Digital Subscriber Line
Practical Guide To
DSL
FAQ
Can I talk on the phone and surf the Internet at the same time?
Can I share the DSL connection between several computers?
Are there any special requirements for the DSL modem?
Is a DSL modem wall-mountable?
Is a DSL modem rack-mountable?
Can I talk on the phone and surf the Internet at the same time?
Short
Answer: Yes.
Long Answer: If your DSL is on a separate pair of wires, then
your phone service is never affected in the least. If your DSL
is on the same pair of wires as the telephone, you can still
talk on the phone while you're connected to the internet. The
filters that your phone company sends you will make sure that
your telephone sounds as clear as usual.
Can I share the DSL connection between several computers?
Short
Answer: Yes.
Long Answer: Depending on the type of modem that you have, you
will either be able to just plug several network cables into
the back of the modem (the Netopia 7000 series, for example,
has a built-in 8-port ethernet hub), use an external ethernet
hub or have to set up a proxy server. If you have a router (such
as the Netopia 7000 series) then your router will typical perform
network address translation and allocate fake IP addresses on
the inside. You will typically be limited to about 255 computers
connected this way, though there may be physical reasons why
you can only connect fewer machines. If you have a bridge (such
as the Efficient Networks SpeedStream 5000 series) then you have
to set up a proxy server or some type of internet connection
sharing software on one computer, and connect to the internet
that way.
Are there any special requirements for the DSL modem?
Short
Answer: No.
Long Answer: The DSL modem is a piece of equipment that you typically
put somewhere out of the way. Under normal circumstances you
should never have to touch it once your line is installed. This
unit will always be on, even if your computer is off. All that
is required to connect a DSL modem is a power plug and two wires
(most modems ship with just one wire, so you will need to have
an ethernet cable).
Short
Answer: Depends.
Long Answer: DSL reliability is rather iffy. You can be lucky
enough to install it and never have a problem again. Then again,
you might be unlucky enough to spend time on the phone with technical
support every week. My personal experience with the service (I
have had DSL for over a year) has been mostly an uphill battle.
The service is great when it works, but I have called support
more times than I care to count. If internet connectivity is
mission-critical, then I suggest you either have a dial-up account
for backup (some DSL providers will give you dial-up access free
of charge, but then if the problem is on their end, that may
not help you in the least) or spend the extra money for a T1
line.
Short
Answer: Fast.
Long Answer: The fastest a regular dial-up modem can go is 56,000
bits/second (FYI: there are 8 bits in a byte). The slowest a
DSL connection will usually go is 128,000 bits/second (you do
the math). The fastest a DSL connection can go is about 6,000,000
bits/second. Typical home DSL connections will be 1,500,000 bits/second
download and 384,000 bits/second upload speed or 608,000 bits/second
download and 128,000 bits/second upload. How fast you can go
depends on a) how many feet of wire there is between you and
your phone company's office (Covad claims to offer 144,000 bits/second
DSL service at almost 8 miles of wire) b) whether you choose
ADSL or SDSL and c) how much you're willing to spend.
Short answer:
ADSL and SDSL differ in whether the speed is the same downloading and
uploading.
Long answer: ADSL (asymmetrical digital subscriber line) has
a higher download speed at the cost of a slower upload speed.
ADSL is what is usually found in homes. SDSL (symmetrical digital
subscriber line) has the same speed both ways. SDSL is usually
found in small offices and home offices.
Short
answer: Yes.
Long Answer: In terms of safety from hackers, viruses and other
problems DSL is almost as safe as a dial-up connection. I say
almost, because the major difference is that DSL is always on.
In a dial-up situation, a hacker typically doesn't have enough
time to target your computer, but you're only connected for a
few hours at a time and because your computer has a different
IP address each time you dial your ISP. In a DSL situation, you
are connected to the internet whenever your computer is on, whether
you're actively browsing around or not. With DSL you will also
typically be assigned an IP address that belongs to you and only
you in the entire world. This makes your computer an easier target
for hackers. You should always take security precautions when
connecting to the internet, whether by dial-up or DSL.
Short
Answer: Roughly the size of a hard-cover book. (see pictures)
Long Answer: The Netopia 7000 series is about 9" wide by
8.5" deep by 2" tall. The Efficient Networks SpeedStream
5000 series is about 5" wide by 7" deep by 1.5"
tall.
Is a DSL modem wall-mountable?
Short
Answer: Depends.
Long Answer: The Netopia 7000 series is wall mountable. The SpeedStream
5000 series does not come wall mountable, but if you're handy,
you could probably work something out.
Is a DSL modem rack-mountable?
Short
Answer: No.
Long Answer: The modems in the Netopia 7000 series and the SpeedStream
5000 series are not rack-mountable. If you're aware of any DSL
modems that are, please let me know.
This guide was written by Sergey Polak, a computer programmer and network engineer. He has a BS in Computer Science, is a Microsoft Certified Professional and has over 9 years experience in the field.
