ZyXEL Communications VMG8825-B Series User Manual page 173

For example:
Figure 88 Trigger Port Forwarding Process: Example
Jane requests a file from the Real Audio server (port 7070).
1
Port 7070 is a "trigger" port and causes the VMG to record Jane's computer IP address. The VMG
2
associates Jane's computer IP address with the "open" port range of 6970-7170.
The Real Audio server responds using a port number ranging between 6970-7170.
3
The VMG forwards the traffic to Jane's computer IP address.
4
Only Jane can connect to the Real Audio server until the connection is closed or times out. The VMG
5
times out in three minutes with UDP (User Datagram Protocol) or two hours with TCP/IP (Transfer Control
Protocol/Internet Protocol).
Click Network Setting > NAT > Port Triggering to open the following screen. Use this screen to view your
VMG's trigger port settings.
Figure 89 Network Setting > NAT > Port Triggering
Chapter 11 Network Address Translation (NAT)
DSL
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