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How the Internet
Works:
Part II - Get Connected
This article originally appeared in the January/February
2002 issue of Progressive Distributor. Copyright 2002.
This is the first in a series of articles
that explain basic Internet technology concepts in non-technical
terms for distributors.
by Akarin Weatherford
You often hear the word bandwidth during discussions
of interconnectivity. Ask someone to explain what bandwidth is and
how it relates to your company, and you’ll get an answer that brings
you to their level of confusion. Here’s a simple analogy to straighten
things out.
Think of bandwidth as the number of lanes on a
highway. The cars on the highway represent all the data you are
trying to move. If you have 100 cars, will a two-lane or a 10-lane
highway get them from Point A to Point B in the least amount of
time? The answer, of course, is the 10-lane highway. The wider the
highway (bandwidth), the quicker we can move more cars (data) from
Point A to Point B.
Bandwidth is usually measured in “bps,” or how
many “bits per second” we can push through the connection. Metric
modifiers like “Kilo” (K = 103) or “Mega” (M = 106) are often added
to help quantify the speed. So, 56 Kbps = 56,000 bps and 1.5 Mbps
= 1.5 million bps.
It’s pretty confusing sometimes to try to figure
out all the options available to you for connecting to the Internet.
We are going to touch on the most common connection options and
give you a heads up on speeds and general pricing.
Modem dial-up
Modem dial-up access is the most common and affordable
way to connect to the Internet. It is also one of the slowest methods
and usually connects only one PC at a time. Modems connect computers
to the Internet by performing a digital-to-analog conversion for
transmission onto the phone lines and vice versa on the receiving
end. Most modems support a maximum speed of 56 Kbps, but rarely
connect at that speed because of phone line limitations. A modem
also ties up your phone line, so you may need another line if you
want to receive calls simultaneously. Dial-up access is “on demand,”
so you have to proactively access the Internet. You can expect to
pay up to $20 a month for this service.
Cable access
Cable access is relatively new. It is one of the broadband technologies
opening high-speed Internet access anywhere cable television is
available. Cable access is a digital signal sent over the unused
channels on the existing cable TV in your home or office.
Using the highway analogy, cable TV has always
been a 10-lane highway. To give you 100 channels of TV programming,
cable TV used only about two of the 10 lanes. Internet access is
just one of the many services on the unused bandwidth. You can expect
speeds of 256 Kbps to 6 Mbps depending on the services offered by
the cable company.
Cable access is “always on,” meaning your phone
lines are available and you never have to do anything to connect
to the Internet. One drawback is that you share your connection
with everyone on your block who subscribes to the same service.
You basically share the cable company’s LAN (Local Area Network)
with other customers, which is why they don’t usually guarantee
the maximum speed you purchase. Therefore, at peak hours, the bandwidth
may become saturated (traffic jam on the highway), plus there are
security concerns about your neighbors “peeking in” on your data.
Cable access is available for home or office with prices starting
around $40 per month for home and around $80 per month for office.
DSL (Digital Subscriber Line)
DSL is a service offered by a phone company. It uses the existing
copper in your building to provide high-speed Internet access and
is a direct competitor with cable access. DSL uses digital signals
over phone lines but also gives you the ability to use analog phones
simultaneously with the addition of a small adapter box. DSL is
always on like cable and has varying speeds from 144 Kbps up to
1.5 Mbps. However, DSL is only available in metropolitan business
areas due to the special conditioning the phone company must do
to its lines and equipment behind the scenes. DSL is quickly becoming
more competitively priced with cable access. Prices range from $50
per month to $100 per month for basic services.
Integrated Services Digital Network (ISDN)
ISDN is the long-standing, digital voice and data service traditionally
made available to small businesses by phone companies. ISDN uses
regular phone lines but requires a network termination device in
your office to connect a limited number of ISDN devices (phones,
terminals, alarms, network devices, etc.). ISDN is sold in 64 Kbps
channels and is still an expensive alternative at about $60 per
channel per month.
Leased lines
Leased lines are the top dogs when it comes to Internet access.
The most common leased line is a T-1 (1.544 Mbps). A T-1 can be
broken up into smaller, more affordable fractions or multiplexed
with other T-1s to create a T-2 (6.3 Mbps), a T-3 (5 Mbps), a T-4
(274 Mbps), and so on. A T-1 is a digital signal that operates over
a standard, copper cable. The benefits of having a leased line are
in security and control. With a leased line, the full bandwidth
is dedicated to you directly from your office to the Internet. Also,
you have complete control over the use of that bandwidth. When hosting
Web sites and Web applications, this is the preferred method. Prices
range from $500 to $1,500 per month for T-1 connections depending
on selected service options.
Wireless
There are many options when it comes to connecting wirelessly
to the Internet. Offices use satellite, microwave or RF (radio frequency)
to get Internet connectivity in remote locations. There are new,
fixed wireless solutions coming on the horizon that will allow your
local ISP to directly compete with national Cable and DSL providers
by offering faster service at approzimately the same price. For
personal communication, individuals can use one of the many flavors
of analog or digital cellular connections. However, there is such
a broad array of technologies available and unique costs associated
with each that this topic deserves its own dedicated article. Just
understand for now that, in general, affordable mobile wireless
data rates are very slow — 14.4 Kbps to 33.6 Kbps (they claim higher
rates, but actual performance is more like dial-up at this speed)
and the cost is normal voice per-minute charges. At the other end
of the spectrum, a T-1 transponder on an Intelsat satellite will
cost you about $15,000 per month.
Why are some connections so slow and expensive?
If two computers in your office are networked together at 100 Mbps
(the most common office network speed), and it cost you under $100
at the office supply store to buy the parts to hook them together,
why does an ISP charge $1,000 a month for a T-1 (1.5 Mbps), which
is 10 times the cost at 1/15th the speed?
The basic reason is because of various limitations
on the technology. You see, a LAN has a known worst-case distance
between computers, usually covering up to a square mile. Because
of this assumption, all sorts of inexpensive hardware and software
methods can be used to boost accurate and blazingly fast performance.
When dealing with a WAN (Wide Area Network), the worst-case distance
between computers is unknown and specialized hardware and software
methods must be used to provide reliable connections.
Hooking up the plumbing
“You’re only as strong as your weakest link” applies to Internet
connections with a slight twist: “You’re only as fast as your slowest
connection.” Here’s an example.
Office A’s LAN is 100 Mbps and connects to the
Internet via a 256 Kbps ISDN connection. Office B’s LAN is 100 Mbps
and connects to the Internet via a 1.544 Mbps T-1. The fastest data
transfer rate between Office A and Office B is 256 Kbps because
that is the slowest connection in the chain. It is important to
identify and understand where the bottleneck in bandwidth exists.
You may not need to invest big dollars in the latest, greatest network
equipment if you can’t take advantage of its features because of
your network connection speed to the Internet.
Watch your "B" and "b’s"
Now you’re armed and dangerous with the basic knowledge of various
connection types and speeds to the Internet. Here’s one “gotcha”
that gets a lot of people, even your long-haired IT guys if they’re
not paying attention. There is a little math here, but if you get
this, you’ll keep from looking like a goof when it comes up.
Let’s say you just got that high-speed T-1 connection
in your office (remember, that’s 1.544 Mbps). You begin to download
a document off the Web from Yahoo!, which has a “fat pipe” on the
Internet (they have a whole lot of bandwidth). A little window pops
up showing your download progress and the download speed. You notice
the speed is 75 KBps and think to yourself, “75 K? I have 1,544
K (1.544 M) connecting me to big bad Yahoo!, so why is it downloading
so slow at 1/20th the speed of my T-1?”
Actually, it’s not. Pay attention to the size of
that “B.” Notice that we have been talking about connection speeds
in “bps” or “bits per second.” The download box you see uses “Bps”
or “Bytes per second.” For anyone geeky enough, you know there are
eight bits in one Byte, and 1 Kilobyte = 210 Bytes or 1,024 Bytes
(because of the binary to decimal conversion). For the rest of the
normal world, we’ll just say there’s a crude and rough 10X difference
between a bit (b) and a Byte (B). So, doing a quick conversion on
the above statement, 75 KBps converts to 750 bps, which is about
half your full T-1 connection speed (the exact value is 614.4 KB).
So, in reality, you’re moving really fast!
This article originally appeared in the March/April
2002 issue of Progressive Distributor. Copyright 2002.
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