--- //SpectraBSD/stable/sys/net/if_lagg.c	2013-02-18 03:17:28.000000000 -0700
+++ //SpectraBSD/stable/sys/net/if_lagg.c	2013-03-28 21:27:00.000000000 -0600
@@ -102,6 +102,7 @@
 static int	lagg_port_checkstacking(struct lagg_softc *);
 #endif
 static void	lagg_port2req(struct lagg_port *, struct lagg_reqport *);
+static void	lagg_if_updown(struct lagg_softc *, int);
 static void	lagg_init(void *);
 static void	lagg_stop(struct lagg_softc *);
 static int	lagg_ioctl(struct ifnet *, u_long, caddr_t);
@@ -589,6 +590,7 @@
 	/* Insert into the list of ports */
 	SLIST_INSERT_HEAD(&sc->sc_ports, lp, lp_entries);
 	sc->sc_count++;
+	sc->sc_generation++;
 
 	/* Update lagg capabilities */
 	lagg_capabilities(sc);
@@ -662,6 +664,7 @@
 	/* Finally, remove the port from the lagg */
 	SLIST_REMOVE(&sc->sc_ports, lp, lagg_port, lp_entries);
 	sc->sc_count--;
+	sc->sc_generation++;
 
 	/* Update the primary interface */
 	if (lp == sc->sc_primary) {
@@ -753,7 +756,11 @@
 		break;
 
 	case SIOCSIFMTU:
-		/* Do not allow the MTU to be changed once joined */
+		/*
+		 * We don't allow changing the MTU on a per-port basis once
+		 * the port is part of a lagg.  The user must change the
+		 * MTU of the lagg as a whole.
+		 */
 		error = EINVAL;
 		break;
 
@@ -852,6 +859,40 @@
 }
 
 static void
+lagg_if_updown(struct lagg_softc *sc, int up)
+{
+	struct lagg_port *lp;
+
+	LAGG_WLOCK_ASSERT(sc);
+
+startover:
+
+	SLIST_FOREACH(lp, &sc->sc_ports, lp_entries) {
+		struct ifreq ifr;
+		uint64_t cur_generation;
+		int error;
+
+		if (up != 0)
+			if_up(lp->lp_ifp);
+		else
+			if_down(lp->lp_ifp);
+
+		if (lp->lp_ioctl == NULL)
+			continue;
+		bzero(&ifr, sizeof(ifr));
+
+		cur_generation = sc->sc_generation;
+
+		LAGG_WUNLOCK(sc);
+		error = lp->lp_ioctl(lp->lp_ifp, SIOCSIFFLAGS, (caddr_t)&ifr);
+		LAGG_WLOCK(sc);
+
+		if (cur_generation != sc->sc_generation)
+			goto startover;
+	}
+}
+
+static void
 lagg_init(void *xsc)
 {
 	struct lagg_softc *sc = (struct lagg_softc *)xsc;
@@ -868,6 +909,8 @@
 	SLIST_FOREACH(lp, &sc->sc_ports, lp_entries)
 		lagg_port_lladdr(lp, IF_LLADDR(ifp));
 
+	lagg_if_updown(sc, /*up*/ 1);
+
 	if (sc->sc_init != NULL)
 		(*sc->sc_init)(sc);
 
@@ -888,6 +931,8 @@
 
 	if (sc->sc_stop != NULL)
 		(*sc->sc_stop)(sc);
+
+	lagg_if_updown(sc, /*up*/ 0);
 }
 
 static int
@@ -1096,11 +1141,78 @@
 		break;
 
 	case SIOCSIFCAP:
-	case SIOCSIFMTU:
-		/* Do not allow the MTU or caps to be directly changed */
+		/* Do not allow caps to be directly changed */
 		error = EINVAL;
 		break;
+	case SIOCSIFMTU: {
+		struct ifreq *ifr;
+		int new_mtu, old_mtu;
+		int error2 = 0;
+
+		ifr = (struct ifreq *)data;
+
+		new_mtu = ifr->ifr_mtu;
+
+		old_mtu = sc->sc_ifp->if_mtu;
+		/* Nothing to do if there is no change */
+		if (new_mtu == old_mtu)
+			break;
 
+		LAGG_WLOCK(sc);
+		SLIST_FOREACH(lp, &sc->sc_ports, lp_entries) {
+			if (lp->lp_ioctl == NULL) {
+				printf("%s: SIOCSIFMTU: unable to change "
+				    "MTU for %s because it has no ioctl "
+				    "routine\n", __func__,
+				    lp->lp_ifp->if_xname);
+				error = EINVAL;
+				break;
+			}
+			error = lp->lp_ioctl(lp->lp_ifp, cmd, data);
+			/*
+			 * If we get an error setting the MTU for this
+			 * component interface, just exit, and below we'll
+			 * try to reset all of the ports to the previous
+			 * value.
+			 */
+			if (error != 0) {
+				printf("%s: SIOCSIFMTU: error %d changing MTU "
+				    "for %s from %d to %d\n", __func__, error,
+				    lp->lp_ifp->if_xname, old_mtu, new_mtu);
+				break;
+			}
+		}
+		if (error == 0) {
+			/* We were successful, so update our saved MTU. */
+			sc->sc_ifp->if_mtu = new_mtu;
+			LAGG_WUNLOCK(sc);
+			break;
+		}
+		/*
+		 * In the error case, try to reset all of the ports to
+		 * their previous value.
+		 */
+		SLIST_FOREACH(lp, &sc->sc_ports, lp_entries) {
+			if (lp->lp_ioctl == NULL)
+				continue;
+
+			error2 = lp->lp_ioctl(lp->lp_ifp, cmd,
+			    (caddr_t)&old_mtu);
+			/*
+			 * This shouldn't fail, because the port was
+			 * previously at this MTU.  If it does for some
+			 * reason, continue on to get as many ports as
+			 * possible back to the old MTU.
+			 */
+			if (error2 != 0) {
+				printf("%s: SIOCSIFMTU: error %d changing MTU "
+				    "for %s back to %d\n", __func__, error,
+				    lp->lp_ifp->if_xname, old_mtu);
+			}
+		}
+		LAGG_WUNLOCK(sc);
+		break;
+	}
 	default:
 		error = ether_ioctl(ifp, cmd, data);
 		break;
--- //SpectraBSD/stable/sys/net/if_lagg.h	2012-08-29 22:35:04.000000000 -0600
+++ //SpectraBSD/stable/sys/net/if_lagg.h	2013-03-28 21:27:00.000000000 -0600
@@ -189,6 +189,7 @@
 	struct rwlock			sc_mtx;
 	int				sc_proto;	/* lagg protocol */
 	u_int				sc_count;	/* number of ports */
+	uint64_t			sc_generation;	/* generation count */
 	struct lagg_port		*sc_primary;	/* primary port */
 	struct ifmedia			sc_media;	/* media config */
 	caddr_t				sc_psc;		/* protocol data */