diff --git a/include/linux/if_addr.h b/include/linux/if_addr.h
index d557e4c..43f3bed 100644
--- a/include/linux/if_addr.h
+++ b/include/linux/if_addr.h
@@ -39,6 +39,7 @@
 #define IFA_F_TEMPORARY		IFA_F_SECONDARY
 
 #define	IFA_F_NODAD		0x02
+#define IFA_F_OPTIMISTIC	0x04
 #define	IFA_F_HOMEADDRESS	0x10
 #define IFA_F_DEPRECATED	0x20
 #define IFA_F_TENTATIVE		0x40
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 713eb5e..e046b22 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -178,6 +178,9 @@
 #endif
 	__s32		proxy_ndp;
 	__s32		accept_source_route;
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	__s32		optimistic_dad;
+#endif
 	void		*sysctl;
 };
 
@@ -208,6 +211,7 @@
 	DEVCONF_PROXY_NDP,
 	__DEVCONF_OPTIMISTIC_DAD,
 	DEVCONF_ACCEPT_SOURCE_ROUTE,
+	DEVCONF_OPTIMISTIC_DAD,
 	DEVCONF_MAX
 };
 
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 88df8fc..f3531d0 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -73,7 +73,9 @@
 extern int			ipv6_dev_get_saddr(struct net_device *dev, 
 					       struct in6_addr *daddr,
 					       struct in6_addr *saddr);
-extern int			ipv6_get_lladdr(struct net_device *dev, struct in6_addr *);
+extern int			ipv6_get_lladdr(struct net_device *dev,
+						struct in6_addr *addr,
+						unsigned char banned_flags);
 extern int			ipv6_rcv_saddr_equal(const struct sock *sk, 
 						      const struct sock *sk2);
 extern void			addrconf_join_solict(struct net_device *dev,
diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index 79682ef..8e5d54f 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -57,6 +57,16 @@
 
 	  If unsure, say N.
 
+config IPV6_OPTIMISTIC_DAD
+	bool "IPv6: Enable RFC 4429 Optimistic DAD (EXPERIMENTAL)"
+	depends on IPV6 && EXPERIMENTAL
+	---help---
+	  This is experimental support for optimistic Duplicate
+	  Address Detection.  It allows for autoconfigured addresses
+	  to be used more quickly.
+
+	  If unsure, say N.
+
 config INET6_AH
 	tristate "IPv6: AH transformation"
 	depends on IPV6
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e035896..38274c2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -530,6 +530,16 @@
 
 	ifa->rt = rt;
 
+	/*
+	 * part one of RFC 4429, section 3.3
+	 * We should not configure an address as
+	 * optimistic if we do not yet know the link
+	 * layer address of our nexhop router
+	 */
+
+	if (rt->rt6i_nexthop == NULL)
+		ifa->flags &= ~IFA_F_OPTIMISTIC;
+
 	ifa->idev = idev;
 	in6_dev_hold(idev);
 	/* For caller */
@@ -706,6 +716,7 @@
 	int tmp_plen;
 	int ret = 0;
 	int max_addresses;
+	u32 addr_flags;
 
 	write_lock(&idev->lock);
 	if (ift) {
@@ -763,10 +774,17 @@
 	spin_unlock_bh(&ifp->lock);
 
 	write_unlock(&idev->lock);
+
+	addr_flags = IFA_F_TEMPORARY;
+	/* set in addrconf_prefix_rcv() */
+	if (ifp->flags & IFA_F_OPTIMISTIC)
+		addr_flags |= IFA_F_OPTIMISTIC;
+
 	ift = !max_addresses ||
 	      ipv6_count_addresses(idev) < max_addresses ?
 		ipv6_add_addr(idev, &addr, tmp_plen,
-			      ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK, IFA_F_TEMPORARY) : NULL;
+			      ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK,
+			      addr_flags) : NULL;
 	if (!ift || IS_ERR(ift)) {
 		in6_ifa_put(ifp);
 		in6_dev_put(idev);
@@ -898,13 +916,14 @@
 			 * - Tentative Address (RFC2462 section 5.4)
 			 *  - A tentative address is not considered
 			 *    "assigned to an interface" in the traditional
-			 *    sense.
+			 *    sense, unless it is also flagged as optimistic.
 			 * - Candidate Source Address (section 4)
 			 *  - In any case, anycast addresses, multicast
 			 *    addresses, and the unspecified address MUST
 			 *    NOT be included in a candidate set.
 			 */
-			if (ifa->flags & IFA_F_TENTATIVE)
+			if ((ifa->flags & IFA_F_TENTATIVE) &&
+			    (!(ifa->flags & IFA_F_OPTIMISTIC)))
 				continue;
 			if (unlikely(score.addr_type == IPV6_ADDR_ANY ||
 				     score.addr_type & IPV6_ADDR_MULTICAST)) {
@@ -963,15 +982,17 @@
 				}
 			}
 
-			/* Rule 3: Avoid deprecated address */
+			/* Rule 3: Avoid deprecated and optimistic addresses */
 			if (hiscore.rule < 3) {
 				if (ipv6_saddr_preferred(hiscore.addr_type) ||
-				    !(ifa_result->flags & IFA_F_DEPRECATED))
+				   (((ifa_result->flags &
+				    (IFA_F_DEPRECATED|IFA_F_OPTIMISTIC)) == 0)))
 					hiscore.attrs |= IPV6_SADDR_SCORE_PREFERRED;
 				hiscore.rule++;
 			}
 			if (ipv6_saddr_preferred(score.addr_type) ||
-			    !(ifa->flags & IFA_F_DEPRECATED)) {
+			   (((ifa_result->flags &
+			    (IFA_F_DEPRECATED|IFA_F_OPTIMISTIC)) == 0))) {
 				score.attrs |= IPV6_SADDR_SCORE_PREFERRED;
 				if (!(hiscore.attrs & IPV6_SADDR_SCORE_PREFERRED)) {
 					score.rule = 3;
@@ -1111,7 +1132,8 @@
 
 EXPORT_SYMBOL(ipv6_get_saddr);
 
-int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr)
+int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr,
+		    unsigned char banned_flags)
 {
 	struct inet6_dev *idev;
 	int err = -EADDRNOTAVAIL;
@@ -1122,7 +1144,7 @@
 
 		read_lock_bh(&idev->lock);
 		for (ifp=idev->addr_list; ifp; ifp=ifp->if_next) {
-			if (ifp->scope == IFA_LINK && !(ifp->flags&IFA_F_TENTATIVE)) {
+			if (ifp->scope == IFA_LINK && !(ifp->flags & banned_flags)) {
 				ipv6_addr_copy(addr, &ifp->addr);
 				err = 0;
 				break;
@@ -1674,6 +1696,13 @@
 
 		if (ifp == NULL && valid_lft) {
 			int max_addresses = in6_dev->cnf.max_addresses;
+			u32 addr_flags = 0;
+
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+			if (in6_dev->cnf.optimistic_dad &&
+			    !ipv6_devconf.forwarding)
+				addr_flags = IFA_F_OPTIMISTIC;
+#endif
 
 			/* Do not allow to create too much of autoconfigured
 			 * addresses; this would be too easy way to crash kernel.
@@ -1681,7 +1710,8 @@
 			if (!max_addresses ||
 			    ipv6_count_addresses(in6_dev) < max_addresses)
 				ifp = ipv6_add_addr(in6_dev, &addr, pinfo->prefix_len,
-						    addr_type&IPV6_ADDR_SCOPE_MASK, 0);
+						    addr_type&IPV6_ADDR_SCOPE_MASK,
+						    addr_flags);
 
 			if (!ifp || IS_ERR(ifp)) {
 				in6_dev_put(in6_dev);
@@ -1889,6 +1919,11 @@
 
 		addrconf_prefix_route(&ifp->addr, ifp->prefix_len, dev,
 				      jiffies_to_clock_t(valid_lft * HZ), flags);
+		/*
+		 * Note that section 3.1 of RFC 4429 indicates
+		 * that the Optimistic flag should not be set for
+		 * manually configured addresses
+		 */
 		addrconf_dad_start(ifp, 0);
 		in6_ifa_put(ifp);
 		addrconf_verify(0);
@@ -2065,8 +2100,16 @@
 static void addrconf_add_linklocal(struct inet6_dev *idev, struct in6_addr *addr)
 {
 	struct inet6_ifaddr * ifp;
+	u32 addr_flags = IFA_F_PERMANENT;
 
-	ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, IFA_F_PERMANENT);
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	if (idev->cnf.optimistic_dad &&
+	    !ipv6_devconf.forwarding)
+		addr_flags |= IFA_F_OPTIMISTIC;
+#endif
+
+
+	ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, addr_flags);
 	if (!IS_ERR(ifp)) {
 		addrconf_prefix_route(&ifp->addr, ifp->prefix_len, idev->dev, 0, 0);
 		addrconf_dad_start(ifp, 0);
@@ -2134,7 +2177,7 @@
 {
 	struct in6_addr lladdr;
 
-	if (!ipv6_get_lladdr(link_dev, &lladdr)) {
+	if (!ipv6_get_lladdr(link_dev, &lladdr, IFA_F_TENTATIVE)) {
 		addrconf_add_linklocal(idev, &lladdr);
 		return 0;
 	}
@@ -2479,7 +2522,11 @@
 	unsigned long rand_num;
 	struct inet6_dev *idev = ifp->idev;
 
-	rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
+	if (ifp->flags & IFA_F_OPTIMISTIC)
+		rand_num = 0;
+	else
+		rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
+
 	ifp->probes = idev->cnf.dad_transmits;
 	addrconf_mod_timer(ifp, AC_DAD, rand_num);
 }
@@ -2501,7 +2548,7 @@
 	if (dev->flags&(IFF_NOARP|IFF_LOOPBACK) ||
 	    !(ifp->flags&IFA_F_TENTATIVE) ||
 	    ifp->flags & IFA_F_NODAD) {
-		ifp->flags &= ~IFA_F_TENTATIVE;
+		ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC);
 		spin_unlock_bh(&ifp->lock);
 		read_unlock_bh(&idev->lock);
 
@@ -2521,6 +2568,14 @@
 		addrconf_dad_stop(ifp);
 		return;
 	}
+
+	/*
+	 * Optimistic nodes can start receiving
+	 * Frames right away
+	 */
+	if(ifp->flags & IFA_F_OPTIMISTIC)
+		ip6_ins_rt(ifp->rt);
+
 	addrconf_dad_kick(ifp);
 	spin_unlock_bh(&ifp->lock);
 out:
@@ -2545,7 +2600,7 @@
 		 * DAD was successful
 		 */
 
-		ifp->flags &= ~IFA_F_TENTATIVE;
+		ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC);
 		spin_unlock_bh(&ifp->lock);
 		read_unlock_bh(&idev->lock);
 
@@ -3364,6 +3419,9 @@
 #endif
 	array[DEVCONF_PROXY_NDP] = cnf->proxy_ndp;
 	array[DEVCONF_ACCEPT_SOURCE_ROUTE] = cnf->accept_source_route;
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	array[DEVCONF_OPTIMISTIC_DAD] = cnf->optimistic_dad;
+#endif
 }
 
 static inline size_t inet6_if_nlmsg_size(void)
@@ -3578,7 +3636,14 @@
 
 	switch (event) {
 	case RTM_NEWADDR:
-		ip6_ins_rt(ifp->rt);
+		/*
+		 * If the address was optimistic
+		 * we inserted the route at the start of
+		 * our DAD process, so we don't need
+		 * to do it again
+		 */
+		if (!(ifp->rt->rt6i_node))
+			ip6_ins_rt(ifp->rt);
 		if (ifp->idev->cnf.forwarding)
 			addrconf_join_anycast(ifp);
 		break;
@@ -3899,6 +3964,17 @@
 			.mode		=	0644,
 			.proc_handler	=	&proc_dointvec,
 		},
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+		{
+			.ctl_name	=	CTL_UNNUMBERED,
+			.procname       =       "optimistic_dad",
+			.data           =       &ipv6_devconf.optimistic_dad,
+			.maxlen         =       sizeof(int),
+			.mode           =       0644,
+			.proc_handler   =       &proc_dointvec,
+
+		},
+#endif
 		{
 			.ctl_name	=	0,	/* sentinel */
 		}
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 0d60fbc..7e25043 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -863,6 +863,41 @@
 			goto out_err_release;
 	}
 
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+		/*
+		 * Here if the dst entry we've looked up
+		 * has a neighbour entry that is in the INCOMPLETE
+		 * state and the src address from the flow is
+		 * marked as OPTIMISTIC, we release the found
+		 * dst entry and replace it instead with the
+		 * dst entry of the nexthop router
+		 */
+		if (!((*dst)->neighbour->nud_state & NUD_VALID)) {
+			struct inet6_ifaddr *ifp;
+			struct flowi fl_gw;
+			int redirect;
+
+			ifp = ipv6_get_ifaddr(&fl->fl6_src, (*dst)->dev, 1);
+
+			redirect = (ifp && ifp->flags & IFA_F_OPTIMISTIC);
+			if (ifp)
+				in6_ifa_put(ifp);
+
+			if (redirect) {
+				/*
+				 * We need to get the dst entry for the
+				 * default router instead
+				 */
+				dst_release(*dst);
+				memcpy(&fl_gw, fl, sizeof(struct flowi));
+				memset(&fl_gw.fl6_dst, 0, sizeof(struct in6_addr));
+				*dst = ip6_route_output(sk, &fl_gw);
+				if ((err = (*dst)->error))
+					goto out_err_release;
+			}
+		}
+#endif
+
 	return 0;
 
 out_err_release:
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index a8d6625..924e249 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1411,7 +1411,7 @@
 
 	skb_reserve(skb, LL_RESERVED_SPACE(dev));
 
-	if (ipv6_get_lladdr(dev, &addr_buf)) {
+	if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) {
 		/* <draft-ietf-magma-mld-source-05.txt>:
 		 * use unspecified address as the source address
 		 * when a valid link-local address is not available.
@@ -1791,7 +1791,7 @@
 
 	skb_reserve(skb, LL_RESERVED_SPACE(dev));
 
-	if (ipv6_get_lladdr(dev, &addr_buf)) {
+	if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) {
 		/* <draft-ietf-magma-mld-source-05.txt>:
 		 * use unspecified address as the source address
 		 * when a valid link-local address is not available.
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 886c5be..b79b000 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -449,6 +449,8 @@
 	ifp = ipv6_get_ifaddr(solicited_addr, dev, 1);
 	if (ifp) {
 		src_addr = solicited_addr;
+		if (ifp->flags & IFA_F_OPTIMISTIC)
+			override = 0;
 		in6_ifa_put(ifp);
 	} else {
 		if (ipv6_dev_get_saddr(dev, daddr, &tmpaddr))
@@ -544,7 +546,8 @@
 	int send_llinfo;
 
 	if (saddr == NULL) {
-		if (ipv6_get_lladdr(dev, &addr_buf))
+		if (ipv6_get_lladdr(dev, &addr_buf,
+				   (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))
 			return;
 		saddr = &addr_buf;
 	}
@@ -624,9 +627,33 @@
 	struct sk_buff *skb;
 	struct icmp6hdr *hdr;
 	__u8 * opt;
+	struct inet6_ifaddr *ifp;
+	int send_sllao = dev->addr_len;
 	int len;
 	int err;
 
+
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	/*
+	 * According to section 2.2 of RFC 4429, we must not
+	 * send router solicitations with a sllao from
+	 * optimistic addresses, but we may send the solicitation
+	 * if we don't include the sllao.  So here we check
+	 * if our address is optimistic, and if so, we
+	 * supress the inclusion of the sllao.
+	 */
+	if (send_sllao) {
+		ifp = ipv6_get_ifaddr(saddr, dev, 1);
+		if (ifp) {
+			if (ifp->flags & IFA_F_OPTIMISTIC)  {
+				send_sllao=0;
+				in6_ifa_put(ifp);
+			}
+		} else {
+			send_sllao = 0;
+		}
+	}
+#endif
 	ndisc_flow_init(&fl, NDISC_ROUTER_SOLICITATION, saddr, daddr,
 			dev->ifindex);
 
@@ -639,7 +666,7 @@
 		return;
 
 	len = sizeof(struct icmp6hdr);
-	if (dev->addr_len)
+	if (send_sllao)
 		len += ndisc_opt_addr_space(dev);
 
 	skb = sock_alloc_send_skb(sk,
@@ -666,7 +693,7 @@
 
 	opt = (u8*) (hdr + 1);
 
-	if (dev->addr_len)
+	if (send_sllao)
 		ndisc_fill_addr_option(opt, ND_OPT_SOURCE_LL_ADDR, dev->dev_addr,
 				       dev->addr_len, dev->type);
 
@@ -798,28 +825,39 @@
 	inc = ipv6_addr_is_multicast(daddr);
 
 	if ((ifp = ipv6_get_ifaddr(&msg->target, dev, 1)) != NULL) {
-		if (ifp->flags & IFA_F_TENTATIVE) {
-			/* Address is tentative. If the source
-			   is unspecified address, it is someone
-			   does DAD, otherwise we ignore solicitations
-			   until DAD timer expires.
-			 */
-			if (!dad)
-				goto out;
-			if (dev->type == ARPHRD_IEEE802_TR) {
-				unsigned char *sadr = skb->mac.raw;
-				if (((sadr[8] ^ dev->dev_addr[0]) & 0x7f) == 0 &&
-				    sadr[9] == dev->dev_addr[1] &&
-				    sadr[10] == dev->dev_addr[2] &&
-				    sadr[11] == dev->dev_addr[3] &&
-				    sadr[12] == dev->dev_addr[4] &&
-				    sadr[13] == dev->dev_addr[5]) {
-					/* looped-back to us */
-					goto out;
+
+		if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) {
+			if (dad) {
+				if (dev->type == ARPHRD_IEEE802_TR) {
+					unsigned char *sadr = skb->mac.raw;
+					if (((sadr[8] ^ dev->dev_addr[0]) & 0x7f) == 0 &&
+					    sadr[9] == dev->dev_addr[1] &&
+					    sadr[10] == dev->dev_addr[2] &&
+					    sadr[11] == dev->dev_addr[3] &&
+					    sadr[12] == dev->dev_addr[4] &&
+					    sadr[13] == dev->dev_addr[5]) {
+						/* looped-back to us */
+						goto out;
+					}
 				}
+
+				/*
+				 * We are colliding with another node
+				 * who is doing DAD
+				 * so fail our DAD process
+				 */
+				addrconf_dad_failure(ifp);
+				goto out;
+			} else {
+				/*
+				 * This is not a dad solicitation.
+				 * If we are an optimistic node,
+				 * we should respond.
+				 * Otherwise, we should ignore it.
+				 */
+				if (!(ifp->flags & IFA_F_OPTIMISTIC))
+					goto out;
 			}
-			addrconf_dad_failure(ifp);
-			return;
 		}
 
 		idev = ifp->idev;
@@ -1408,7 +1446,7 @@
 
 	dev = skb->dev;
 
-	if (ipv6_get_lladdr(dev, &saddr_buf)) {
+	if (ipv6_get_lladdr(dev, &saddr_buf, IFA_F_TENTATIVE)) {
 		ND_PRINTK2(KERN_WARNING
 			   "ICMPv6 Redirect: no link-local address on %s\n",
 			   dev->name);