diff --git a/share/man/man4/ng_bridge.4 b/share/man/man4/ng_bridge.4
--- a/share/man/man4/ng_bridge.4
+++ b/share/man/man4/ng_bridge.4
@@ -109,6 +109,22 @@
 Frames with unknown MACs are always sent out to
 .Ar uplink
 hooks, so no functionality is lost.
+.Pp
+Frames with unknown destination MAC addresses are replicated to any
+available hook, unless the first connected hook is an
+.Ar uplink
+hook.
+In this case the node assumes, that all unknown MAC addresses are
+located soley on the
+.Ar uplink
+hooks and only those hooks will be used to send out frames with
+unknown destination MACs.
+If the first connected hook is an
+.Ar link
+hook, the node will replicate such frames to all types of hooks,
+even if
+.Ar uplink
+hooks are connected later.
 .Sh CONTROL MESSAGES
 This node type supports the generic control messages, plus the
 following:
diff --git a/sys/netgraph/ng_bridge.c b/sys/netgraph/ng_bridge.c
--- a/sys/netgraph/ng_bridge.c
+++ b/sys/netgraph/ng_bridge.c
@@ -105,7 +105,8 @@
 	u_int			numBuckets;	/* num buckets in table */
 	u_int			hashMask;	/* numBuckets - 1 */
 	int			numLinks;	/* num connected links */
-	int			persistent;	/* can exist w/o hooks */
+	unsigned int		persistent : 1,	/* can exist w/o hooks */
+				sendUnknown : 1;/* links receive unknowns by default */
 	struct callout		timer;		/* one second periodic timer */
 };
 typedef struct ng_bridge_private *priv_p;
@@ -309,6 +310,7 @@
 	priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
 	priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
 	priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
+	priv->sendUnknown = 1;	       /* classic bridge */
 
 	/*
 	 * This node has all kinds of stuff that could be screwed by SMP.
@@ -371,9 +373,11 @@
 	if (isUplink) {
 		link->learnMac = 0;
 		link->sendUnknown = 1;
+		if (priv->numLinks == 0)	/* if the first link is an uplink */
+		    priv->sendUnknown = 0;	/* switch to restrictive mode */
 	} else {
 		link->learnMac = 1;
-		link->sendUnknown = 1;
+		link->sendUnknown = priv->sendUnknown;
 	}
 
 	NG_HOOK_SET_PRIVATE(hook, link);