Modem Gateway Router, What Is The Difference?


Shared on October 10, 2012 written by Keith McRae

M2M modem, M2M gateway, and M2M router or wireless modem, wireless gateway, and wireless router are terms often used interchangeably.

The most common term, M2M Modem, is generally the least accurate because it is a very broad term coming from its days when acoustically coupled MOdulator DEModulator (MO-DEM) devices converted data signals to fit the transport medium available (POTS lines). An M2M modem, strictly speaking an M2M Radio Modem, would not have much device level intelligence, hence the proliferation of terms for more sophisticated devices being referred to as intelligent wireless gateways and intelligent wireless routers. Devices with no routing capabilities, which run on AT commands and have no local sophisticated Operating System or OS, are the most like an M2M modemĚ.

Today, wireless modem, is a generic term that refers to essentially all radio connection devices for cellular, satellite, private radio, and 802.11x wireless networks. Everything from wireless routers, to Cisco HWIC cards, to USB stick modems, to Sprint Overdrive and Verizon WiFi units, to Sierra Wireless Ravens and Cisco Aeronet WiFi devices. These are all generally referred to as wireless modems, albeit this is a sweeping one-size-fits-all category.

M2M gateways or intelligent wireless gateways such as the Airlink Raven X work in the cellular radio space and add intelligence and routing to the activity of connecting a device to the internet. They will translate a private local IP to a public network IP assigned by the cellular service carrier. They can provide VPN tunnels, modem level password security, keep alive pings, automatic timed restarts, Network Time Protocol updates from US atomic clocks, and IP block and IP white (friendly IP) lists "these features are some of the intelligence in intelligent gateways. They can also have some routing capabilities, although these will not be as robust as an intelligent wireless router. Often, M2M gateways involve one-to-one or one-to-few connections. The gateway connects a local private device or local private network to the internet. These are sometimes considered, intelligent modems.

M2M routers or intelligent wireless routers such as the Digi Transport and Sierra Wireless GX-440 perform all the functions of a wireless gateway, but often add sophisticated routing capabilities and these are often present across multiple Ethernet and WLAN connections. These capabilities involve port forwarding or mapping and port routing, something USAT engineers spend time designing and refining for our clientele. The single public IP assigned from the carrier may be mapped in the M2M router so that 1 'port' of the single public IP is mapped to a camera, other to a sensor, and other to manage the M2M router, and another to a locally connected network for web access. Some M2M routers can also aggregate data collected from local wireless sensor networks such as those running over 'open' sensor networks such as ZigBee, 6LoWPAN, DASH7, BlueTooth or 'proprietary' networks such as DigiMesh, Xbee and Xbee Pro (Digi International's former MaxStream product).

Although there are technical differences between modem, M2M gateway, M2M router, wireless modem, wireless gateway, and wireless router, the terms are often used interchangeably. The best option is to let USAT navigate platform and device differentiation as it applies to your needs.

As an afterthought, we are seeing devices support more robust programming and scripting languages within the intelligent modem/gateway/router. Digi International supports the Python language in numerous platforms, and Sierra Wireless support LUA based programming. These programs tap into the device level intelligence, and let USAT software engineers develop decision gates at the device level. These local decisions cut down on network traffic, as the modem does the 'analysis. An example would be to 'instruct' the gateway to 'watch' the I/O trigger port for a state change, such as a bus door opening. When the door opens, have the gateway turn on a light locally, and send the GPS coordinates to the cloud with the door state.

These devices step up 'modem' capabilities and launch a class of programmable intelligent gateways.

Keywords: M2M Terms

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