diff --git a/sys/net/if_lagg.c b/sys/net/if_lagg.c
--- a/sys/net/if_lagg.c
+++ b/sys/net/if_lagg.c
@@ -137,6 +137,7 @@
 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 *, bool);
 static void	lagg_init(void *);
 static void	lagg_stop(struct lagg_softc *);
 static int	lagg_ioctl(struct ifnet *, u_long, caddr_t);
@@ -1265,6 +1266,25 @@
 	callout_reset(&sc->sc_watchdog, hz, &lagg_watchdog_infiniband, arg);
 }
 
+static void
+lagg_if_updown(struct lagg_softc *sc, bool up)
+{
+	struct ifreq ifr = {};
+	struct lagg_port *lp;
+
+	LAGG_XLOCK_ASSERT(sc);
+
+	CK_SLIST_FOREACH(lp, &sc->sc_ports, lp_entries) {
+		if (up)
+			if_up(lp->lp_ifp);
+		else
+			if_down(lp->lp_ifp);
+
+		if (lp->lp_ioctl != NULL)
+			lp->lp_ioctl(lp->lp_ifp, SIOCSIFFLAGS, (caddr_t)&ifr);
+	}
+}
+
 static void
 lagg_init(void *xsc)
 {
@@ -1291,6 +1311,8 @@
 			if_setlladdr(lp->lp_ifp, IF_LLADDR(ifp), ifp->if_addrlen);
 	}
 
+	lagg_if_updown(sc, true);
+
 	lagg_proto_init(sc);
 
 	if (ifp->if_type == IFT_INFINIBAND) {
@@ -1320,6 +1342,8 @@
 	callout_stop(&sc->sc_watchdog);
 	mtx_unlock(&sc->sc_mtx);
 
+	lagg_if_updown(sc, false);
+
 	callout_drain(&sc->sc_watchdog);
 }
 
diff --git a/tests/sys/net/if_lagg_test.sh b/tests/sys/net/if_lagg_test.sh
--- a/tests/sys/net/if_lagg_test.sh
+++ b/tests/sys/net/if_lagg_test.sh
@@ -358,7 +358,6 @@
 {
 	local TAP0 TAP1 LAGG MAC
 
-	atf_expect_fail "PR 226144 Upping a lagg interrface should automatically up its children"
 	# Configure the lagg interface to use an RFC5737 nonrouteable addresses
 	ADDR="192.0.2.2"
 	MASK="24"