The easiest way to set-up your network is to click this
let us do it for you - BUT if you would like to try and
do it yourself, then you may find the notes below helpful.
WHAT IS A LOCAL AREA NETWORK?
A local area network connects all your computers, printers etc. together.
WOULD I WANT TO DO THAT?
Connecting your computers and printers together allows you to
share your resources. For example; one printer can service many
users – they don’t
all need printers connected to their PC’s. Only one set of templates
is required. Rather than every user having a number of templates on their
PC, one central set of templates is shared between all users. Ensuring that
everyone is using the same template guarantees a uniform look to your company’s
documents. Sharing a single file is especially important with
dynamic data such as in a database.
Imagine that you have a simple
database to store data about all your customers and orders.
If two or more users need access to the database then they
both need a copy of it on their PC’s. If one user changes
something then the two copies will be different,
until the files are merged and copied back to both users.
disappears with a LAN, since both users
can share the same files, also that data
only be accessed from those two
particular PC’s which may be inconvenient. If
you have more than a handful of people using PC’s
in your company then installing a LAN can
make user management and security easier
to manage because you only need to set
up user accounts for each user once on
a central computer designated as a domain
rather than having to set
up access for each user on each PC, something
which is usually overlooked;
PC’s are left open without
any sort of access control making sensitive
available to everyone in the company, not
desirable in the light
a recent Computer Security Institute study
which states that 70% of organisations
polled had experienced
incidents and that 60% of those were committed
DOES IT COST?
Local area networks are now so common that
the cost is minimal. Somewhere in the order
of £20 - £25 per PC, depending
on the number of PC’s
that you want to connect and how far apart they are.
WHAT DO I NEED?
Each device (PC, Printer etc.) requires a Network Interface
Card (NIC). These are available at almost every computer store.
one of the PC’s
internal slots and are usually plug & play. You will need
a switch or hub* into which they all plug and some patch cables
(or a structured
infrastructure in a large multi office environment).
SWITCHES Vs HUBS:-
These are two devices for connecting computers together. A
hub is rather like a main road with a number (usually 4, 8
it. There is no traffic control, therefore data joining the
main highway from a side road often collides with data already
the highway. This
data is damaged and lost. The device that sent the data will
realise that this
has happened because it won’t get a reply and will send
the data again – maybe
this time it will collide, maybe not. Following each collision
the sending device waits longer before re-sending the data.
As you can
see this slows
down the network, degrading performance significantly on a
busy network. Switches are similar but have traffic control
should not occur. Additionally, hubs send all data to every
device on the network. This means that each device is continually
for someone else. The devices have to inspect the IP headers
and look at the destination address. If it is not for them
quick process, but it still has to be done and takes a finite
time. Switches only send data to the device it is destined
for, thus reliving
of unnecessary processing of network data. In summary switches
make for a much more efficient network, and on busy networks
They are, as you would expect more expensive than hubs.
HOW EASY IS IT?
Generally speaking, setting up a small network is reasonably
easy. Getting it all to work usually involves fighting with
generally with the drivers for the NIC’s, but if you
are used to installing devices in your home PC then you won’t
have too much trouble. You should spend some time deciding
who needs to access what,
take the trouble
up security on the shares. Not difficult, but you will be surprised
at how long you spend getting this bit right.
HOW TO DO IT
As stated above you need to install a NIC into each device
to be connected. The devices are then all plugged into a switch
and the PC’s
configured to use a common protocol, nowadays universally TCP/IP.
Finally files and directories (Network Resources or resources
for short) are
shared by setting up sharing in windows explorer. Lets take
a closer look at how
to do this:
- Install the NIC cards as per the manufacturers instructions
- Open the network control applet in the control panel and
- In the resulting dialogue
box, tick “File & Print
- In the TCP/IP section select
the manual IP address option and enter a valid address
and mask – you do not
need to enter a gateway or DNS server setting.
NB Valid IP addresses refer to technically and legally valid.
To ensure compatibility with Internet connections (Internet
communication uses IP addresses) there are three ranges of
private addresses. These are: -
- 10.0.0.0 – 10.255.255.255
- 172.16.0.0 – 172.31.255.255
- 192.168.0.0 – 192.168.255.255
The subnet mask defines which
part of the address is network and which is host, or computer.
The subject of IP addresses
and subnet masks gets rather technical, but I suggest that
you use 255.255.255.0 as the mask on ALL your PC’s,
and IP addresses of, say 10.0.0.1 – 10.0.0.2 etc. Each
device MUST have a different address with the SAME mask and
the first three octets (10.0.0) MUST be the same on each
IP addresses are numbers between 0 and 255. Using
a mask of 255.255.255.0 means that you can’t use 0
or 255 in the last octet, any number in between is fine though.
In Windows explorer, right click the folder or file that
you want to share and click on the ‘Sharing’ option.
Enter a name for the share and that’s it!
NB: Windows NT, Windows 2000
and Windows XP all use a disk format called NTFS. This provides
which you can set so that only certain users can access the
shared data. If you right click the newly shared folder and
select properties and there is a security tab at the top
then the PC uses NTFS and you can use this facility.
the share from another PC on the network open the ‘Network Neighbourhood’ icon
on the desktop and you should see the computer names of the
on the network. Double clicking on these will show the resources
shared by these devices. Double clicking the folders will
open them and likewise the files within.
This is a brief
overview of how to set up a basic network, sometimes it takes
a bit of fiddling to get it all working
and there is a lot of fine tuning that can be done in terms
of security and functionality, see one of the many windows
books for further details, and good luck.
WHAT ARE THE RISKS?
Generally there are few risks when setting up a small network.
The obvious thing is that there are cables between every device
that need to be well
routed so as not to cause a trip hazard. Security of data is another concern,
you may not want the new office assistant to be able to access confidential
accounts data or buy prices etc. I strongly recommend that you use PC’s
running one of the operating systems, which use NTFS so that you can control
WHO has access to WHAT.
CONSIDERATIONS FOR LARGER NETWORKS:-
The network model described above is fine for a limited
number of devices, say up to 50 or so PC’s. For
larger networks it becomes necessary to use what is
called a routed network. As mentioned earlier IP addresses
a network part and a host (device) part defined by the subnet mask.
This is rather like a postal address where there is
a house number (device part)
and a street, town, county part (network part). Devices with the
same network portion of an IP address are like houses
in the same street.
When you connect
to a device by name your PC needs to resolve that name to an IP address,
further the IP address then needs
to be resolved to a MAC address.
MAC addresses are the real
addresses that devices use to communicate. They consist of six 2
byte hexadecimal numbers;
something like “00-00-35-F4-C3-59”. Since
it is impossible to ever remember these numbers for
we use logical addresses and names which we mere
humans can handle more easily.
The way in which devices resolve these
addresses is by sending a query to EVERY device on
the network (network here refers
to the number of hosts with the same network portion
of the IP address). These queries are called broadcasts.
a lot of these broadcasts going on in even a small
network. If you were to set up a network with hundreds
there would be so many broadcasts traversing the network
that there would be little time left for actual data!
networks are networks where the IP addresses of devices
span a number of different network portions. This means
each network portion has it’s own broadcasts,
but these are not forwarded to devices on a different
subnet. A subnet
refers to a network which shares the same network
portion of IP address. Also each subnet is said to
be a separate
broadcast domain, since broadcasts are contained
within a subnet.
Using routed networks controls the broadcast problems
and makes it easier to administer since they use
layered addressing – like
the house number and the street name idea mentioned earlier.
It is easier to remember that all your account department
PC’s are in a road with one name and your sales PC’s
are in a different road. Immediately you can tell
which function a device has just by the street name.
Compare this to a flat
addressing approach, like National Insurance numbers.
Trying to remember 500 of those is much harder!
Routed networks use
devices called routers to connect the various subnets.
These devices look at the data and decide
where to send it next so that it eventually arrives
at the correct address. The ‘Default Gateway’ referred
to in the PC’s IP set-up dialogue box is the IP address
of that subnet’s router. Broadcast traffic will not
traverse routers, this eliminates the problems of high broadcast
traffic on a large network, but it means that the PC’s
on different subnets cannot ‘see’ each other
since they use broadcasts to resolve names! This problem
is overcome by the use of either ‘Windows Internet
Naming Service’ or WINS for short on Microsoft systems,
or ‘Domain Name System’ or DNS for short
on all other systems.
From the above it is clear that if your network
grows to an extent where it becomes necessary to segment
routers, you need to install a WINS or DNS server as
there is some particular reason not to use WINS or
DNS on your network – and I can’t think of one! -
there is a file on every PC called ‘Hosts’. If
all the IP addresses and device names of all the devices
on the network are entered in this file then the PC will
resolve names by looking them up in this file. Clearly each
device on the network requires identical copies of this file
for everything to work correctly, and if a change is made
ALL the PC’s will need their files updated,
quite a task!
It is usual practice to use a centralised configuration
for all the PC’s on the network. Manually administering
the settings of 50 or more PC’s can be quite a time
consuming and ongoing process! There is a protocol called ‘Dynamic
Host Configuration Protocol’ DHCP for short, which
is used for this purpose. This basically dishes out IP address,
Default Gateway, DNS server addresses and other configuration
data to a PC each time the PC boots up. This is the process
used when the ‘Obtain IP address and DNS server settings
automatically’ option is ticked in the IP properties
dialogue box of a PC’s network configuration.
Use switches in preference
to hubs – they
considerably increase performance in a busy network.
If the network contains more than 40 –50 devices
it is usual to use a routed network.
All but the smallest networks should have a Domain Controller server to centrally
manage users and security.
Routed networks usually have a Name resolution server – WINS or
It is desirable to have a DHCP server in a network of this size or bigger.