This
explanation is, admittedly, simplified but a good overview.
The
Internet is a "distributed" (loose) network ... this means thousands
of independent networks, companies, government and state agencies, organizations
and corporations are cooperating together to direct Internet traffic and
pass information. Some companies build very high-capacity lines (T1 or
greater), collectively called "a backbone", which transmits
enormous amounts of Internet traffic. Their customers are Internet Service
Providers ("ISP") who provide Internet access to you and me
(it is not unusual for a big ISP to build their own backbone).
A
variety of groups guide the Internet's growth by establishing standards
and protocols such as the Internet Activity Board and the National Science
Foundation. The World Wide Web Consortium developes standards for the
part of the Internet.
Information
travels across the Internet in small data packets - your file/email is
broken into hundreds of pieces of information (data packets). This is
because one main intent of the Internet was for the military to ensure
it could get the bulk of data received at its destination even if one
of its routing/forwarding points is destroyed. The TCP/IP protocol
(transmission control protocol/Internet protocol) was developed to handle
these packets. The TCP part inserts a header in each packet containing
the destination address and a reassemble number (checksum) then
adds instructions how to put the pieces back together at the destination.
These
packets are passed along the Internet in IP envelopes through routers.
Each router reads the header, examines traffic on its network and finds
the quickest way to pass the packet on to its next router (or destination).
Once the packets reach their destination, TCP kicks in again and reassembles
them according to checksum number (in the header).
Because
the Internet is hundreds of independent networks; and because one packet
of information can pass through dozens of routers, there is no way to
totally disable the Internet. To safeguard itself, each network/company
will have redundant (back up) systems which ensure that no one problem
will totally disable it.
Common
Connection Lines
Dial-Up
phone modem connections do not require any special wiring - it is
delivered over existing phone lines. Digital signals from your computer
are translated into analog signals and sent over the phone line. These
analog signals are demodulated back into digital information at the destination.
Dial-up connects are limited in that they can only perform one job at
a time: talk, send data or receive data. Internet access is via sessions,
online/offline.
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ISDN
is also a dial-up service with lines offer higher access speeds than modems
and are always on. These lines offer access speeds of 128 Kbps.
Digital
Subscriber Line/cable ("DSL") provides high speed business-class
Internet access. It is an upgrade from dial-ups because they: a) don't
convert signals like a dial-up so transmission is at a higher speed; and
b) they offer more capacity for simultaneous data exchange (in/out) and
talk. Its drawbacks are: it is a "party line" of many subscribers
so it is not considered tightly secure; and it is not widely available
because users and providers must be relatively close to each other.
Above
ISDN are dedicated (always on) high bandwidth lines: T1 lines carries
data at 1.544 Mbps; higher-speed T3 lines carry data at 44.746Mbps.
Be
a savvy Internet consumer:
always ask for references, written quotes and guarantees
where appropriate. do not release confidential information if you are unsure
whether the site is secure. and always take time to read any disclaimer for terms
and conditions.©1996-2008The
Business Colony