--- a/sim/defconfig	Thu Feb 09 13:34:55 2012 +0100
+++ b/sim/defconfig	Thu Jun 21 16:29:32 2012 +0900
@@ -87,7 +87,7 @@
 # CONFIG_DEFAULT_WESTWOOD is not set
 CONFIG_DEFAULT_RENO=y
 CONFIG_DEFAULT_TCP_CONG="reno"
-CONFIG_IPV6=m
+CONFIG_IPV6=y
 CONFIG_IPV6_PRIVACY=y
 CONFIG_IPV6_ROUTER_PREF=y
 CONFIG_INET6_AH=m