Somebody explain to me the general idea behind Internet Connectivity Failover. SBC knocked out our DSL service for 10 days! The owners are fed up with it and want to make sure this never happens again. They want to have a second connection via another ISP. While both lines are working I guess it would be nice to have load-balancing too to get the full benefit. I'm looking for solutions that do not necessarily have to have a Linux based answer. What equipment is needed? Any help to point me in the right direction would be great!

TIA,

The provider seems to belong to the "cheapest mainstream" - this what i assume from the fact that they "provide" downtimes of more than a day! If the line is "business critical", spending a bit more money into a more sophisticated provider could help.

Everything you can do to achieve ISP failover depends on the site's size (amount of computers and users) and on the budget.

One option:
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Plug 2 in a 2nd modem and configure it for the 2nd provider.
Connect both modems to one "server" (i386/166 is sufficient when using linux).

Write a simple script (using "bash", "perl", "phyton" or ruby) that will check the connection to the internet using the default route. If it the connection does not succeed, the script should change the default route leading through the 2nd DSL-modem.
Use "cron" to call the script every 1 to 5 minutes.


Another option (more to know and to adjust for this):
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- 2 DSL-Modem/Routers connected towards one HUB.
- 1 Router (Dedicated product or Linux system or W2K/XP)
having 2 network cards.
One card is connected to the HUB mentioned above,
the other card is connected to the "internal LAN".

Using this infrastructure, one can configure "routing protocols" (e.g. BGP, EGP, ...) on the router that will figure out accessible routes to the internet automatically. In addition, "QoS" mimics (quality of service) can be configured to dedicate specific amounts of bandwith to specific hosts and/or services.

Implementing multiple gateways between intranet and internet might be somewhat too challenging for the unexperienced. Nevertheless it can be fun after the learning curve flattens ...
;-)

Thanks for your response. On this, there will be some type of budget, so I'd like to get the most professional solution possible. I've read a little about dual WAN or multihomed router appliances. Anybody have a suggestion or opinion about them?