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EXTERNAL NAT PORT
INTERNAL NAT PORT
[ IP < Secton ID > ] configure commands and example keywords for Example Three
EXTER NAL NAT PORT
INTERNAL NAT PORT
NAT PASSTHRU RANGE
FINAL NOTES
IMPORTANT DISCLAIMERS
Not all Compatible Systems devices have Network Address Translation ability. Due to memory
limitations and software code size, the following routers do not have NAT software:
MicroRouter 900i♦
MicroRouter 1000R♦
RISC Router 3000E♦
RISC Router 3400R♦
RISC Router 3800R♦
1.
NAT functionality is available on Compatible Systems device IP interfaces with one important
exception. A WAN interface can be used as the NAT external port only if its IP address is assigned in
the device's configuration. NAT cannot function on a WAN interface which has its IP address
assigned by a dial−up, PPP negotiation.
2.
Compatible Systems NAT implementation supports Real Audio and CUSeeMe.3.
The NAT software in Compatible Systems devices does not yet support several IP Applications.
Some of the more popular IP applications not yet supported are:
IRC (Internet Relay Chat)♦
X Windows♦
IPSec♦
4.
EXPLANATION OF NAT FUNCTIONALITY
Reasons for Network Address Translation
IP Address Availability
The Internet is still growing at an almost exponential rate, with a finite number of Internet
Protocol (IP) addresses available. Several solutions to this future shortage of IP addresses
have been proposed and are currently being developed. One of the solutions currently being
used is Network Address Translation (NAT).
NAT can ease the IP address shortage by creating "local" or "private" networks (also referred
to as NAT Networks in this document) which are connected to the "official" Internet/External
Network using only a single "global" IP address. This "global" IP address would have
originally been assigned by the Internet Network Information Center (InterNIC), probably
through an Internet Service Provider (ISP) or System Administrator.
For example, a private group can create a local network of ten workstations with an IP
addressing system which is totally independent of the Internet, and connect their network to
the Internet with one "global" Internet IP address. In this case, the group would only need a