User`s guide

4000/5000 Modems’ User Guide

Chapter 6: IP Networking Features

As briefly mentioned in Chapter 1, the modem acquires an IP address from the

wireless network upon establishing a connection. The modem runs its own IP stack,

thus allowing a remote user to communicate with the modem or an attached terminal

behind the modem accordingly. This could be done via any terminal session, BVDM, or

any software application that is using the WAN IP address of the modem and the

appropriate port number as destination parameters.

It is important to note that some carriers limit this feature and a user has to

particularly ask the carrier for allowing incoming IP data traffic. Also, if the intended

party to be reached is a terminal behind the modem, the appropriate port forwarding

and LAN IP configuration settings have to be set.

Remote connectivity feature also is vital for remote modem diagnostics or AT

command interface.

Port Forwarding

Port forwarding (also referred to as tunneling) is the act of forwarding a network port

from one machine to another. One use of this technique can allow an external user to

reach a port on a private IP address from the outside via a NAT (network address

translation) -enabled router. This allows remote computers to connect to a specific

computer within a private LAN, depending on the port used to connect.

Since the 4000/5000 series modem is a NAT enabled router. The WAN device

connecting to the modems wireless WAN IP can not access devices/servers on the LAN

without specifically configuring the modem to forward the port(s) to the LAN

devices/servers. Applications running on remote hosts or servers connect to the

modem via the internet and the 1xRTT network.

Below is an exemplar sketch of how different applications running on various servers

are able to reach their intended destinations (PCs in this particular case). The PCs are

connected to the BlueTree modem – via Ethernet crossover cable, hubs and patch

cables, wireless router or a wireless access point. In the case below a wireless access

point is used and is connected via an Ethernet cable to the BlueTree modem. The

remote applications use the wireless IP address of the modem (the WAN IP assigned

by the wireless network carrier) as the destination IP address. The traffic received by

the modem on various ports are forwarded according to their ports and their

corresponding port forwarding rules to a LAN IP address.

To set Port Forwarding, click on the Port Forwarding tab. The WAN Port is the

destination port number used by the remote application. The LAN Port is where the

data is forwarded to; typically the WAN port and LAN port are the same. Select the

appropriate protocol (TCP or UDP). Submit the new settings after editing this page.