Specifications

Niagara Release 2.3
Revised: May 22, 2002 Niagara Networking & Connectivity Guide
Chapter 5 Connecting to an ISP
Niagara Considerations
5–2
System Architectures
Figure 5-1 provides examples of typical Niagara job configurations (system
architectures) for connecting JACE-4/5s to an ISP.
In the scenario presented in Figure 5-1, ABC Company has added two JACE-4/5s to
remote sites (for descriptions of the other sites shown in the figure, see the “System
Architectures” sections on page 3-1 and page 4-2).
In site 5, the JACE has been configured to dial an ISP. Upon connection, the JACE
receives a public, static IP address (and other settings for default gateway and DNS)
from the ISP. It can then send archives or alarms to the Web Supervisor (since the
Web Supervisor also has a public IP address). This setup also allows the Web
Supervisor (or the remote engineering station, if connected to the Internet or site 1)
to access the JACE using the public IP address of the JACE. The engineering stations
connect to acknowledge alarms, to maintain the devices using maintenance tools
such as Admin Tool, JDE, or web browser, or to pick up archives, if polled archiving
is set up. When the JACE loses its connection to the ISP, it immediately redials until
it is connected again. On the JACE-4/5, this configuration is known as captive ISP.
For more information, see the “About Captive ISP” section on page 5-8.
Site 6 also uses captive ISP, however, the JACE connects to a different ISP and this
ISP does not provide a static IP address. Rather, it gives out a different public IP
address each time the JACE connects to it. Therefore, the JACE at site 6 has been
configured to work with a company that provides DDNS services for
Internet-connected hosts (TZO.COM). Each time the JACE connects to the ISP and
receives a new IP address, it sends the new address to the DDNS company, which
maps the address to a fixed host name (JACE54.EasyIP.net). The JACE can still send
archives or alarms to the Web Supervisor (since the Web Supervisor also has a public
IP address). When the Web Supervisor (or the remote engineering station) wants to
contact the JACE, it uses the host name JACE54.EasyIP.net rather than the IP
address, since that may have changed since it last connected. For more information
on our implementation of DDNS on the JACE-4/5, see “Configuring DDNS on the
JACE-4/5,” page 5-22.