How port forwarding differs from port triggering – NETGEAR wndr3700 User Manual

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RangeMax™ Dual Band Wireless-N Gigabit Router WNDR3700 User Manual

Customizing Your Network Settings


v1.3, October 2009

The destination address is the IP address of, which is the address of
your router.

The destination port number is 80, the standard port number for a Web server process.

The remote computer then sends this request message through the Internet to your router.

2. Your router receives the request message and looks in its rules table for any rules covering the

disposition of incoming port 80 traffic. Your port forwarding rule specifies that incoming port
80 traffic should be forwarded to local IP address Therefore, your router
modifies the destination information in the request message:

The destination address is replaced with

Your router then sends this request message to your local network.

3. Your Web server at receives the request and composes a return message with

the requested Web page data. Your Web server then sends this reply message to your router.

4. Your router performs Network Address Translation (NAT) on the source IP address, and sends

this request message through the Internet to the remote computer, which displays the Web
page from

To configure port forwarding, you need to know which inbound ports the application needs. You
usually can determine this information by contacting the publisher of the application or user
groups or newsgroups.

How Port Forwarding Differs from Port Triggering

The following points summarize the differences between port forwarding and port triggering:

Port triggering can be used by any computer on your network, although only one computer can
use it at a time.

Port forwarding is configured for a single computer on your network.

Port triggering does not need to know the computer’s IP address in advance. The IP address is
captured automatically.

Port forwarding requires that you specify the computer’s IP address during configuration, and
the IP address must never change.

Port triggering requires specific outbound traffic to open the inbound ports, and the triggered
ports are closed after a period of no activity.

Port forwarding is always active and does not need to be triggered.

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