Dialup DDNS scenario

In this scenario (Figure 2), a JACE uses an onboard dialup modem for typical access (its Ethernet port is used only during on-site maintenance by the installing SI, when connected to the SI’s laptop PC). The slow response of a dialup connection is tolerated for some reason(s), such as unavailability of cable or DSL service at this location, or perhaps cost savings.

Starting in AX-3.7, dialup support was dropped in NiagaraAX, so this particular configuration is not supported in AX-3.7 or later.

Figure 2. Dialup DDNS scenario

Almost always in this scenario, the JACE has dialup operation set up for “Captive Network,” as configured in that section of its platform’s Dialup Configuration view. This forces the JACE to attempt to stay “dialup connected” to its ISP as much as possible. Dial out to the ISP occurs, for example, immediately after a reboot, or upon a loss of the dialup connection. Note that some ISPs limit the amount of “continuous time” for any dialup session—and so this is configurable in a “Max Connect Time” property, within the JACE’s captive network setup. See the Dialup section of the DDNS Configuration guidelines for an example setup.

Upon making a dialup connection, the JACE receives a dynamically allocated IP address from the ISP, which usually varies for each dialup session. In turn, through its DDNS configuration, the JACE sends its IP address to the DDNS provider (TZO), where it is registered for dynamic DNS. At this point the JACE is now reachable at its DDNS “domain name” through any Internet connection, for example, “myjace.tzo.com”.

This is quite different from a “normal” dialup connection, in the following ways:

Any Internet-connected browser or Workbench user can reach it, not just one dialing directly to the JACE modem (via another modem connection). However, note that connection response is still slow, because of the narrow bandwidth of the JACE dialup connection.
Multiple connections can occur simultaneously through this IP connection (resolved by DDNS). For example, the JACE can be archiving history data to a remote Supervisor station and/or routing alarms to that station, at the same time being accessed by one or more browser users, or even hosting a platform connection in Workbench. However, again note that response is often quite slow, and even more so during multiple connections.