diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index 14f0b33..1188d95 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -127,6 +127,13 @@
 
 	  If unsure, say Y.
 
+config INET6_XFRM_MODE_ROUTEOPTIMIZATION
+	tristate "IPv6: MIPv6 route optimization mode (EXPERIMENTAL)"
+	depends on IPV6 && EXPERIMENTAL
+	select XFRM
+	---help---
+	  Support for MIPv6 route optimization mode.
+
 config IPV6_TUNNEL
 	tristate "IPv6: IPv6-in-IPv6 tunnel"
 	select INET6_TUNNEL
diff --git a/net/ipv6/Makefile b/net/ipv6/Makefile
index 9eebf60..87e912e 100644
--- a/net/ipv6/Makefile
+++ b/net/ipv6/Makefile
@@ -23,6 +23,7 @@
 obj-$(CONFIG_INET6_TUNNEL) += tunnel6.o
 obj-$(CONFIG_INET6_XFRM_MODE_TRANSPORT) += xfrm6_mode_transport.o
 obj-$(CONFIG_INET6_XFRM_MODE_TUNNEL) += xfrm6_mode_tunnel.o
+obj-$(CONFIG_INET6_XFRM_MODE_ROUTEOPTIMIZATION) += xfrm6_mode_ro.o
 obj-$(CONFIG_NETFILTER)	+= netfilter/
 
 obj-$(CONFIG_IPV6_TUNNEL) += ip6_tunnel.o
diff --git a/net/ipv6/xfrm6_mode_ro.c b/net/ipv6/xfrm6_mode_ro.c
new file mode 100644
index 0000000..c11c335
--- /dev/null
+++ b/net/ipv6/xfrm6_mode_ro.c
@@ -0,0 +1,94 @@
+/*
+ * xfrm6_mode_ro.c - Route optimization mode for IPv6.
+ *
+ * Copyright (C)2003-2006 Helsinki University of Technology
+ * Copyright (C)2003-2006 USAGI/WIDE Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+/*
+ * Authors:
+ *	Noriaki TAKAMIYA @USAGI
+ *	Masahide NAKAMURA @USAGI
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/stringify.h>
+#include <net/ipv6.h>
+#include <net/xfrm.h>
+
+/* Add route optimization header space.
+ *
+ * The IP header and mutable extension headers will be moved forward to make
+ * space for the route optimization header.
+ *
+ * On exit, skb->h will be set to the start of the encapsulation header to be
+ * filled in by x->type->output and skb->nh will be set to the nextheader field
+ * of the extension header directly preceding the encapsulation header, or in
+ * its absence, that of the top IP header.  The value of skb->data will always
+ * point to the top IP header.
+ */
+static int xfrm6_ro_output(struct sk_buff *skb)
+{
+	struct xfrm_state *x = skb->dst->xfrm;
+	struct ipv6hdr *iph;
+	u8 *prevhdr;
+	int hdr_len;
+
+	skb_push(skb, x->props.header_len);
+	iph = skb->nh.ipv6h;
+
+	hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
+	skb->nh.raw = prevhdr - x->props.header_len;
+	skb->h.raw = skb->data + hdr_len;
+	memmove(skb->data, iph, hdr_len);
+	return 0;
+}
+
+/*
+ * Do nothing about routing optimization header unlike IPsec.
+ */
+static int xfrm6_ro_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	return 0;
+}
+
+static struct xfrm_mode xfrm6_ro_mode = {
+	.input = xfrm6_ro_input,
+	.output = xfrm6_ro_output,
+	.owner = THIS_MODULE,
+	.encap = XFRM_MODE_ROUTEOPTIMIZATION,
+};
+
+static int __init xfrm6_ro_init(void)
+{
+	return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
+}
+
+static void __exit xfrm6_ro_exit(void)
+{
+	int err;
+
+	err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
+	BUG_ON(err);
+}
+
+module_init(xfrm6_ro_init);
+module_exit(xfrm6_ro_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);