inter switch connection

Hi all,

I am fairly new to setting up switches and need some advice on how to configure links between switches. I have a flat layer 2 network in building 1 with a 6248 switch acting as a core switch and a 6224 in building 2. The two buildings are connected together via a 1GB laser link and a 100MB RF link; the laser is the primary link and is plugged in all the time in building 1, the cable for the RF link is left unplugged. In building 2 both cables are plugged in.

When the laser link fails (thick fog and snow !) we have to manually unplug the laser in building 1 and plug in the RF link. I would like to configure the switches to automatically fail between the links without having to manually plug in cables.

I assume this is done using STP but I am not sure how to configure this to avoid a routing loop - any help would be greatly appreciated.

Thanks,