FreeBSD network failover

[Randy Bush]

On 08.12.16 18:56, Gabe wrote:
> I have a nat'd box which obviously has an internal and external ip
> address. The box has a third interface which is configured to a DSL
> connection. My goal is for that interface to be activated if the
> external side fails so that outbound traffic still flows. Any of you
> know of a way to accomplish this regardless of the type of failure.

what routing protocols are involved?

randy