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N300 WiFi Router (N300R) User Manual
5-10 Fine-Tuning Your Network
v1.0, May 2012
Configuring Port Triggering
Port triggering is a dynamic extension of port forwarding that is useful in these cases:
• More than one local computer needs port forwarding for the same application (but not
simultaneously).
• An application needs to open incoming ports that are different from the outgoing port.
When port triggering is enabled, the router monitors outbound traffic looking for a specified
outbound “trigger” port. When the router detects outbound traffic on that port, it remembers the IP
address of the local computer that sent the data. The router then temporarily opens the specified
incoming port or ports, and forwards incoming traffic on the triggered ports to the triggering
computer.
While port forwarding creates a static mapping of a port number or range to a single local
computer, port triggering can dynamically open ports to any computer that needs them and can
close the ports when they are no longer needed.
To configure port triggering, you need to know which inbound ports the application needs. Also,
you need to know the number of the outbound port that will trigger the opening of the inbound
ports. You can usually determine this information by contacting the publisher of the application or
user groups or newsgroups.
To set up port triggering:
1. Select Port Forwarding/Port Triggering under Advanced in the main menu. The
Forwarding/Port Triggering screen displays (see Figure 5-1 on page 5-7 ).
Note: If you use applications such as multiplayer gaming, peer-to-peer connections, real-
time communications such as instant messaging, or remote assistance (a feature in
Windows XP), you should also enable Universal Plug and Play (UPnP) according
to the instructions in
“Using Universal Plug and Play” on page 5-14 .