It’s not uncommon to see on many offices that the Internet connection comes from several WAN connections (for redundancy, or whatever). Even on the more freak homes I’ve seen a multiwan setup (i.e., one wan from the ISP, other from a guifi.net vpn, and other wan being stolen from the neighbors).
I know three methods for managing automatically more than one WAN connection. Best yet, automatically but meeting several rules (i.e.: youtube transit sent to wan1, bittorrent to wan2 and HTTPS transit to wan3).
Method 1: RouterOS PCC
Mikrotik routers can handle natively a multiwan setup through PCC (Per Connection Classifier). Packets must be marked with a routing mark and then the PCC chosses where to send them. Best references:
- Balanceo de Carga PCC de 2, 3, 4 o más líneas de Internet con Mikrotik (by Ryohnosuke)
Method 2: OpenWRT MWAN3
MWAN3 is a package for OpenWRT that do the job and can be configured in a easy and visual way. So you need a powerful router fully compatible with OpenWRT and MWAN3. I have an ex-coworker that uses this stuff and wrote this excellent post:
Method 3: Linux
Method 1 and 2 requires a special router, but this method only requires a Linux Box with two or more ethernet cards. I’ve not tested it but it seems very interesting because it’s not hardware-dependant. In fact, that software is designed for, given more than one WAN connection, discard the first that gets disconnected (hence the title of the project).