Index: sys/net/route.c
===================================================================
--- sys/net/route.c	(revision 192799)
+++ sys/net/route.c	(working copy)
@@ -1228,41 +1228,41 @@ rtinit1(struct ifaddr *ifa, int cmd, int
 		if (rt_add_addr_allfibs == 0 && cmd == (int)RTM_ADD) {
 			startfib = endfib = curthread->td_proc->p_fibnum;
 		} else {
 			startfib = 0;
 			endfib = rt_numfibs - 1;
 		}
 	} else {
 		KASSERT((fibnum < rt_numfibs), ("rtinit1: bad fibnum"));
 		startfib = fibnum;
 		endfib = fibnum;
 	}
 	if (dst->sa_len == 0)
 		return(EINVAL);
 
 	/*
 	 * If it's a delete, check that if it exists,
 	 * it's on the correct interface or we might scrub
 	 * a route to another ifa which would
 	 * be confusing at best and possibly worse.
 	 */
-	if (cmd == RTM_DELETE) {
+	if (cmd == RTM_DELETE || cmd == RTM_ADD) {
 		/*
 		 * It's a delete, so it should already exist..
 		 * If it's a net, mask off the host bits
 		 * (Assuming we have a mask)
 		 * XXX this is kinda inet specific..
 		 */
 		if (netmask != NULL) {
 			rt_maskedcopy(dst, (struct sockaddr *)tempbuf, netmask);
 			dst = (struct sockaddr *)tempbuf;
 		}
 	}
 	/*
 	 * Now go through all the requested tables (fibs) and do the
 	 * requested action. Realistically, this will either be fib 0
 	 * for protocols that don't do multiple tables or all the
 	 * tables for those that do. XXX For this version only AF_INET.
 	 * When that changes code should be refactored to protocol
 	 * independent parts and protocol dependent parts.
 	 */
 	for ( fibnum = startfib; fibnum <= endfib; fibnum++) {
@@ -1310,40 +1310,52 @@ rtinit1(struct ifaddr *ifa, int cmd, int
 				/* this is only an error if bad on ALL tables */
 				continue;
 			}
 		}
 		/*
 		 * Do the actual request
 		 */
 		bzero((caddr_t)&info, sizeof(info));
 		info.rti_ifa = ifa;
 		info.rti_flags = flags | ifa->ifa_flags;
 		info.rti_info[RTAX_DST] = dst;
 		/* 
 		 * doing this for compatibility reasons
 		 */
 		if (cmd == RTM_ADD)
 			info.rti_info[RTAX_GATEWAY] =
 			    (struct sockaddr *)&null_sdl;
 		else
 			info.rti_info[RTAX_GATEWAY] = ifa->ifa_addr;
 		info.rti_info[RTAX_NETMASK] = netmask;
+		/*
+		 * When adding an interface route - using 'ifconfig up',
+		 * for example - overwrite the route that was already there
+		 * for that subnet.  This fixes a scenario where we take
+		 * an interface down, routing daemon installs new route
+		 * for the subnet formerly reachable through that interface,
+		 * then we bring the interface up, but it remains
+		 * unusable - the routing daemon can't send advertisements
+		 * through it, as there is no route.
+		 */
+		if (cmd == RTM_ADD)
+			rtrequest1_fib(RTM_DELETE, &info, NULL, fibnum);
 		error = rtrequest1_fib(cmd, &info, &rt, fibnum);
 		if (error == 0 && rt != NULL) {
 			/*
 			 * notify any listening routing agents of the change
 			 */
 			RT_LOCK(rt);
 #ifdef RADIX_MPATH
 			/*
 			 * in case address alias finds the first address
 			 * e.g. ifconfig bge0 192.103.54.246/24
 			 * e.g. ifconfig bge0 192.103.54.247/24
 			 * the address set in the route is 192.103.54.246
 			 * so we need to replace it with 192.103.54.247
 			 */
 			if (memcmp(rt->rt_ifa->ifa_addr,
 			    ifa->ifa_addr, ifa->ifa_addr->sa_len)) {
 				IFAFREE(rt->rt_ifa);
 				IFAREF(ifa);
 				rt->rt_ifp = ifa->ifa_ifp;
 				rt->rt_ifa = ifa;