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Chapter 9 - Configuring Firewall/NAT Settings
ASUS SL1200
9.2.2 Dynamic NAT
Dynamic NAT maps an internal host dynamically to a globally valid Internet
address (m-to-n). The mapping usually contains a pool of internal IP
addresses (m) and a pool of globally valid Internet IP addresses (n) with m
usually greater than n. Each internal IP address is mapped to one external
IP address on a first come first serve basis. Figure 9.2 shows that PC B,
C and D are mapped to a globally valid IP address respectively, while PC
A does not map to any globally valid IP address. If PC A wants to go to
the Internet, PC A must wait until a global valid IP address is available.
For example, in Figure 9.3, PC B must disconnect from the Internet first to
allow PC A to access Internet.
Figure 9.2 Dynamic NAT – Four
Private IP addresses Mapped to
Three Valid IP Addresses
Figure 9.3 Dynamic NAT – PC-A can
get a NAT association after PC-B is
disconnected
