Using the previous configuration, the figure illustrates the static NAT translation process between the client and the web server. Usually static translations are used when clients on the outside network (Internet) need to reach servers on the inside (internal) network.
1. The client wants to open a connection to the web server. The client sends a packet to the web server using the public IPv4 destination address of 209.165.201.5. This is the inside global address of the web server.
2. The first packet that R2 receives from the client on its NAT outside interface causes R2 to check its NAT table. The destination IPv4 address is located in the NAT table and is translated.
3. R2 replaces the inside global address of 209.165.201.5 with the inside local address of 192.168.10.254. R2 then forwards the packet towards the web server.
4. The web server receives the packet and responds to the client using the inside local address, 192.168.10.254.
5a. R2 receives the packet from the web server on its NAT inside interface with source address of the inside local address of the web server, 192.168.10.254.
5b. R2 checks the NAT table for a translation for the inside local address. The address is found in the NAT table. R2 translates the source address to the inside global address of 209.165.201.5 and forwards the packet out of its serial 0/1/0 interface toward the client.
6. The client receives the packet and continues the conversation. The NAT router performs Steps 2 to 5b for each packet. Step 6 is not shown in the figure.