[ILUG-BOM] Backup Internet Line
raju at linux-delhi.org
Mon May 4 12:34:23 IST 2009
On Monday 04 May 2009, george at annamsoft.com wrote:
> I would like to have a backup internet connection to maintain a 100%
> up-time of the Internet.
> We want to achieve this by automatically switching between the
> internet links if it fails (i.e for eg. if the BSNL link goes off, it
> has to take the AIRTEL link and once the BSNL link is ready, it has
> to switch automatically to it.)
What is the equipment terminating the line?
If these are DSL lines, you can set up a Linux box that runs PPPoE for
all your links directly. Then it's trivial to be able to determine if
the link is up or not: if the PPP process of the link is up, you can
route through it. Run a small script that checks the link status every
minute and sets the default route according to which link is up.
NAT-ing on this Linux box will allow the rest of your LAN to access
If you're running proper routers for each link, you'll need to write a
slightly longer script that will check transmission through each router
and set the default gateway depending on which router is letting
transmissions through. Again, NAT your LAN traffic through the Linux
box that does this.
You can also load balance between multiple links using Linux if you're
Raj Mathur raju at kandalaya.org http://kandalaya.org/
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