<html><head></head><body><div>On Thu, 2015-07-09 at 09:59 -0400, Derek Atkins wrote:</div><blockquote type="cite">However if you're just using NAT and trying to decide "hey, my main link<br>
is down, let me switch over to using NAT over the other link", then I'm<br>
afraid I don't know a good way to do that. You probably don't want to<br>
have this automated, because all your existing connections will break if<br>
that happens.<br></blockquote><div><br></div><div>The solution I've recommended in the past in that situation (commodity access without dynamic routing capability) is to take a single suitably-sized Linode system and use that as your network's IP address. Then have your NAT box create Tunnel A and Tunnel B to the Linode. Bond both of them such that they are load-balanced if the two connections are close enough in bandwith and latency to each other, or use only A or B based on availability, schedule, or whatever other criteria you wish.</div><div><br></div><div>It's simple(ish), and costs $ISP_COST + $20 per month.</div><div><br></div><div>Sans the Linode, deal with breakage of communications at failover, as there really isn't a way to move state like that unless you're using SCTP, and the Internet doesn't.</div></body></html>