Digi Connect® Application Guide Cellular IP Connections (Uncovered)
Introduction
When connecting remote devices to a cellular network, users must take into account the requirements of the application and the available IP addressing schemes available by the wireless telco. Specifically, consideration must be given in wireless solutions regarding which side of the connection initiates communication. Each wireless carrier handles usage and management of IP addresses differently; therefore customers must be prepared to carefully examine the type of IP connectivity options available and make sure that they work with the targeted application. The purpose of this paper is to help users understand the IP connectivity options available and steer them towards the best solution based on: • • • • Type of Cellular Application o Mobile Originated vs. Mobile Terminated IP Addressing Schemes o Static vs. Dynamic o Private vs. Public IP Addressing on GSM Networks IP Addressing on CDMA Networks

Mobile Applications
In order to establish what type of application your scenario falls into, you must first ask yourself: “Where is the traffic originating from?” or said differently, “Which end is the first to initiate the connection?” Consider this simple diagram:
Remote Site Remote LAN / Devices Host Site (HQ)

Cellular IP Network

Customer WAN or Internet

Digi Connect WAN/ RG

Mobile Interface gets IP address from Cellular Provider

The answer would fall among these three possible applications:

7/18/2005

Digi International

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Cellular IP Connections (Uncovered) • Mobile Originated – Remote device makes first communication. A remote device or workstation initiates an out-going data connection. This connection could be terminated by a host application at headquarters (HQ) or a remote web server (i.e., web browsing). Some carriers refer to this as mobile originated data. Another typical example of mobile originated data is a client-tosite VPN.
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