Nat Configuration; Nat Overview - Zte ZXR10 8900 Series User Manual

Address
Translation
Advantages
Address
Translation Rule
6
C h a p t e r

NAT Configuration

Table of Contents:

NAT Overview ...................................................................89

Configuring NAT ................................................................90
NAT Configuration Example .................................................96
NAT Overview
Rapid development of Internet speeds lack of IP addresses. To
alleviate this problem, RFC1631 and related RFC define Network
Address Translation (NAT), which is used widely. NAT is to map an
IP address from one address domain to another address domain.
One of this typical application is to map private IP address defined
in RFC1918 to available public IP address in Internet.
RFC 1918 gives the following definitions to private IP address:
Internet Assigned Numbers Authority (IANA) reserves three IP ad-
dresses for private network.
10.0.0.0 - 10.255.255.255 (Class A address segment)
172.16.0.0 - 172.31.255.255Class B address segment)
192.168.0.0 - 192.168.255.255 (Class C address segment)
When one user of private IP address needs to access public net-
work or one user in public network needs to access one server
with private IP address, administrator needs to set corresponding
address translation rule.
With network address translation, enterprises can use quite a few
Internet public IP addresses to access Internet, which relieves lack
of IPv4 addresses and meanwhile provides certain security. NAT
has the following advantages:
� Guarantee that intra-users of enterprises using private IP ad-
dresses can access Internet normally;
� Protect intranet, hide intranet topology and actual IP, and re-
duce direct attacks.
� Protect internal server that provides service externally and pro-
vide the function of load balancing.
FW card can configure NAT rules flexibly according to user net-
work planning and function demands. When user defines address
translation rules on FW card, firstly he needs to define source and
destination of this rule, that is source address range and destina-
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