[LARTC] two routes, non-permanent higher proiority

[Bob Beers]

Hi LARTC experts,

Can you help me with this scenario?  I have been
 lurking on this list for a while, but I am very green
 wrt advanced routing.

I have a slackware linux based server in a vehicle with
 a high bandwidth satellite connection which is only
 available while the vehicle is stationary.
This satellite connection comes in via eth0.  But while
 the vehicle is moving or stationary, we can use a
 CDMA modem via a ppp0 connection coming in on
 a serial port, but it is much lower bandwidth.

The vehicle operator should only need to park the
 vehicle, press the "engage the satellite" button, and
 as soon as the link is established, the satellite is
 the preferred path to the internet.

There will be traffic coming both from the router and
 from wired and wireless devices on private network.

Looking forward to your advice.

-Bob