Trigger Port Forwarding; Trigger Port Forwarding Example - Nortel BSR252 Configuration - Basics

Table 28 Address Mapping edit
Label
Global End IP
Apply
Reset

Trigger Port Forwarding

Some services use a dedicated range of ports on the client side and a dedicated
range of ports on the server side. With regular port forwarding you set a
forwarding port in NAT to forward a service (coming in from the server on the
WAN) to the IP address of a computer on the client side (LAN). The problem is
that port forwarding only forwards a service to a single LAN IP address. In order
to use the same service on a different LAN computer, you have to manually
replace the LAN computer's IP address in the forwarding port with another LAN
computer's IP address,
Trigger port forwarding solves this problem by allowing computers on the LAN to
dynamically take turns using the service. The Business Secure Router records the
IP address of a LAN computer that sends traffic to the WAN to request a service
with a specific port number and protocol (a trigger port). When the WAN port on
the Business Secure Router receives a response with a specific port number and
protocol (incoming port), the Business Secure Router forwards the traffic to the
LAN IP address of the computer that sent the request. After that connection
closes, another computer on the LAN can use the service in the same manner. This
way, you do not need to configure a new IP address each time you want a different
LAN computer to use the application.

Trigger Port Forwarding example

Figure 40
Chapter 8 Network Address Translation (NAT) Screens 143
Description
This is the ending Inside Global IP Address (IGA). This field is N/A
for One-to-One, Many-to-One and Server mapping types.
Click Apply to save your changes to the Business Secure Router.
Click Reset to begin configuring this screen afresh.
illustrates an example of trigger port forwarding.
Nortel Business Secure Router 252 Configuration — Basics