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Ethernet & Mac Networks
Ethernet Networks
Most people think of Ethernet when they think of networks
because Ethernet was one of the first and most popular
network technologies. The components you need for an
Ethernet LAN are network interface cards (NICs) for your
computers, Ethernet cabling and a central hub.
There are several Ethernet standards or protocols which
support different speeds and use different types of cables.
One of the original standards 10Base2 uses thin coaxial or
"thin Ethernet" cable which looks like a smaller version of
your TV cable. In a thin coax network the computers (up to
30) are connected in series to a common central cable or
bus. This arrangement, referred to as bus topology, doesn't
require a hub. 10Base2 is an older, less flexible standard
and is falling out of use.
The most popular type of Ethernet networks use twisted pair
cable which is like the telephone wire inside the walls of
your home. The cable is thinner and more flexible than thin
coax but not as well shielded from electromagnetic
interference. Twisted pair cables come in five categories.
CAT3, 4 and 5 cables used for Ethernet networks have RJ-45
connectors that look like large telephone jacks.
CAT3 and CAT5 cable is the most common and transfer data at
a maximum of 16 Mbps and 100 Mbps respectively. Twisted pair
cable can be either unshielded (UTP) or shielded (STP). The
latter type of cable has a metal layer that cuts down on
electromagnetic interference in noisy environments. UTP is
used in most home LANs because it's inexpensive and
interference is uncommon.
In both the 10BaseT (10 Mbps) and 100BaseT (100 Mbps)
Ethernet standards, the "T" stands for twisted pair cable. A
10BaseT network can be wired with either CAT3 or 5 cables,
but a 100BaseT network requires CAT5. These two Ethernet
standards use a star topology where each computer is
connected to a central hub. Hubs are hardware devices with
multiple ports that act as central connection points in a
network. Typically, connecting more than two computers in an
Ethernet network requires a hub.
However you can connect two computers directly to each other
without a hub using a special UTP crossover cable. This is
less reliable but cheaper than a hub network. Gamers can use
this expedient method for head-to-head play with quick
response time. Crossover cables are also used to connect
hubs together. A crossover cable is $5-25 in price depending
on length.
Hubs
With more than two computers you'll need a hub; these
devices vary in size, speed and number of ports. The average
home network uses a 10BaseT system with a 10 Mbps hub. For
100BaseT (Fast Ethernet) networks, you'll need a 100 Mbps
hub. Dual speed 10/100 Mbps hubs with auto-sensing allow
users to use either speed.
Hubs have multiple ports from four to over 20 on a single
device. For each port, the hub has an indicator light so if
a segment of cable or NIC stops functioning you can figure
out which computer has the problem. A star topology network
with a hub will continue to function even when one of the
connections goes down.
For a home LAN, you'll probably use a stand-alone hub with 4
to 12 ports. Stand-alone hubs can be linked together to
expand your network. Larger networks use stackable or
modular hubs which can accommodate many more computers. Look
for a standard, inexpensive hub rather than a managed one
which comes with advanced features required by larger
networks.
A 10 Mbps hub with 4-5 ports can cost between $60-120. An
8-port model is roughly $130-160. A dual 10/100 Mbps hub
will be costlier than a 10 Mbps hub with the same number of
ports. Faster 100 Mbps hubs are the most expensive. You can
usually save some cash by getting a home networking kit
which typically includes a small 4-5 port hub plus NIC
cards.
Switches
Switches are devices that perform the same function as hubs
but operate more efficiently. When you send data through a
hub it's forwarded to the entire LAN then read by the
computer it's intended for. A switch sends data only to the
computer it's addressed to, reducing network traffic and
expanding capacity. Hubs can either send or receive data but
can't do both at the same time. With a switch, a computer
can simultaneously send and receive data, increasing the
speed of the network. Switches used to be more expensive
than hubs, but some kits now offer a switch at the same
price as a hub.
Network Interface Cards (NIC)
To link computers together in a network, each machine needs
a NIC. Network cards are usually designed for a specific
type of network protocol (Ethernet, Fast Ethernet) and media
(type of cable). Some cards can support multiple protocols
or multiple media. For example, you can get cards that have
both RJ-45 and BNC ports for either twisted pair or thin
coax cable.
Some PCs come with NICs built-in but most require the
addition of a card using either an ISA or PCI expansion
slot. What you choose will be dictated by the type of
expansion slots you have available. The PCI interface is
more efficient, but older computers may not have free PCI
slots. Laptops can use NICs that fit into the PC card slot.
Cards come in multiple speeds: 10 Mbps, 100 Mbps and 10/100
Mbps. Ordinarily, the speed of the NIC should match the LAN
speed, but it's possible to connect a computer with a 10
Mbps card to a 100 Mbps network. NICs also have different
bus widths which determine how much data can be transferred
to and from your computer at one time. The greater the bus
width the better. Cards range in price from $20-$300 with
faster 100 Mbps and 10/100 Mbps NICs being more expensive.
Another way of connecting to an Ethernet LAN is with a
USB-to-Ethernet adapter. These adapters let you add a
computer to an existing Ethernet network without adding a
NIC. The adapter attaches to a computer's USB port on one
end and an Ethernet cable on the other. However, the adapter
can only transfer data at 4 Mbps which doesn't take
advantage of the full networking speed of Ethernet.
Ethernet Kits
Manufacturers are making it easier to set up a home Ethernet
LAN by offering kits. These kits usually include a small 4-5
port hub, two NICs, cabling and software. Prices for a 10
Mbps kit start around $70 while 10/100 Mbps kits start
around $150. Of course, you can always buy the components
separately. Unlike wireless network products, Ethernet
products from different manufacturers are completely
compatible. A good kit should also include instructions for
installing hardware and configuring your operating system
for network access.
Mac Networks
Macs have had basic networking capabilities ever since they
had hard drives. All Macs come with a built-in networking
protocol called AppleTalk. Macs can use AppleTalk over an
Ethernet or Local Talk network. Local Talk connects older
Macs via their modem or printer serial ports. Newer Macs
usually have built-in Ethernet adapters.
Local Talk
Local Talk networks use either Mac printer cables or
ordinary phone cord. If you have several Macs or peripherals
to connect, you can daisy-chain the devices with phone cord
(RJ-11) and Phone Net adapters. These plug into a serial
port (usually the printer port) on one end and have two
phone jacks on the other. Local Talk only transfers data at
230 Kbps which is a far cry from Ethernet, but printer
cables, phone cord and Phone Net adapters (about $20) are
inexpensive. Macs with Ethernet but no printer ports can be
connected to a Local Talk network with an
ethernet-to-LocalTalk adapter.
Mac Ethernet
If you own an older Mac, it may not have an Ethernet card.
Check the model you have and see whether it has an open
expansion slot. Some Macs require Ethernet cards that are
specific to that model; others can use cards for the NuBus
or LC Communication slots. Older Power Macs and Quadras with
built-in Ethernet use a proprietary connector called an AAUI
port. An external adapter or transceiver is required to
connect a standard Ethernet cable (coax or twisted pair).
All newer Macs like the Power Mac G3, G4 and iMac ship with
built in Ethernet cards with standard RJ-45 connectors.
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