While editing a route, click Auto
Route 
(Routing Tools toolbar) or click Routing,
Routing Tools, Auto
Route.
Set options in the Auto Route PropertyManager:
Click 
.
Auto Route enables you to:
Route automatically through existing geometry in the 3D route sketch.
Route automatically through certain objects that are outside the route sketch.
Update routes to travel through selected clips.
Display guidelines that show wires from imported from/to data, manipulate those guidelines, and convert them into routes.
To route automatically:
While editing a route, click Auto
Route (Routing Tools toolbar) or click Routing,
Routing Tools, Auto
Route.
Set options in the Auto Route PropertyManager:
Click .
You can also route automatically by dropping
cable clips
in the route.