Getting on the Internet

Internet Service ProvidersTransport Media

Sending Information Back & Forth

Internet Service Providers (ISP)

• Internet Service Providers (ISP) provide you with a connection between your computer and the Internet

• ISP provide varied Internet services (access to the WWW, email, listservs, etc.

• Depending on the service, you are usually charged either by the month or by the hour

So who is your ISP?

There are many ISP out there

• The top 3 ISP are*:1. AT&T with 12.9 subscribers2. Comcast with 12.1 million subscribers3. AOL with 12.0 million subscribers

• Some other ISPs include, NetZero, Earthlink, Juno, etc.

• Many colleges serve as an ISP, MCCC provides access to the WWW (email for faculty & staffat present).

• Let’s go to http://www.thelist.com/ and see some of what else is available.

*New York Times, May 3, 2007

Transport Media

• Transport medium is the physical connection which connects your computer to the internet.

• The Internet backbone consists of high speed fiber optic cables & copper transmission lines.

• This physical connection determines the speed and bandwidth capabilities of your Internet connection.

Using Telephone Lines

• Home connection using phone lines or is plain old telephone service (POTS) is still common.

• Modulators and demodulators (modems) send and receive digital information over analog phone lines

• Common modem speeds 28.8 Kbps & 56 Kbps

Kbps = kilobytes per second

Telephone Modem

Follow the signal to see how modems work by modulating the computer’s digital signal into an analog signal that can be transmitted over telephone lines to your ISP, where the signal is demodulated.

Ethernet

• Fast Ethernet network speeds led to growth of local area networks (LANs)– LANs transmit data at 10 megabits per second

(Mbps)

• Ethernet speeds are increasing– Twisted-pair telephone lines are 10/100BaseT

(100 megabits/second)– Fiber optic speeds are 10 gigabits/second (10

Gbps) or 10 billion bits per second

ISDN

• Integrated Services Digital Network (ISDN) allows for digital transmission of data over regular phone lines.

• ISDN carries both voice and data and supports real-time video conferencing

• ISDNs are being superseded by Digital Subscriber Lines (DSL)

DSL

• DSL means Digital Subscriber Line– Broadband connection over telephone lines– DSL is available to over 75% of United States

• There are two kinds of DSL– Synchronous DSL (SDSL) uses same speed for

all transmissions– Asynchronous DSL (ADSL) uses a higher rate

for downloads than uploads

ADSL

• Reduces the DSL cost.• More common in home applications • Typical users download more than

they upload (e.g. movies)• ADSL can use the same line for

simultaneous voice and data transmission while SDSL cannot

Cable Modems

• Cable modems connect PCs to TV cables using both Ethernet and television signals

• The term broadband refers to these connections that carry multiple channels over a single cable

• Speeds can vary depending on the number of simultaneous users on the cable’s network

Satellite

• If cable or DSL is not available, satellite Internet service is good if user has a view of the southern sky– Bad weather can impact speeds

• Satellite features– Typical speeds are 500 Kbps downstream and

150 Kbps upstream – Only one computer can be used per

subscription: DSL vendors allow more

Transmission Control Protocol (TCP)

• Recall that TCP governs how information gets transmitted in packets over the Internet– TCP divides information into packets– TCP routes data to destinations– TCP re-assembles the information

• TCP/IP are built in to the Windows and Macintosh operating systems

Comparing the Ways to Connect

Direct Connections

• An Internet connection that is always on is a direct connection– Dial-up modems are not direct connections

• Direct connections are– Ethernet– ISDN– Cable modem– DSL– Satellite

Let’s see how fast our connection is

Go to:http://www.bandwidthplace.com/

speedtest/