--- a/extensions/rt_un_number/rtun.c	Wed Aug 25 19:00:25 2010 +0900
+++ b/extensions/rt_un_number/rtun.c	Thu Aug 26 14:10:03 2010 +0900
@@ -136,6 +136,13 @@
 	/* Parse the configuration file */
 	CHECK_FCT( rtun_conf_handle(conffile) );
 	
+	/* Check the configuration */
+	CHECK_PARAMS_DO( rtun_conf.serv_nb > 1,
+		{
+			fd_log_debug("[rt_un_number] Invalid configuration: you need at least 2 servers to perform load-balancing.\n");
+			return EINVAL;
+		} );
+	
 	/* Register the callback */
 	CHECK_FCT( fd_rt_out_register( rtun_out, NULL, 1, &rtun_hdl ) );