Introduction
One of the greatest things about the Internet is that nobody really
owns it. It is a global collection of networks, both big and small.
These networks connect together in many different ways to form the
single entity that we know as the Internet. In fact, the very name
comes from this idea of interconnected networks.
In this module, you will learn about the basic underlying structure
of the Internet so you can understand the actual mechanics of how
all of these computers connect to each other. But first, we need to
discuss some important keywords and fundamental concepts.
Transmission Control Protocol / Internet Protocol
TCP/IP is the technology used to connect computers across the
Internet and allow them to communicate. TCP/IP is the de facto
standard for communicating over the Internet.
IP Addressing
In order to reach the Internet, you need to have an address where
other computers may also reach you. Just as if you wanted to receive
a package from FedEx, you would need a physical address before you
could do so. Every computer on the Internet has a unique identifying
number called an IP Address. By convention, it is expressed as four
decimal numbers separated by periods, as seen below.
Example:
216.27.61.137
IP Addresses range from 0.0.0.0 to 255.255.255.255, for a total of
about 4.3 billion possible combinations.
The DHCP Server
The Dynamic Host Configuration Protocol (DHCP) is a server
responsible for assigning dynamic IP addresses to new computers that
are connecting to the Internet through them. With dynamic
addressing, a device can have a different IP address every time it
connects to the network. In some systems, the device's IP address
can even change while it is still connected. DHCP also supports a
mix of static and dynamic IP addresses. A static IP address means it
never changes while a dynamic IP address can and will change.
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Dynamic addressing simplifies network
administration because the software keeps track of IP
addresses rather than requiring an administrator to
manage the task. This means that a new computer can be
added to a network without the hassle of manually
assigning it a unique IP address. Many ISPs use dynamic
IP addressing for dial-up users.
Static addressing means network administrators are
required to specify an IP address for their computer
manually before they are allowed to connect to the
internet. This is a one-time configuration that is meant
to last. Some ISPs use static IP addressing for cable
modem users.
The DNS Server
The Domain Name Service (DNS) is a server that
translates domain names into IP addresses. Most people
prefer to use domain names like Google.com over an IP
address because they are easier to remember. However, in
order to connect to another computer on the Internet,
you need to know the other computers IP address.
Therefore, every time you use a domain name, a DNS
service must translate it into an IP address for you.
For example, the domain name http://www.google.com/
might translate into http://216.239.37.99/. You could
type an IP Address in your browser in order to bypass
the DNS server and connect directly to another computer.
Think of it as though you wanted to call Pizza Hut but
you didnt know the phone number. A DNS server would be
a phone book with which you could look up the phone
number. The DNS really is just like a gigantic phone
book for the Internet.
Of course, if you already had these numbers memorized,
you wouldnt really need the phone book or a DNS server
at all. If a DNS server goes down you can enter an IP
address into the customers browser to access a website.
If the website then appears, it is due to a DNS failure. |
Most ISPs have more than one DNS server in order to have a backup.
An added benefit is also if one DNS server doesn't know how to
translate a particular domain name, it asks another one, and so on,
until the correct IP address is returned.
The Gateway
The Gateway is a bridge between networks. In homes, the gateway is
the ISP that connects the user to the internet.
What is Dial-Up-Networking
Dial-Up-Networking allows your computer to use TCP/IP with a dial up
connection. A network connection and dial up connection are similar
but not identical. In the diagram below there are five different
items that are necessary to connect and browse the web with a dial
up connection. If the dialup adapter and modem were replaced with a
network card then it would be a network connection.
Browser or Application: End user programs like Internet Explorer,
Netscape, Outlook
Winsock.dll: Serves as the bridge between Windows networking and
the application
TCP/IP adapter: Offers Windows standardized access to TCP/IP
Dialup adapter: Allows Windows to treat DUN as any other standard
NIC
Modem: The hardware component that links to computers together
through an analog phone line
Communication Standards
Modems must negotiate with each other to find a common communication
standard. This is done so that they can communicate with the same
speed, error correction and data compression. There are different
standards that a modem can communicate in. The newest standard is
V.92 while the previous standard is V.90.
Among communication standards there is also a data compression
standard. The older standard is V.42bis while the new is V.44. V.44
offers a higher compression ratio. A higher compression ratio means
that more data can be downloaded in the same amount of time. For
most users, data throughput will be increased by 20 to 60%.
Additional features of V.92
Quick Connect: Learns phone line characteristics to lower the time
required to "Handshake".
Modem On Hold: Place a connection on hold to answer an incoming
call.
o Modem On Hold has specific requirements for it to function and those
are as follows: ISP must support it, customer has call waiting,
Modem On Hold software.
PCM Upstream: Boosts Uploading from client to server up to 48Kbps.
Smartlink Vs. Connexant
Smartlink and Connexant are the two primary modems that are shipping
with eMachines computers. The main differences between Connexant and
Smartlink are the software that comes with them and the standards
they support.
Connexant
Some Connexant modems will be V.92 while others will be V.90.
Information regarding the standard that the modem uses can be looked
up in eMacInfo2. Connexant modems do not come with additional
software necessary for Modem On Hold to function.
Smartlink
This type of modem will show in Device Manager as 56Kbps Internal
Modem. A second way to identify a system with this type of modem is
check eMacInfo2 under the modem category. Modem helper is software
that can be used to trouble shoot a Smartlink modem much more
efficiently than other types of modems. eMachines asks that we use
this software in all applicable situations.
The modem helper is the best method to test a Smartlink, and should
be used when troubleshooting any Smartlink Modem. Using
HyperTerminal to test a Smartlink is not as comprehensive of a test
and is a incorrect usage your tools, and you will be marked down on
your QA score.
Modem helper can be accessed through Start →
Control Panel → Switch to classic view
→ Modem Settings.
Card Test: Tests if the card is physically present and the drivers
are installed correctly.
Line Detection: Tests if a line is plugged in.
Dial Tone Detection: Checks for a dial tone.
Dialing Test: Dials the number from the top and attempts to
establish a connection.
Result Code: Displays a code detailing the results of the test.
Accurate notes are important for billing and reporting. eMachines
has asked for a uniform method of logging. All Smartlink calls
should include the phrase ModemHelper Result
Code: FF03101+0.0. Reports will be run to evaluate the
effectiveness of the Modem Helper.
Note: There is no space between Modem and helper. The result code
changes depending on what Modem Helper detects as the problem.
Modem Helper can be used to troubleshoot:
Port errors (Port Busy or in use)
No Dial tone
Dialing Errors
Server not responding
It would not be used for errors such as invalid username and
password. There is a complete walkthrough of Modem Helper and the
software reinstalling procedure for Smartlink modems and that can be
found at Troubleshooting →
Troubleshooting → Smartlink Modem Center.
EmacID# 70126.
Putting it all Together
As you can see, there are several important outside elements that
could potentially cause a problem for a customer trying to connect
to the internet. The first goal is to determine whether or not the
problem has to do with the computer or with the ISP.
If it is a problem with the computer some of the most basic
troubleshooting steps are: check connections, reinstall the
connection device drivers (modem or network card), and ultimately
EURP a replacement connection device. Otherwise, if it is a problem
with the connection, you will simply refer these customers to their
Internet Service Provider.
Always remember that we do not support networking. We are only
interested in determining if the computer is working properly. If
the customer wants to know how to configure their home network, you
can refer them to Help and Support or Priority One Support for
assistance.
Network Troubleshooting
There are a few commands you can use when troubleshooting networks
that you will need to be familiar with. These commands are to be
typed at the command prompt, which can be accessed from the START
menu:
Click on START
Click on Run
Type in command without the quotes
Click on OK
IPCONFIG
IPCONFIG is one of the most useful utilities for troubleshooting
network issues. IPCONFIG can be used to show your current TCP/IP
information including your IP address, DNS server addresses, DHCP
server address, Gateway address, adapter type and so on.
The DHCP server usually assigns the TCP/IP information. Running
ipconfig will allow you to determine if the customer has any of the
above information. If all the above information is present we can
rule out the network card itself having a problem. The reason we can
rule it out is if the network card wasnt working at all, the ISP
would not be able to send any of the information to the computer.
When you use this command, ask the customers to read the screen and
write down the addresses associated with each of the following: IP
Address, Default Gateway, DHCP Server, DNS Servers. Later on you
will PING these addresses to determine if an Internet connection is
available.
Command Usage:
IPCONFIG /ALL
169.254.X.X is an address that Windows will assign to a network card
if no DHCP server is found. If the customer has this IP address,
make sure the network card is plugged in and that the activity light
is on.
PING
If you are having connectivity problems, you can use the PING
command to check the destination IP address you want to reach and
record the results. PING sends a small packet of information to a
destination IP address and listens for a reply. The PING command
displays whether the destination responded and how long it took to
receive a reply. If there is an error in the delivery to the
destination, the PING command displays an error message.
You can use the PING command to:
Ping your computer to determine that TCP/IP is functioning.
Ping your Gateway to determine that the ISP is functioning.
Ping beyond your ISP to determine that you are getting to the
Internet.
Command Usage:
PING 216.239.37.99
If there are four replies, then your PING was successful and it
should be working.
If there are a few replies, then you are experiencing data loss. Ask
the customer to shorten the length of their phone or network cable
and commonly power cycle the DSL modem or cable modem to reset them
If there are zero replies, then your PING failed.
NETSH
With the NetShell utility, you can reset the TCP/IP stack back to
the same state as when the operating system was first installed. Use
this when the TCP/IP stack appears to be having problems.
When this command is executed, it rewrites registry keys that are
used by the TCP/IP stack to achieve the same result as the removal
and the reinstallation of the protocol.
Command Usage:
netsh int ip reset
Software Configuration
Firewalls
A firewall protects your PC from intrusion. It checks incoming
requests and ensures that a valid request was sent from your PC
before it will accept the packets (a packet is a piece of incoming
information). If the incoming packets are not allowed by a rule or
if they were not a valid request the firewall will block the packets
from being received.
TCP/IP works on ports. For example, port 80 handles http traffic.
This is the port that allows you to view web pages. If I set up a
rule blocking traffic on port 80 you would be unable to browse web
pages, but still be able to send ping requests.
See EmacID# 70079 in eMacInfo2 for more information.
WINSOCK.DLL
WINSOCK.DLL is a dynamically-linked library that provides a common
application programming interface (API) for developers of network
applications that use the Transmission Control Protocol/Internet
Protocol (TCP/IP) stack. In short, this file allows different
communications programs to talk with windows.
See article 70088 in eMacInfo2 for more information.
HyperTerminal
HyperTerminal is a terminal emulation program. It allows you to talk
directly to the modem without using the ISP software, dialing rules
or dial-up networking. If a modem can dial out and connect to a BBS
(Bulletin Board System) the hardware is functional and you should
start troubleshooting software at that point. Check under OS tools
and Utilities for more information.
See EmacID# 70058 in eMacInfo2 for more information.
Situations to Talk About
Customer can connect to the internet with their dialup modem, but
can not view web pages.
Customer receives an error 680 whenever they try to connect.
Customer has a broadband connection and cannot view web pages.
Customer is connecting at a slow rate and wants you to fix it
Customer has a wireless card and is having range issues.
When to Refer a Customer to their ISP
First you must prove to the customer that their modem and/or network
card is functioning properly. Afterward, if problems persist, you
may refer these customers to their Internet Service Provider for
additional support suggestions.
Outside Resources
How Ethernet Works
http://computer.howstuffworks.com/ethernet.htm
How Home Networking Work
http://computer.howstuffworks.com/home-network.htm
Where are all the Internet domain names registered and
maintained?
http://computer.howstuffworks.com/question422.htm
What is an IP Address?
http://computer.howstuffworks.com/question549.htm
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