Specifications

Niagara Release 2.3
Revised: May 22, 2002 Niagara Networking & Connectivity Guide
Chapter 5 Connecting to an ISP
Niagara Considerations
5–4
Connecting Hosts via Cable or DSL
Options 3 and 4 show connectivity to the Internet from any Niagara host via a cable
or DSL modem. Note that with DSL or cable, the connection to the Niagara host is
via the Ethernet connection, rather than the dial-up connection (as it is with a
traditional modem). The cable or DSL provider issues a public, static IP address (and
other settings) to the Niagara host.
Most cable and DSL connections are “always on”, so there may be no need to
implement software that initiates connection on disconnect. If necessary (when a
dynamic IP address is assigned), DDNS can be implemented on JACE-NPs or Web
Supervisor, but not on a JACE-4/5, as its DDNS implementation works on the dial-up
interface only.
Connections with NAT
Option 5 shows the implementation of a NAT device in a DSL/cable scenario. The
provider issues a public, static IP address (and other settings) to the account holder.
That public address and other settings are used on the Ethernet port of the router
connected to the DSL or cable modem. The router is configured with a private IP
address on the Ethernet connection to the Niagara host, and it assigns another private
IP address (and other settings) to the Niagara host. Note that the NAT function could
also occur at the ISP rather than in a router located at the customer site.
This NAT scenario may not work with DDNS. In the example the Niagara host is
assigned a private IP address. This is typically the address that the host reports to the
DDNS provider. The host is not reachable at that private address. You would need to
find some kind of software that updates the DDNS provider each time the router’s
external IP address changes. That could be either:
• Client software from the DDNS provider. Note that the JACE-4/5 does not
support the use of this client software in its DDNS configuration.
• Software to run on a specific model of router to handle the updating when the
IP address changes on the router. These are commonly available on the Internet
on sites which discuss home networking.