exercise 2. Work in pairs. What problems do you have with networks? Make a list. Think about speed, compatibility, hardware and software.

Exercise 3. Read the text and fill in the table with the information.

Selecting an ISP for the customer.

Several WAN solutions are available for connecting between sites or to the Internet. WAN connection services provide different speeds and levels of service. You should understand how users connect to the Internet and the advantages and disadvantages of different connection types. The ISP that you choose can have a noticeable effect on network service.

There are four main considerations for an Internet connection:

· Cost

· Speed

· Reliability

· Availability

Research the connection types that the ISPs offer before selecting an ISP. Check the services available in your area. Compare connection speeds, reliability, and cost before committing to a service agreement.

POTS

A POTS connection is extremely slow, but it is available wherever there is a landline telephone. There are two major disadvantages of using the phone line with an analog modem. The first is that the telephone line cannot be used for voice calls while the modem is in use. The second is the limited bandwidth provided by analog phone service. The maximum bandwidth using an analog modem is 56 Kb/s, but in reality, it is usually much lower than that. An analog modem is not a good solution for the demands of busy networks.

ISDN

ISDN is very reliable because it uses POTS lines. ISDN is available in most places where the telephone company supports digital signaling to carry the data. Because it uses digital technology, ISDN offers faster connection times, faster speeds, and higher quality voice than traditional analog telephone service. It also allows multiple devices to share a single telephone line.

DSL

DSL allows multiple devices to share a single telephone line. DSL speeds are generally higher than ISDN. DSL allows the use of high-bandwidth applications or multiple users to share the same connection to the Internet. In most cases, the copper wires already in your home or business are capable of carrying the signals needed for DSL communication.

There are limitations to DSL technology:

· DSL service is not available everywhere, and it works better and faster the closer the installation is to the telephone provider's central office (CO).

· In some cases, installed telephone lines will not qualify to carry all DSL signals.

· The voice information and data carried by DSL must be separated at the customer site. A device called a filter prevents data signals from interfering with voice signals.

Cable

Most homes that have cable television have the option to install high-speed Internet service using that same cable. Many cable companies offer telephone service as well.

Satellite

People who live in rural areas often use satellite broadband because they need a faster connection than dialup, and no other broadband connection is available. The cost of installation and the monthly service fees are generally much higher than those of DSL and cable. Heavy storm conditions can degrade the quality of the connection slowing down or even disconnecting the connection.

Cellular

Many types of wireless Internet services are available. The same companies that offer cellular service may offer Internet service. PC Card/ExpressBus, USB, or PCI and PCIe cards are used to connect a computer to the Internet. Service providers may offer wireless Internet service using microwave technology in limited areas.