ZyXEL Communications LTE3311 series - Two Points to Remember about Trigger Ports

Chapter 10 NAT
LTE3311 Series User’s Guide
99
Figure 62 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 LTE3311 to record Jane’s computer IP address. The
LTE3311 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 LTE3311 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
LTE3311 times out in three minutes with UDP (User Datagram Protocol), or two hours with TCP/IP
(Transfer Control Protocol/Internet Protocol).
10.6.5 Two Points To Remember About Trigger Ports
1 Trigger events only happen on data that is coming from inside the LTE3311 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 can’t trigger it.
Jane’s computer
Real Audio Server
Port 7070