Introduction
Most of the world still uses a standard modem to connect to the
Internet. However, that is quickly changing in favor of new
high-speed technology. eMachines is now shipping both 56Kbps modems
and 10/100 network cards in all of its systems. The system will be
ready for whichever method the customer decides to connect to the
internet. Currently, internet connectivity is one of our highest
call drivers. In this module, we'll teach you which components are
involved in the process and how far you'll go to troubleshoot them.
Modems
Short for modulator-demodulator. A modem is a device that enables a
computer to transmit binary data in the form of sound. Computers
work with numbers, so to get analog sound from a medium such as a
telephone wire into our computers, it is necessary to devise a
mechanism to convert sound to numbers and back again from numbers to
sound. A modem converts between these two forms.
The hardware that does the job of converting a sound into a number
is an analog-to-digital converter (ADC). Similarly, numbers can be
converted back into sound using a digital-to-analog converter (DAC).
56Kbps Dial-up Modems
The most common use of the word “modem” refers to a 56Kbps
dial-up modem. They convert digital information to sound that is
transmitted via telephone lines. Every eMachines computer has one
now; it is where you connect the telephone line to on the back of
your computer. Modems are also a disposable part, which we replace
if we need to.
Long ago, when modems were first invented, they were external
devices like cable/DSL modems are today.
High-Speed Cable/DSL Modems
Cable modems and DSL modems are designed to deliver upwards of
256Kbps access to the Internet. These convert digital information to
analog waveforms transmitted along coaxial cable or DSL telephone
lines; basically the same idea as a 56Kbps modem except on a wider
scale. We have a very limited scope of support with these devices
because they are not provided with any eMachines computer.
These are external third-party devices, which are usually purchased
or rented from the Internet Service Provider (ISP). In most cases,
we leave the troubleshooting of these up to the ISP who sold it to
the customer.
Cable/DSL modems connect to the computer most commonly via the
network card or sometimes via USB. It is possible that a DSL modem
could also be internal. From a support standpoint, we are
responsible to make sure that the network card and/or USB ports are
functioning properly before we may refer these customers to their
ISP.
Network Interface Cards (NIC)
Network cards provide a full-time, high-speed connection to a
network (such as the Internet). Often times they work together with
cable/DSL modems to provide Internet access as they have the ability
to transmit high amounts of data.
The network cards we are currently shipping are 10/100 network
cards. This indicates that the card is capable of 10Mb or 100Mb data
transfer rates. There are two lights on the network card:
• Green: Status / Activity
When this light is on or flashing, the network card is receiving
electrical signals.
• Amber: Speed
When this light is on, the network card is running at full speed
(100Mb)
Two Types of Cables
Currently there are two different types of cables to be used
depending on the type of network you are configuring. You should
already be familiar with the ordinary phone cable which is used for
a 56Kbps connection to the internet. There is a different kind of
cable used with cable/DSL modems. Sometimes people confuse the two,
but they are in fact different sizes.
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RJ-11
RJ-11 cabling is used with ordinary telephones and
56Kbps dial-up modems.
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RJ-45
RJ-45 cabling is used with network cards, cable modems,
and DSL modems.
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Crossover Cable
A crossover cable is a RJ-45 cable that has the specific job of
allowing one computer to connect directly to another. If a customer
is ever trying to connect one computer directly to another, with no
device in between such as a hub, without a crossover cable it will
not work. Chances are that if a customer doesn’t know what a
crossover cable is, then they don’t have one.
Routers vs. Hubs vs. Switches
Router
A device that forwards data packets along networks. A router is a
device that gives many options for networking. Routers have
extensive networking options and we do not support them in any type
of connection situation, with the exception of wireless. Routers are
located at large junction points and commonly where two or more
networks connect.
Hub
A hub passively serves as a conduit for the data, enabling data to
go from one device to another. So-called intelligent hubs include
additional features which allow an administrator to monitor the
traffic passing through the hub and to configure each port in the
hub. It allows more than one computer to be interconnected at the
same time.
Switch
A type of hub, called a switching hub, which reads the destination
address of each packet and then forwards the packet to the correct
port.
Wireless Networking
Wireless networking, also known as WiFi, converts digital data to
analog radio waves and vice-versa. The basic function is not too
different from that of an ordinary network. In fact, it even relies
on the same technology as a wired network.
Fortunately, all of this radio technology is hidden in a WiFi card
and is completely invisible. WiFi, in fact, is one of the easiest
technologies that you will ever use.
Wireless Access Points Vs. Wireless Routers
An access point is a device that takes a wired connection and turns
it into a wireless signal for any wireless card to pick up. Routers
are an access point and much more. Routers allow for, security,
configuration, and many other options that for troubleshooting
purposes we will never deal with. We only support the wireless card
seeing a router or access point and not the configuration of either.
Current Wireless Standards
Although more standards are probably on the way, currently there are
only three major standards in the market:
• 802.11a operates at 5 GHz and can handle up to 54 megabits
per second. This is not commonly used due to some problems with the
range that it operates.
This standard is only compatible with itself.
• 802.11b is the slowest and least expensive of the three.
802.11b transmits at 2.4 GHz and can handle up to 11 megabits per
second.
This standard is only compatible with itself.
• 802.11g is a mix of both worlds. It operates at 2.4Ghz
(giving it the cost advantage of 802.11b) but it has the 54 megabits
per second speed of 802.11a.
This standard is backward-compatible with 802.11b.
Note: Actual speeds will vary depending upon the distance from the
nearest access point and any electronic interference from other
devices.
eMachines currently ships 802.11g products based on the Broadcom
chipset. While it is important to be aware of the available security
for wireless, eMachines does not support its configuration for an
end user.
Wireless Networking Features
WEP (Wired Eqiuvalant Privacy)
WEP is a security protocol that can be 64, 128, or 256 bit
encryption. WEP is considered a weak encryption method.
IEEE 802.1X
802.1x is much stronger than WEP, but is not something most
end-users will use. It requires Authentication against a radius
server and is difficult to set up.
WiFi Protected Access (WPA)
WPA offers much stronger security and is intended as a replacement
for WEP. The access point the customers connect to have to support
WPA and an update from Microsoft needs to be applied to Windows XP
for it to work.
SSID Service Set ID
The SSID is the name of the access point the card is connecting to.
Most access points ship with an SSID of “Any” and any SSID can
connect to it.
Channels
There are 11 channels allowed by the FCC. Channels 1,6, and 11 are
the only channels that do not step on each other. Channel 11 can
conflict with microwaves and cell phones. If a customer is having
connectivity issues we can recommend that they change the channel on
their access point. Since 802.11b and 802.11g operate on the 2.4 GHz
frequency, a 2.4 GHz phone could cause interference. The same thing
can happen with a microwave or any other appliance that functions at
2.4 GHz. Changing the channels should alleviate these difficulties.
Outside Resources
How Modems Work
http://computer.howstuffworks.com/modem.htm
How Cable Modems Work
http://computer.howstuffworks.com/cable-modem.htm
How Home Networking Works
http://computer.howstuffworks.com/home-network.htm
How Wireless Internet Works
http://computer.howstuffworks.com/wireless-internet.htm
How WiFi Works
http://computer.howstuffworks.com/wireless-network.htm
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