Avocent Cyclades-PR4000 installation manual NAT Network Address Translation, PR4000 With

Cyclades-PR4000

CHAPTER 13 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. These are used as local IP addresses. Figure 11.1 shows an example of the utility of NAT:

	Global Address Range	ftp	Networks
	- Network: 200.240.230.224	Server	192.168.0.0 &
	- Mask: 255.255.255.240	192.168.0.30	200.200.200.0
	Host
	Host
200.240.230.2		PC
PR4000 With	200.200.200.11		WWW
Expanded NAT	200.200.200.10		Server
			192.168.0.31
		192.168.0.5
	Router Ethernet Port
	Primary IP Address: 192.168.0.1
	Secondary IP Address: 200.200.200.1

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,

•Two servers that are accessed via the same global IP address, assigned statically.

Chapter 13 - NAT 117