Airlink EDGE/GPRS - Manual (Page 151)

PinPoint-E EDGE/GPRS - User Guide, version 2.32 145
Frequently Asked Questions and Technical Support
The PinPoint-E’s IP Addresses and Local Networking
On Your Wireless Service Provider’s network, for security reasons, some accounts set up to be
restricted to communication only from other devices on their network, called a Restricted IP or a
Private IP. If you had two modems on Your Wireless Service Provider’s network, they could com-
municate, but your computer, not using Your Wireless Service Provider as an ISP can’t. You could
normally still access the Internet using your PinPoint-E’s restricted or private IP because the
modem would use a proxy or gateway on Your Wireless Service Provider’s network.
Why Can’t I reach my PinPoint-E from the Internet? What is a Restricted or
Private IP?
However, if you need to be able to contact your PinPoint-E (or the devices behind it) directly,
instead of a Restricted IP (also called Private IP, Non-Routable IP, or Proxy APN), you will
need to contact Your Wireless Service Provider your cellular provider to get your account
changed to an Unrestricted IP (also called Public IP or Internet APN).
Note: Customized APNs are generally private and non-routable.
What is the difference between Private and Public mode?
When your PinPoint-E is powered on, ALEOS, acting as a PPP client, negotiates a PPP session
with Your Wireless Service Provider’s network at the conclusion of which it is assigned an IP
address by your cellular provider. How this address is further acted upon by the modem is deter-
mined by Private or Public Mode.
Public Mode (*HOSTPRIVMODE=0):
The IP address assigned by Your Wireless Service Provider is passed on to the devices connected
to the modem.
If there is a computer or device connected to the serial port of your modem, there are actually two
PPP sessions taking place. After your modem receives Your Wireless Service Provider assigned
IP address, a second PPP session is established between your computer or device and the modem
ultimately assigns that IP address to that computer or device connected to the serial port.
If there is a computer or device connected to the modem’s Ethernet port, the IP address assigned
by your cellular provider is passed on to the computer or device by the DHCP server in the
modem.
Private Mode (*HOSTPRIVMODE=1):
The IP address assigned by Your Wireless Service Provider is not the address that is assigned to
the computer or device connected to the PinPoint-E’s Ethernet port during the PPP negotiation or
DHCP IP assignment. Instead, the computer or device connected to the PinPoint-E on the Ether-
net port is assigned the IP address configured in *HOSTPRIVIP and uses the IP address config-
ured in *HOSTPEERIP to communicate to the modem.