routing_dev.yml:
    ... 
    _main:
        resource: routing.yml
    ....


routing.yml:
    ....
    WebSiteCategoryBundle:
       resource: "@WebSiteCategoryBundle/Controller/"
       type:     annotation
       prefix:   /    
   ....


src/WebSite/CategoryBundle/CategoryController.php:

    /**
    * @Route("/catalog")
    */
    class CategoryController extends Controller
    {

        /**
         * @Route("/{alias}", name="show_category" )
         * @Template()
         */
        public function showAction( $alias )
        {
          // some action here
        }
    }