Configuring Nat Examples; Basic One-To-One Static Nat; Configuring Static Translation - Enterasys Security Router X-PeditionTM User Manual

Configuring NAT Examples

Configuring NAT Examples

Basic One-to-One Static NAT

The following example illustrates inside source address translation on the XSR, as shown in
Figure 5-11
10.1.1.1
reverse lookup
SA: 172.20.2.1
1. The user at 10.1.1.1 opens a connection to host 172.20.2.1.
2. The first packet the XSR receives from host 10.1.1.1 causes the router to check its NAT table.
–
–
3. The XSR replaces the inside local source address of 10.1.1.1 with the global IP address
200.20.2.1 and forwards the packet.
4. Host 172.20.2.1 receives the packet and responds to IP address 200.20.2.1.
5. The XSR receives the packet with the inside global destination IP address 200.20.2.1, it looks in
the table, and translates the destination address to the inside local destination address 10.1.1.1.
Then it forwards the packet to 10.1.1.1.

Configuring Static Translation

Only one command is required to configure NAT because static NAT is interface independent.
Optionally, you can configure multiple entries in the static translation table with the
source static
• XSR(config)#ip nat source static local-ip global-ip
+
5-38 Configuring IP
below.
Figure 5-11
Inside
Request
SA: 10.1.1.1
DA: 172.20.1
Inside
interface
Reply after
DA: 10.1.1.1
If a static entry was configured, the XSR proceeds to Step 3.
If no translation entry exists, the router decides that 10.1.1.1 must be translated
dynamically, selects a global address from the dynamic address pool, and creates a
translation entry.
command.
Sets the static translation
NAT Inside Source Translation
After Translation
SA: 200.2.2.1
DA: 172.20.2.1
External
interface
XSR
NAT Table
Private: 10.1.1.1
Global: 200.2.2.1
Outside
Internet
Reply
SA: 172.20.2.1
DA: 200.2.2.1
172.20.2.1
ip nat