Backup paths to the internet.

[Kipton Moravec]

I am planning to use a computer as a gateway/firewall running Ubuntu (or
another version of Linux).

What is the utility, or service, I need to allow different paths to the
Internet through this gateway?

For example, the primary path to the Internet is through eth0 the first
Ethernet card in the computer.  However if that gateway is down, then I
want it to use a second path (or a third if #2 is down also). I can make
it another card (eth1), or another IP address on the first card. Finally
if all else fails, I would want it to dial up (or use a serial port) to
establish a slow but functioning connection.

When the first path is active again it goes back to the original
configuration. 

I want this to happen at the gateway computer, so the users do not see
anything, except for a reduction in performance if I go to a slower
connection.

What is this called, and what do I have to read up on? 
It is more than just IP Tables right?

Kip
-- 


Kipton Moravec AE5IB .- . ..... .. -... 
==============================================
Four Way Test
Is it the Truth?
Is it Fair to all concerned?
Will it build Goodwill and Better Friendships?
Will it be Beneficial to all concerned?
- Herbert J Taylor (1932)