Cyclades-PR1000 Access Router Installation Manual

Cyclades-PR1000

Chapter 11 - NAT

CHAPTER 11 NAT (NETWORK ADDRESS TRANSLATION)

NAT exists to convert local IP addresses into Internet “global” IP addresses. Internet IP addresses are assigned

by Internet providers. Due to the explosion of the internet, these numbers are scarce. Certain ranges of IP

addresses are reserved for internal use only — they may not have a direct connection to the Internet (for reference,

they are 10.0.0.0 - 10.255.255.255, 172.16.0.0 - 172.16.255.255, and 192.168.0.0 - 192.168.255.255). These

are used as local IP addresses. Figure 11.1 shows an example of the utility of NAT:

WWW

Server

Host

Global Address Range

- Network: 200.240.230.224

- Mask: 255.255.255.240

PR1000 With

Expanded NAT

200.240.230.2

Router Ethernet Port

Primary IP Address: 192.168.0.1

Secondary IP Address: 200.200.200.1

200.200.200.10

200.200.200.11

192.168.0.5

Networks

192.168.0.0 &

200.200.200.0

Host

ftp

Server

192.168.0.31

192.168.0.30

FIGURE 11.1 NAT EXAMPLE

In this example, the company has:

• 14 global IP addresses available for NAT, 200.240.230.225 to 200.240.230.238,

• Two networks connected to the router via the Ethernet Interface, one of which will be translated,