Page 100 - M. Abrahim Thesis

Chapter (4) Network Design

If you are addressing a nonpublic intranet, a test lab, or a home network, these private
addresses can be used instead of globally unique addresses. Private IP addresses can be intermixed
with public IP addresses, as shown in Figure 4-22, to conserve the number of addresses used for
internal connections.
Connecting a network to the Internet using private addresses requires translating the private
addresses to public addresses. This translation process is called Network Address Translation (NAT).
A router usually is the device that performs NAT.

Figure 4-22 shown a Using Private IP Address Within the WAN

https://www.youtube.com/watch?v=5WfiTHiU4x8

https://www.youtube.com/watch?v=7_-qWlvQQtY

4.3 Introduction to Subnetting

Another way to conserve IP addresses, like CIDR, IPv6, and private addresses, is the use of
subnetting. This method of dividing full network address classes into smaller pieces has helped
prevent complete IP address exhaustion. Figure 4-23 shows a Class B network (131.108.0.0) divided
into three subnetworks. It is impossible to cover TCP/IP without mentioning subnetting. As a system
administrator, you must understand subnetting as a means of dividing and identifying separate
networks throughout the LAN.

It is not always necessary to subnet a small network, but for large or extremely large
networks, subnetting is required. Simply stated, subnetting a network means using the subnet mask
to divide the network and break a large network into smaller, more efficient, more manageable
segments, or subnets, as shown in Figure 4-24 and Figure 4-23.

This is like the American telephone system, which breaks the system into area codes, and
then exchange codes, and finally local numbers. These elements of the phone system are comparable
to network numbers, subnets, and individual host addresses, respectively, in an IP internetwork.

112