Index: sys/dev/usb/net/if_smsc.c
===================================================================
--- sys/dev/usb/net/if_smsc.c	(revision 290536)
+++ sys/dev/usb/net/if_smsc.c	(working copy)
@@ -1707,7 +1707,7 @@
 	/* The chip supports TCP/UDP checksum offloading on TX and RX paths, however
 	 * currently only RX checksum is supported in the driver (see top of file).
 	 */
-	ifp->if_capabilities |= IFCAP_RXCSUM;
+	ifp->if_capabilities |= IFCAP_RXCSUM | IFCAP_VLAN_MTU;
 	ifp->if_hwassist = 0;
 	
 	/* TX checksuming is disabled (for now?)