Index: head/sys/net/ifdi_if.m
===================================================================
--- head/sys/net/ifdi_if.m
+++ head/sys/net/ifdi_if.m
@@ -169,6 +169,12 @@
 	    }
 	    return (0);
 	}
+
+	static bool
+	null_needs_restart(if_ctx_t _ctx __unused, enum iflib_restart_event _event __unused)
+	{
+		return (true);
+	}
 };
 
 #
@@ -456,3 +462,8 @@
 METHOD void debug {
 	if_ctx_t _ctx;
 } DEFAULT null_void_op;
+
+METHOD bool needs_restart {
+	if_ctx_t _ctx;
+	enum iflib_restart_event _event;
+} DEFAULT null_needs_restart;
Index: head/sys/net/iflib.h
===================================================================
--- head/sys/net/iflib.h
+++ head/sys/net/iflib.h
@@ -377,6 +377,15 @@
 #define	IFLIB_SINGLE_IRQ_RX_ONLY	0x40000
 
 /*
+ * These enum values are used in iflib_needs_restart to indicate to iflib
+ * functions whether or not the interface needs restarting when certain events
+ * happen.
+ */
+enum iflib_restart_event {
+	IFLIB_RESTART_VLAN_CONFIG,
+};
+
+/*
  * field accessors
  */
 void *iflib_get_softc(if_ctx_t ctx);
Index: head/sys/net/iflib.c
===================================================================
--- head/sys/net/iflib.c
+++ head/sys/net/iflib.c
@@ -4308,10 +4308,13 @@
 		return;
 
 	CTX_LOCK(ctx);
+	/* Driver may need all untagged packets to be flushed */
+	if (IFDI_NEEDS_RESTART(ctx, IFLIB_RESTART_VLAN_CONFIG))
+		iflib_stop(ctx);
 	IFDI_VLAN_REGISTER(ctx, vtag);
-	/* Re-init to load the changes */
-	if (if_getcapenable(ifp) & IFCAP_VLAN_HWFILTER)
-		iflib_if_init_locked(ctx);
+	/* Re-init to load the changes, if required */
+	if (IFDI_NEEDS_RESTART(ctx, IFLIB_RESTART_VLAN_CONFIG))
+		iflib_init_locked(ctx);
 	CTX_UNLOCK(ctx);
 }
 
@@ -4327,10 +4330,13 @@
 		return;
 
 	CTX_LOCK(ctx);
+	/* Driver may need all tagged packets to be flushed */
+	if (IFDI_NEEDS_RESTART(ctx, IFLIB_RESTART_VLAN_CONFIG))
+		iflib_stop(ctx);
 	IFDI_VLAN_UNREGISTER(ctx, vtag);
-	/* Re-init to load the changes */
-	if (if_getcapenable(ifp) & IFCAP_VLAN_HWFILTER)
-		iflib_if_init_locked(ctx);
+	/* Re-init to load the changes, if required */
+	if (IFDI_NEEDS_RESTART(ctx, IFLIB_RESTART_VLAN_CONFIG))
+		iflib_init_locked(ctx);
 	CTX_UNLOCK(ctx);
 }