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I need to create a network which has 2 adsl connections with failover incase one goes down.

I'd prefer to have one primary adsl connection and one backup adsl connection which is only used if the master goes down.

I've seen someone else's implementation which included 2 adsl routers, a firewall server and a hub/switch which did load balancing between the 2 connections but load balancing is not required.

What hardware/software combination would be most cost effective and efficient?


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up vote 2 down vote accepted

For this sort of thing, If you want a pure off the shelf hardware solution that does not involve custom software or tinkering, I would recommend a Draytek router.

They work very well, typically it is a modem/router itself and has one standard ethernet port for failover, so you would connect an existing router into that and you can configure it for failover or bonding.

Drayteks are great, you can even plug in a 3g usb card to use when the connection fails!

Remember though, if you are doing this purely for resilience, having two ADSL connections may not "save" you. I am guessing that most countries would be similar to the UK, the connections will terminate at the same exchange so whilst having two connections will help against an ISP doing maintenance (If you pick two different ones), it will not prevent you from other "unplanned" problems that is responsible most of the time for disconnections.

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do the routers with the 3g USB socket do automatic failover to the 3g or would i have to manually switch over? – pstanton Jan 7 '10 at 3:53
It really depends on the router, on a clients Draytek, I am pretty sure I have it set so it will only use if the main line(s) go down, but I would need to double check. – William Hilsum Jan 7 '10 at 4:05
just talked to draytek - 2710 and 2820 do failover to 3g. cool! – pstanton Jan 7 '10 at 4:21

Why would you want the other DSL line on standby? You're paying for the line - using it or not. Load balancing would seem to be better economically unless you have some sort of bandwidth costs. Also, again if one DSL line goes dead, the other likely will as well since both are probably terminating at the same CO. Dependent on how much bandwidth you need - it may be possible that a router with automatic failover to a 3G/4G/WiMax card or USB stick might serve as well.

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failover because we could purchase one mid-high download limit account and one low download limit with 2 different providers. – pstanton Jan 7 '10 at 3:54

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