ASP.网络路线和cms

我已经设法得到友好的url与我的cms工作;然而，我想知道的是:与asp.net 4.0路由选项，我如何得到一个根离开路由?当用户输入www.mysite.com/page_name，这是关于我们的，它会转到页面cms。Aspx，但保留其他路由完整:

        routes.Clear();
        // Register a route for Products/{ProductName}
        routes.MapPageRoute(
            "View Product",             // Route name
            "Products/{ProductName}",   // Route URL
            "~/products.aspx"        // Web page to handle route
        );

        // Register a route for Products/{ProductName}
        routes.MapPageRoute(
            "ShoppingCart",       // Route name
            "{ShoppingCart}",   // Route URL
            "~/Basket.aspx"        // Web page to handle route
        );

        // Register a route for Products/{ProductName}
        routes.MapPageRoute(
            "ShoppingCart",       // Route name
            "{ShoppingCart}",   // Route URL
            "~/Basket.aspx"        // Web page to handle route
        );
  // --->> How do i do this
  // Register a route for url/{pagename}
        routes.MapPageRoute(
            "cms",       // Route name
            "{}",   // Route URL
            "~/cms.aspx"        // Web page to handle route
        );