diff --git a/include/linux/if_tunnel.h b/include/linux/if_tunnel.h
index 5a9aae4adb444a3c8a63b5b9c5afd2c4456396de..5eb9b0f857e0720569eb04373ef42fb51bb04c9a 100644
--- a/include/linux/if_tunnel.h
+++ b/include/linux/if_tunnel.h
@@ -44,7 +44,7 @@ struct ip_tunnel_prl {
 	__u16			flags;
 	__u16			__reserved;
 	__u32			datalen;
-	__u32			__reserved2;
+	__u32			rs_delay;
 	/* data follows */
 };
 
diff --git a/include/net/ipip.h b/include/net/ipip.h
index fdf9bd7437057e26b0f9cd3bdadb8c70ed8a09f6..5d3036fa1511695879a18d3adc02f57feef49392 100644
--- a/include/net/ipip.h
+++ b/include/net/ipip.h
@@ -28,11 +28,18 @@ struct ip_tunnel
 	unsigned int			prl_count;	/* # of entries in PRL */
 };
 
+/* ISATAP: default interval between RS in secondy */
+#define IPTUNNEL_RS_DEFAULT_DELAY	(900)
+
 struct ip_tunnel_prl_entry
 {
 	struct ip_tunnel_prl_entry	*next;
 	__be32				addr;
 	u16				flags;
+	unsigned long			rs_delay;
+	struct timer_list		rs_timer;
+	struct ip_tunnel		*tunnel;
+	spinlock_t			lock;
 };
 
 #define IPTUNNEL_XMIT() do {						\
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index ab65cc51b00e4953687c21497d586eda92eb12ac..e09f12ee57cf956f5f68fb723c9b603954b20fa2 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -658,6 +658,7 @@ void ndisc_send_rs(struct net_device *dev, const struct in6_addr *saddr,
 		     &icmp6h, NULL,
 		     send_sllao ? ND_OPT_SOURCE_LL_ADDR : 0);
 }
+EXPORT_SYMBOL(ndisc_send_rs);
 
 
 static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 3fd060076e7a78bad437041f2a5c1cca0322ac86..b3a59bd40f0184a7bad41d6b4320263040086659 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -15,6 +15,7 @@
  * Roger Venning <r.venning@telstra.com>:	6to4 support
  * Nate Thompson <nate@thebog.net>:		6to4 support
  * Fred Templin <fred.l.templin@boeing.com>:	isatap support
+ * Sascha Hlusiak <mail@saschahlusiak.de>:	stateless autoconf for isatap
  */
 
 #include <linux/module.h>
@@ -222,6 +223,44 @@ static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
 	return NULL;
 }
 
+static void ipip6_tunnel_rs_timer(unsigned long data)
+{
+	struct ip_tunnel_prl_entry *p = (struct ip_tunnel_prl_entry *) data;
+	struct inet6_dev *ifp;
+	struct inet6_ifaddr *addr;
+
+	spin_lock(&p->lock);
+	ifp = __in6_dev_get(p->tunnel->dev);
+
+	read_lock_bh(&ifp->lock);
+	for (addr = ifp->addr_list; addr; addr = addr->if_next) {
+		struct in6_addr rtr;
+
+		if (!(ipv6_addr_type(&addr->addr) & IPV6_ADDR_LINKLOCAL))
+			continue;
+
+		/* Send RS to guessed linklocal address of router
+		 *
+		 * Better: send to ff02::2 encapsuled in unicast directly
+		 * to router-v4 instead of guessing the v6 address.
+		 *
+		 * Cisco/Windows seem to not set the u/l bit correctly,
+		 * so we won't guess right.
+		 */
+		ipv6_addr_set(&rtr,  htonl(0xFE800000), 0, 0, 0);
+		if (!__ipv6_isatap_ifid(rtr.s6_addr + 8,
+					p->addr)) {
+			ndisc_send_rs(p->tunnel->dev, &addr->addr, &rtr);
+		}
+	}
+	read_unlock_bh(&ifp->lock);
+
+	mod_timer(&p->rs_timer, jiffies + HZ * p->rs_delay);
+	spin_unlock(&p->lock);
+
+	return;
+}
+
 static struct ip_tunnel_prl_entry *
 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 {
@@ -280,6 +319,7 @@ static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 			continue;
 		kp[c].addr = prl->addr;
 		kp[c].flags = prl->flags;
+		kp[c].rs_delay = prl->rs_delay;
 		c++;
 		if (kprl.addr != htonl(INADDR_ANY))
 			break;
@@ -329,11 +369,23 @@ ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 	}
 
 	p->next = t->prl;
+	p->tunnel = t;
 	t->prl = p;
 	t->prl_count++;
+
+	spin_lock_init(&p->lock);
+	setup_timer(&p->rs_timer, ipip6_tunnel_rs_timer, (unsigned long) p);
 update:
 	p->addr = a->addr;
 	p->flags = a->flags;
+	p->rs_delay = a->rs_delay;
+	if (p->rs_delay == 0)
+		p->rs_delay = IPTUNNEL_RS_DEFAULT_DELAY;
+	spin_lock(&p->lock);
+	del_timer(&p->rs_timer);
+	if (p->flags & PRL_DEFAULT)
+		mod_timer(&p->rs_timer, jiffies + 1);
+	spin_unlock(&p->lock);
 out:
 	write_unlock(&ipip6_lock);
 	return err;
@@ -352,6 +404,9 @@ ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 			if ((*p)->addr == a->addr) {
 				x = *p;
 				*p = x->next;
+				spin_lock(&x->lock);
+				del_timer(&x->rs_timer);
+				spin_unlock(&x->lock);
 				kfree(x);
 				t->prl_count--;
 				goto out;
@@ -362,6 +417,9 @@ ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 		while (t->prl) {
 			x = t->prl;
 			t->prl = t->prl->next;
+			spin_lock(&x->lock);
+			del_timer(&x->rs_timer);
+			spin_unlock(&x->lock);
 			kfree(x);
 			t->prl_count--;
 		}