ZyXEL Communications LTE2566-M634 - Two Points to Remember about Trigger Ports

Chapter 10 NAT
LTE2566-M634 User’s Guide
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Figure 59 Trigger Port Forwarding Process: Example
1 Jane requests a file from the Real Audio server (port 7070).
2 Port 7070 is a “trigger” port and causes the LTE2566-M634 to record Jane’s computer IP address. The
LTE2566-M634 associates Jane's computer IP address with the "incoming" port range of 6970-7170.
3 The Real Audio server responds using a port number ranging between 6970-7170.
4 The LTE2566-M634 forwards the traffic to Jane’s computer IP address.
5 Only Jane can connect to the Real Audio server until the connection is closed or times out. The LTE2566-
M634 times out in three minutes with UDP (User Datagram Protocol), or two hours with TCP/IP (Transfer
Control Protocol/Internet Protocol).
10.5.5 Two Points To Remember About Trigger Ports
1 Trigger events only happen on data that is coming from inside the LTE2566-M634 and going to the
outside.
2 If an application needs a continuous data stream, that port (range) will be tied up so that another
computer on the LAN cannot trigger it.