Double NAT, does this affect you?

I know, another computer term and why should you care about it? Double NAT is something that occurs more regularly than businesses and people are aware of and the reason you should care – Double NAT slows internet speed and makes the Internet unreliable at best.

NAT is Network Address Translation, in layman terms; NAT assigns routes to IP (Internet Protocol) addresses (192.168.0.x), just like the Post Office assigning a carrier to deliver your mail. The device that handles the NAT is a physical device called a Router. A router can be packaged as a standalone product or incorporated with another device, such as a modem, gateway and so forth. The picture shown utilizes separate components to illustrate the simplest form for NAT responsibilities.

Note again, the picture is using separate components because now it’s going to get convoluted. A modem that you get from your ISP (Internet Service Provider) can come with a router built into it. This means you’ll need to be aware of what devices are attached to the modem/router. If you attach another device (such as a router/switch or a wireless router, etc…), into the configuration with routing capabilities you have just created a double NAT situation. This will create an unreliable Internet connection if the devices aren’t setup properly. Guess what, your ISP isn’t responsible for this issue either. The ISP’s responsibility is to make sure that a single computer can connect directly through their equipment, anything beyond that is taken care of by the generosity of the technician or is your responsibility.

Double NAT circumstances do function, however it creates much frustration. What’s created in a Double NAT situation is two controlling devices trying to tell your computers and other devices what their addresses are and where to send information. Have you ever been in an environment where you have two people giving directions of how, what, when, where and why and the directions are in direct conflict with each other? To quote the movie Office Space for a better illustration; “We don’t have a lot of time on this earth. We weren’t meant to spend it this way. Human beings were not meant to sit in little cubicles staring at computer screens all day, filling out useless forms and listening to eight different bosses drone on about mission statements.” This is exactly what multiple routers become and sometimes it works, most of the time it doesn’t or it doesn’t work very well. And remember, it’s not your ISP’s issue because they only verify that you have a direct connection to the Internet through their equipment and will show no problem.

The double NAT circumstance is avoidable even if you do have two router capable devices. One router will need to be put into bridge mode manually. Ideally, you should only have one device in your configuration with the capability of routing for the needs of your network. If you’re concerned you may have a double NAT happening at your place of business or home get a qualified tech in there to get you back down to just one boss calling the shots.


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