How to Set up a Private Network
A private network is one which either does not connect to the internet, or is
connected indirectly using NAT (Network Address Translation) so its addresses
do not appear on the public network. However, a private network allows you to
connect to other computers that are on the same physical network. This is
desirable when you wish to communicate with a group of other computers or share
data and internet connectivity is not necessary.
1. Plan your network. This is probably the hardest part of setting up a network.
Draw any routers you may be using to separate major portions of your network first.
Smaller private networks do not require routers, but may still use them for
administrative reasons. Routers are only required if:
a. Dividing your network into multiple smaller networks,
b. Allowing indirect internet access using NAT.
Next, add any switches and hubs. For small networks, only one switch or hub may be necessary.
Draw boxes to represent the computers and lines connecting the devices together.
This drawing will serve as your network diagram.
Although diagrams intended only for your own use may use any symbols you desire,
use of industry standard symbols make this task simpler and eliminates confusion
for others. Typical industry standard symbols are:
• Routers: Circle with four arrows arranged in a cross. Or just
a cross if drawing a quick draft.
• Switches: Square or rectangle, with four staggered arrows, two
in each direction. Represents the concept of signals being "switched" - relayed only
out the port which leads to the intended user based on address.
• Hubs: Same as switch, with a single double-headed arrow. Represents
the concept of all signals being blindly repeated out all ports without concern for
which port leads to the intended recipient.
Lines and squares can be used to represent connections leading to computers.
2. Create an address plan
• IPv4 (IP ver. 4) addresses are written like this: xxx.xxx.xxx.xxx
(four numbers separated by three dots), in all RFC-1166 compliant countries. Each number
ranges from 0 to 255. This is known as "Dotted Decimal Notation" or "Dot Notation" for
short. The address is divided into two portions: the network portion and the host portion.
For "Classful" networks, the network and host portions are as follows:
("n" represents the network portion, "x" represents the host portion)
When the first number is 0 to 127 - nnn.xxx.xxx.xxx (ex. 10.xxx.xxx.xxx)
These are known as "Class A" networks.
When the first number is 128 to 191 - nnn.nnn.xxx.xxx (ex. 172.16.xxx.xxx)
These are known as "Class B" networks.
When the first number is 192 to 223 - nnn.nnn.nnn.xxx (ex. 192.168.1.xxx)
These are known as "Class C" networks.
When the first number is 224 to 239 - The address is used for multi-casting.
When the first number is 240 to 255 - The address is "experimental".
Multicast & Experimental addresses are beyond the scope of this article. However,
do note that because IPv4 does not treat them the same way as other addresses they
should not be used. For simplicity "non-classful networks", sub-netting, and CIDR will
not be discussed in this article.
The network portion specifies a network; the host portion specifies an
individual device on a network.