Dual ADSL for Added Redundancy

How do you protect against poor ADSL connections? You need Dual ADSL connections, for added redundancy. There comes a point when you no longer can rely on a single ADSL connection for your network. Things start getting too hectic through that one little connection running down some 100 year old copper pair, the modem freaks out and dies on a regular basis, and then people start screaming out for a fix.

It’s all too easy to become very reliant on your connection to the internet, and when it doesn’t work, everyone will find out pretty quickly. In a radio environment in particular, it just isn’t acceptable to have your news feed, internet streams and VoIP fail so frequently.

The fix is to order a second ADSL connection from a different provider, and to bond them together using some sort of load balancing hardware. That device needs to be smart enough to work out what both connections were doing, fix any issues, and route the traffic in the right direction. You need a router/firewall with dual-WAN ports.

One might expect to spend quite a large sum of money on a piece of hardware like this. But thankfully you don’t have to. There are plenty of options out there, such as the Draytek Vigor 2850. This little box can be purchased in the $300 range.

Setup with this unit is fairly simple. In fact, if you know the jargon of LANs, WANs, and all that jazz, it’s easy. If you don’t, then I suggest you learn that aspect of things before you buy this box. There’s defiantly an expectation that you aren’t a beginner when trying to set up this piece of hardware.

Configuration is via web interface, so you don’t need to learn the command line as you may with certain big-brand products.

To get your dual WAN load balancing working, you need to turn each of your two ADSL modems into ‘dumb’ modems. This means that the box which interfaces your phone line with the network dosen’t handle any sort of router functionality. In fact, it shouldn’t even handle any PPPoE authentication. The term used to describe this is ‘bridge mode’.

Once your modem is in bridge mode, the DrayTek Vigor 2850 handles all of the PPPoE authentication. The beauty of this arrangement is that if your modem disconnects, the DrayTek picks up on it really quickly, and it’s reconnected before you know it.

Setting up firewall rules and port forwarding is also fairly straight forward, and done in a similar fashion to ordinary modem/router devices, but with extra functionality. There is also load balancing policy, so you can choose certain services to go through certain WAN ports if that is desired. There are also features available such as URL-filtering, VPNs, and all that good stuff. Even if you don’t need all of these goodies right now, at least you know they are ready to go in the future if a need arises.

It’s also worth noting this particular model also has a USB port, so it is theoretically possible to connect a 3G or 4G modem to it and use this as the 2nd WAN connection instead of an ADSL connection. Check the specs though – not all modems are supported.

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I'm Anthony Eden, and I'm a IT Professional, Broadcast Technician, Software Developer, and Solutions Engineer. I've been working in broadcast media since 2008, and developing software and websites for just as long. Right now, I provide freelance services through Media Realm - in particular, to the media and not-for-profit industries.

Follow Anthony on Twitter: @anthony_eden