ZyXEL Communications P-2812HNU-51c manual 188

Chapter 8 Network Address Translation (NAT)

port), the P-2812HNU-51c forwards the traffic to the LAN IP address of the computer that sent the request. After that computer’s connection for that service closes, another computer on the LAN can use the service in the same manner. This way you do not need to configure a new IP address each time you want a different LAN computer to use the application.

For example:

Figure 83 Trigger Port Forwarding Process: Example

Jane’s

Computer

Real Audio Server

1Jane requests a file from the Real Audio server (port 7070).

2Port 7070 is a “trigger” port and causes the P-2812HNU-51c to record Jane’s computer IP address. The P-2812HNU-51c associates Jane's computer IP address with the "open" port range of 6970-7170.

3The Real Audio server responds using a port number ranging between 6970-7170.

4The P-2812HNU-51c forwards the traffic to Jane’s computer IP address.

5Only Jane can connect to the Real Audio server until the connection is closed or times out. The P-2812HNU-51c times out in three minutes with UDP (User Datagram Protocol) or two hours with TCP/IP (Transfer Control Protocol/Internet Protocol).

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	P-2812HNU-51c User’s Guide