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I'm setting up an offsite DR facility on a budget. The office has 2 ADSL lines coming in to identical router/modem devices.

I'm looking for a cost effective (cheap) way of joining the two connections so that the network only sees one link to the outside world.

Primarily I'm looking for ADSL failover as opposed to load balancing and bonding but if the solution does all theree then that's fine.

Is anyone aware of a device that does this, or alternatively software that could be installed on a PC with multiple NIC's to manage this sort of thing?

Thanks in advance.

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up vote 2 down vote accepted

Get a DrayTek 2955

Loads of feature for a one time price only

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Currently using a couple of 2820's for various things, didn't realise Draytek made exactly the device I was looking for. Thanks! – Marko Carter Aug 3 '10 at 13:52

You can install OpenBSD on old PC and use CARP (as Warner mentioned) or uCARP (for non-OpenBSD :).

I wanted to use two ADSL lines a year ago but provider dropped prices so I didn't accomplished this.

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I have a Syswan SW24 that I use for WAN failover and it works pretty well. I suspect the firmware has a memory leak because if I leave a bittorrent client running over the weekend, it'll lock up, but otherwise it runs for months without reboot given typical office usage.

pfsense, among other software options, does this, too.

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+1 pfsense looks excellent, especially as it's open source. Thanks for taking the time to answer. – Marko Carter Aug 3 '10 at 13:53

You are best off focusing on network protocols for your type of implementation.

Typically Border Gateway Protocol (BGP) is among the ideal solution for managing dynamic network routing but this is unlikely an option with your DSL connections. Nevertheless, this would be the first choice for different types of Internet connections.

Be aware of single points of failure. A single switch, cabling, all interfaces, and devices that are shared between your two connections. Consider all failure points and types of failure to eliminate risk where possible.

HSRP would be among your potential solutions. HSRP is a Cisco protocol but there are alternative implementations that can be implemented on Open Source operating systems, such as CARP or VRRP. You would want to track both the internal and external interfaces to attempt to mitigate a single point failing without failover.

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Have a look at Endian Community firewall. It allows multiple connections to be setup with failover. It's free, and also a solid firewall/proxy too.

Download the ISO and install on any old bit of hardware with multiple NICs.

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