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Networking Basics |
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A network is a group of
computers, printers, and other devices that are connected together with
cables. Information travels over the cables, allowing network users to
exchange documents & data with each other, print to the same printers,
and generally share any hardware or software that is connected to the
network. Each computer, printer, or other peripheral device that is connected
to the network is called a node. Networks can have tens, thousands, or
even millions of nodes. Like most things, networks are are assembled according to certain rules. Cabling, for
example, has to be a certain length, each cabling strand can only support a
certain amount of network traffic, etc. The rules that govern how a network
is set up is called its topology. The most popular topology in use
today is called Ethernet, which consists of computers and peripherals
cabled together in specific ways. Ethernet is relatively inexpensive, easy to
set up and use, and very, very fast. Ethernet networks are
categorized by how fast they can move information. Speed is expressed in megabits
per second (or Mbps), where one "bit" is equal to 1/8th
of a character, letter, or number. There are currently two Ethernet speed
categories. Standard Ethernet operates at a fast 10Mbps, which is
quick enough for most networking tasks. Fast Ethernet, by contrast,
races along at a blistering 100Mbps, making it ideal for desktop video,
multimedia, and other speed-hungry applications. The new technology behind
Fast Ethernet, which was introduced in the beginning of 1995, is not readily
compatible with standard Ethernet. Making the two "talk" with each
other requires special equipment (see switching hub below) and
some knowledge of internetworking. If you're building your first network,
decide whether to go with standard or Fast Ethernet before you begin shopping
around for network hardware and software. Unless you plan on using video,
multimedia, or heavy graphics software, plan on using standard Ethernet. For
more information on standard and Fast Ethernet, Cabling Basics The two most popular types of
network cabling are twisted-pair (also known as 10BaseT) and thin
coax (also known as 10Base2). 10BaseT cabling looks like ordinary
telephone wire, except that it has 8 wires inside instead of 4. Thin coax
looks like the copper coaxial cabling that's often used to connect a VCR to a
TV set. Which type of cabling
is best for you? Thin coax and 10BaseT can both be used exclusively or
together, depending on the type of network that you're Network Adapters A network computer is connected
to the network cabling with a network interface card, (also called a
"NIC", "nick", or network adapter).
Some NICs are installed inside of a computer: the
PC is opened up and a network card is plugged directly into one of the computer's
internal expansion slots. If a PC lacks expansion slots
(which is true with portable PCs), special network adapters are used. A PCMCIA
network adapter connects a PC to a network if the PC has a credit card-sized
PCMCIA expansion slot, while a pocket adapter connects a PC to a network
through its printer port. Hubs The last piece of the
networking puzzle is called a hub. A
hub is a box that is used to gather groups of PCs together at a central
location with 10BaseT cabling. If you're networking a small group of
computers together, you may be able to get Like network cards, hubs are
available in both standard (10Mbps) and Fast Ethernet (100Mbps) versions. If you're new to networking,
take a look at our new Network Starter
Kits. They're just right for building your first network at home
or in the office! |
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Client Server vs. Peer-to-Peer |
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Every
network requires special software to control the flow of information between
users. A Network Operating System, or NOS, is installed onto
each PC that requires network access. The NOS is like a traffic cop that
monitors the exchange and flow of files, electronic mail, and other network
information. Network Operating Systems are
usually classified according to whether they are peer-to-peer or client-server
NOSs. Peer-to-peer NOSs
like Windows 95 and Windows for Workgroups are best for home & small
office use--they're great for sharing applications, data, printers, and other
localized resources across a handful of PCs. Client-server NOSs like Windows NT and NetWare are ideal for
large-scale organizations that require fast network access for video,
publishing, multimedia, spreadsheet, database, and accounting operations. Peer-to-Peer
Networks A peer-to-peer network allows
two or more PCs to pool their resources together. Individual resources like
disk drives, CD-ROM drives, and even printers are transformed into shared,
collective resources that are accessible from every PC. Unlike client-server networks,
where network information is stored on a centralized file server PC and made
available to tens, hundreds, or thousands client PCs, the information stored
across peer-to-peer networks is uniquely decentralized. Because peer-to-peer
PCs have their own hard disk drives that are accessible by all computers,
each PC A peer-to-peer network can be
built with either 10BaseT cabling and a hub or with a thin coax
backbone. 10BaseT is best for small workgroups of 16 or fewer users that
don't span long distances, or for workgroups that have one or more portable
computers that may be disconnected from the network from time to time. After the networking hardware
has been installed, a peer-to-peer network software package must be installed
onto all of the PCs. Such a package allows information to be transferred back
and forth between the PCs, hard disks, and other devices when users request
it. Popular peer-to-peer NOS software includes Windows 95, Windows for
Workgroups, Artisoft LANtastic, and NetWare Lite. Most NOSs
allow each peer-to-peer user to determine which resources will be available
for use by other users. Specific hard & floppy disk drives, directories
or files, printers, and other resources can be attached or detached from the
network via software. When one user's disk has been configured so that it is
"sharable", it will usually appear as a new drive to the other
users. In other words, if user A has an A and C drive on his
computer, and user B configures his entire C drive as sharable, user A
will suddenly have an A, C, and D drive (user A's D
drive is actually user B's C drive). Directories work in a similar
fashion. If user A has an A & C drive, and user B
configures his "C:\WINDOWS" and "C:\DOS" directories as
sharable, user A may suddenly have an A, C, D, and E drive (user
A's D is user B's C:\WINDOWS, and E is user B's C:\DOS). Did
you get all of that? Because drives can be easily
shared between peer-to-peer PCs, applications only need to be installed on
one computer--not two or three. If users have one copy of Microsoft Word, for
example, it can be installed on user A's computer--and still used by user B. The advantages of peer-to-peer
over client-server NOSs include:
Client-Server Networks In a client-server environment like Windows NT or Novell
NetWare, files are stored on a centralized, high speed file server
PC that is made available to client PCs. Network access speeds are
usually faster than those found on peer-to-peer networks, which is reasonable
given the vast numbers of clients that this architecture can support. Nearly
all network services like printing and electronic mail are routed through the
file server, which allows networking tasks to be tracked. Inefficient network
segments can be reworked to make them faster, and users' activities can be
closely monitored. Public data and applications are stored on the file
server, where they are run from client PCs' locations, which makes upgrading
software a simple task--network administrators can simply upgrade the
applications stored on the file server, rather than having to physically
upgrade each client PC. In the client-server diagram below, the client PCs are shown to
be separate and subordinate to the file server. The clients' primary
applications and files are stored in a common location. File servers are
often set up so that each user on the Network Printing In client-server networks, network printing is normally handled
by a print server,
a small box with at least two connectors: one for a printer, and another that
attaches directly to the network cabling. Some print servers have more than
two ports--they may, for example, support 2, 3, or 4 printers simultaneously.
When a user sends a print job, it travels over the network cabling to the
file server where it is stored. When the print server senses that the job is
waiting, it moves it from the file server to its attached printer. When the
job is finished, the print server returns a result message to the file
server, indicating that the process is complete. In the diagram below, the laptop client PC sends a job to the
file server. The file server, in turn, forwards the job to the Print Servers are available for both client-server and
peer-to-peer networks. They're incredibly convenient because they let you put
a printer anywhere along your network even if there isn't a computer nearby.
However, users often opt not to use a print-server with their peer-to-peer
network. Why? Because every computer's resources are available to everyone on
the network, Sally can print a job on John's printer--just as if In this example, the printer is attached to the computer on the
right. When the PC on the left sends a job, it "thinks" that it is
printing to a printer of its own. In actuality, the job travels over the
network cables to the PC on the right, which stores and prints the job in the
background. The user at the PC with the printer is never interrupted while
his computer processes and prints the job transparently. Remote Access & Modem Sharing When a client-server network needs a gateway to the world, the
network administrator usually installs a remote-node server, which serves up
two functions: remote access and modem sharing. Most remote-node servers
attach directly to the network cabling; they provide a bridge between the
network, a modem, and a telephone line. Remote access allows users to dial into their home networks from anywhere in
the world. Once a connection has been established over ordinary phone lines
by modem, users can access any programs or data on the network just as if
they were seated at one of its local workstations. Some remote access servers
only provide access to a file server's disk drives. Others can provide access
to both the file server and direct access to any PC's hard disk on the
network. This saves time because it allows a remote user to communicate
directly with any network user without having to go through the file server. Modem sharing lets local network users dial out from their individual network
computers to access the Internet, bulletin boards, America On-Line, and more.
After firing up their favorite communications software, local users establish
a link with the remote-node server over the network, which opens up an
outgoing telephone line. Users' individual PCs don't need modems, which is a
big money saver--only a single modem & phone line are required for tens
or hundreds of users. In the case of peer-to-peer networks, by contrast,
every PC requires its own modem for access to the outside world. |
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All About Cabling |
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All About Cabling The two most popular types of
network cabling are twisted-pair (also known as 10BaseT) and thin
coax (also known as 10Base2). 10BaseT cabling looks like 10BaseT Cabling When 10BaseT cabling is used, a
strand of cabling is inserted between each computer and a hub. If you have 5
computers, you'll need 5 cables. Each cable A 10BaseT hub is basically a
box with a row of 10BaseT jacks. Most hubs have 5, 8, 12, or 16 jacks, but
some may have more. Most hubs also have an uplink port, which is a
special 10BaseT or thin coax port that allows the hub to be connected to
either (1) other hubs, or (2) a thin coax backbone (see below for
information on backbones). By uplinking
multiple hubs together, you can add additional computers to your network
whenever you need to. 10BaseT cabling is available in
different grades or categories. Some grades, or "cats", are
required for Fast Ethernet networks, while others are perfectly acceptable
for standard 10Mbps networks--and less expensive, too. About 85% of the
networks in the U.S. use standard unshielded twisted-pair (UTP) Category 5
10BaseT cabling because it offers a performance advantage over lower grades.
If you are using a 10Mbps network, category 3 is fine. If you plan on
building a Fast Ethernet network at some time in the future, it's best to
install Category 5 cabling. 10BaseT Category What It's Used For------------------------------------------------------- 5 Fast Ethernet (and everything below) 4 Networks other than Ethernet 3 10Mbps 10BaseT 2 Alarms, telephone voice lines 1 Unknown (not rated for anything specific)
If possible, decide whether you'll be using standard Ethernet or
Fast Ethernet technology before you begin building your network. If you're
not sure which technology you'll eventually use, choose to install Category 5
cabling. Remember, Fast Ethernet network adapters and hubs are not directly
compatible with each other. It is possible to have both 10Mbps and 100Mbps
segments on the same network, provided you have a switching hub
between them that allows them to communicate. Want to
know more about 10BaseT wiring configurations? Check out our wiring guide.
Thin Coax Cabling The geometric design that is formed when thin coax cabling is
used is called a linear or backbone configuration. The reason
for this is that thin coax is always arranged in a straight line of PCs,
hubs, or other devices. Thin coax networks always require termination,
which is the act of "plugging up" both ends of the network. Instead
of inserting an incoming thin coax cable directly into a PC, a T-connector is
inserted instead, splitting the network adapter's input port into two
separate ports. One port receives an incoming network cable; the other
receives an outgoing network cable. If the PC is at the end of the network
chain, a terminator plug is inserted into the empty hole of the T-connector. Thin coax is only used with 10Mbps Ethernet networks. Fast
Ethernet networks, which are 10 times faster than standard Ethernet, use
category 5 10BaseT cabling. The figure below shows three PCs connected together in a
backbone configuration. Note that Mixing 10BaseT & Coax Finally, thin coax backbones and 10BaseT cabling & hubs can
be connected together to allow for a wide variety of expansion options. In
the more complex example below, a thin coax backbone connects two
10BaseT hubs together, along with a computer in-between. Each hub, in turn,
branches off to still more computers with 10BaseT cabling. Note that the ends
of the thin coax backbone are properly terminated. How to Pick Cabling There are two things to consider when deciding on the type of
cable to use for your network. 1. How many PCs do you want to link together? The answers to these two questions will determine the cabling
that's best for you, and whether or not you'll need a hub. Use thin
coax cabling if you...
Common Problems & Solutions
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Avoid
Interference
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How to Wire a Network |
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How to Wire a Network Twisted Pair Cabling Twisted-pair (sometimes known
as 10BaseT) is ideal for small, medium, or large networks
that need flexibility and the capacity to expand as the number of network
users grows. We highly recommend using
10BaseT cabling for its amazing flexibility and reliability. In a twisted-pair network, computers
are arranged in a star pattern. Each PC has a twisted-pair cable
that runs to a centralized hub. Twisted-pair is generally more
reliable than thin coax networks because the hub is capable of correcting
data errors and improving the network's overall transmission speed and
reliability. Also known as uplinking, hubs
can be chained together for even greater expansion.
There are different grades,
or categories, of twisted-pair cabling. Category 5 is the most
reliable and widely compatible, and is highly recommended. It runs easily
with 10Mbps networks, and is required for Fast Ethernet. You can buy
Category 5 cabling that is pre-made, or you can cut & crimp your own. Category 5 cables can be
purchased or crimped as either straight-through or crossed. A Category
5 cable has 8 thin, color-coded wires inside that run from one end of the
cable to the other. Only wires 1, 2, 3, and 6 are used by Ethernet networks
for communication. Although only four wires are used, if the cable has 8
wires, all the wires have to be connected in both jacks. Straight-through cables are used for connecting
computers to a hub. Crossed cables are used for connecting a hub to
another hub (there is an exception: some hubs have a built-in uplink port
that is crossed internally, which allows you to uplink hubs together with a
straight cable instead). In a straight-through cable,
wires 1, 2, 3, and 6 at one end of the cable are also wires 1, 2, 3, and 6 at
the other end. In a crossed cable, the order of the wires change from
one end to the other: wire 1 becomes 3, and 2 becomes 6. To figure out which wire is
wire number 1, hold the cable so that the end of the plastic RJ-45 tip (the
part that goes into a wall jack first) is facing away from you. Flip the clip
so that the copper side faces up (the springy clip will now be parallel to
the floor). When looking down on the coppers, wire 1 will be on the far left.
Thin Coax Cabling Thin coax (also known as 10Base2)
is great for small home or office networks with two or three computers.
Similar to the cabling used to connect a VCR to a TV set, coax cabling is
inexpensive and easy to set up. In a thin coax network, which
is sometimes called a backbone, computers are arranged in a
"chain" with a beginning and an end. Each computer in a backbone
requires a network card, a T-connector, and at least one
incoming or outgoing coax cable. The computer at each end of the
network will also require a 50-ohm terminator plug.
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The Big Picture |
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The Big Picture Decide on a
peer-to-peer or client-server NOS. Choose one or the other
depending on the size & complexity of your network. Peer-to-peer allows
individual PCs to share each other's hard disks, printers, and other
resources. It's perfect for small networks with 16 or fewer users, or for
workgroups with one or more portable PCs. Popular packages include Windows 95
and Windows for Workgroups. Client-server NOSs, by
contrast, can handle heavier and more complex traffic loads than
peer-to-peer, and are designed for large networks or speed-critical
applications like video and multimedia. Popular packages include Windows NT
and Novell NetWare. Plan your cabling layout. Make a hardware &
software checklist. If you plan to install a
10BaseT hub, make sure that it's expandable, and that it has enough ports to
service all of your PCs. If you'll be using the hub in conjunction with a
thin coax backbone, make sure that it has both 10BaseT and thin coax ports
on-board. Get the correct hub for the type of Ethernet network that you're
installing--either standard 10Mbps Ethernet or Fast 100Mbps Ethernet. If
you'll be joining standard and Fast Ethernet segments together, you'll need a
switching hub in-between. After obtaining the network
software, adapters, cabling, and hub(s) (if any), install the network cabling
first, followed by the network adapters, and finally, the network software. Here's what you need:
If
you're using 10BaseT...
If
you're using thin coax...
Introducing the Instant Ethernet Series from Linksys.
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Price,
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