Connecting
to the Internet
The
process used to connect to the Internet relies on the connection configuration
of a PC using either a dialup or network to connect. After the connection is
made, the process is the same and the same protocols are in use.
Dialup
connection
Dial-up
Networking has a built-in dialer that invokes the necessary commands to the
modem to dial the modems of the service provider and make a connection whenever
an application, such as a browser or an e-mail client, is opened. The speed of
a dialup connection is typically between 28.8 Kbps and 56 Kbps.
Remember
Dial-up networking uses PPP to send data packets over telephone
lines. PPP picks up a packet that has been created by one of the other network
protocols and which will be received by a remote PC running that same protocol.
PPP is merely the intermediary that carries the data packet over the telephone
line. If the packet begins the journey as a TCP/IP packet, it arrives at its
destination as a TCP/IP packet.
An
ISP typically assigns an IP address to PC though its NAS (network access
services), or modem banks, and RADIUS (Remote Authentication Dial-In User
Service) services, after a username and password combination is verified and
the user is authenticated.
If a
dialup connection will not connect, check the following areas:
l Remember Phone connection: Nearly
all modems use sound to enable the user to track the action of the connection
(handshake) as it is being made. The first of these sounds is the dial tone from
the phone line. If the modem is not connecting and you do not hear a dial tone,
there is a problem with the wall jack connection or the phone line itself.
Chances are that you will get an error message to the effect of no dial tone
anyway.
l Modem problems: If the modem cannot complete
the handshake with the other end, the modem might be configured incorrectly in
terms of its character length, start and stop bits, and speed.
l Protocols: Another common problem, especially for
new modems, is that TCP/IP or other protocols have not been properly
configured. Dialup connections typically require the PPP protocol. Verify that
the protocols are enabled and that the proper bindings are set for the protocols.
l Remote response: The NAS you are attempting
to connect to might be down or having problems. Call the ISP to check.
l Telephone company problems: If there is
sufficient static or crosstalk on the telephone line, it can cause the modem to
disconnect very soon after completing the connection or cause enough data
retransmissions that the line appears exceptionally slow.
Network
connection
If a
PC connects to the Internet through its LAN, its primary (or default) gateway
is the router on the LAN that is used to connect to the WAN (Internet). The
only real differences between establishing a dialup connection and a network
connection is that the network connection remains in place and does not require
a reconnection each time access is desired, and the user does not need to be
authenticated except for secure services, such as e-mail or VPN (virtual
private network).
IP
addressing
IP
addresses are four sets of numbers separated by periods (dots). An IP address
is 32 bits long with each of the four numbers 8 bits long. The highest possible
IP address is 255.255.255.255, because the highest value that can be
represented in 8 bits is 255. Each of the four numbers is called an octet,
which means a set of 8, and are referred to as the first, second, third, and
fourth octets. Sounds a little like a singing group--the Octets and their new
hit "Home, Home on the Domain."
IP
addresses can be assigned as a static IP address (a fixed PC location) or as a
dynamically assigned IP address (changeable). A static IP address is
permanently assigned to a node when it is added to the network. Static IP
addresses work as long as the network doesn't move, the NIC card is not
interchanged with other PCs, or the network is never reconfigured. If a network
will be reconfigured, however, it should use dynamically assigned IP addresses.
Each time the PC is booted, the Dynamic Host Configuration Protocol (DHCP)
server assigns it an IP address to use for that session. All versions of Windows
9 x and Windows NT, and Windows 2000 have built-in DHCP clients.
Sharing
an Internet connection
Internet
Connection Sharing (ICS) is a feature included in Windows 98 SE and Windows
2000 Professional that allows home and small office users to share a single
Internet connection. The type of connection isn't important, ICS assumes a
network to be present and isn't fussy about the type of network or the media
used.
ICS
builds a type of LAN with one PC serving as the network gateway. The other PCs
on the network use the gateway PC to connect to the Internet. The requirements
are that each PC be connected to the gateway via a network connection and that
a single modem, proxy server, DSL, ISDN, or other Internet connection line
serves the entire network.
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