User's Manual

Configuring Network Address Translation
308625-14.00 Rev 00
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Configuring Network Address Port (N-to-1) Translation
Using network address port (N-to-1) translation, you can map many local
addresses to one global address.
When NAT receives a packet on the local interface, the following events occur:
1. NAT determines that the local source address falls within the range configured
for N-to-1 translation.
2. NAT assigns the packet a global source address and a unique port number.
3. NAT transmits the packet on the global interface.
In Figure 2-6
, for example, the network administrator has set up a local address
range of 55.0.0.0 through 55.255.255.255 and associated this range of local
addresses with global IP address 192.1.1.1.
Figure 2-6. N-to-1 Translation (Local to Global)
Note:
N-to-1 translation is valid only for TCP/UDP packets. All non-TCP/
UDP packets with addresses that fall within the configured local address range
are dropped.
IP0075A
NAT
N-to-1 translator
NAT
N-to-1 translator
Global interface
Local interface
Global source address: 192.1.1.1
Port: 12000
Local source address: 55.0.0.1
Port: 2001
Global source address: 192.1.1.1
Port: 54000
Local source address: 55.0.0.2
Port: 2222
Host A Host B
Host A Host B