+ u32 *mtu = ctx;
+ vnet_sw_interface_t *si = vnet_get_sw_interface (vnm, sw_if_index);
+ ASSERT (si);
+
+ si->max_l3_packet_bytes[VLIB_TX] = si->max_l3_packet_bytes[VLIB_RX] = *mtu;
+ adj_mtu_update (sw_if_index);
+}
+
+/*
+ * MTU is set per software interface. Setting MTU on a parent
+ * interface will override the MTU setting on sub-interfaces.
+ * TODO: If sub-interface MTU is ~0 inherit from parent?
+ */
+int
+vnet_sw_interface_set_mtu (vnet_main_t * vnm, u32 sw_if_index, u32 mtu)
+{
+ vnet_sw_interface_t *si = vnet_get_sw_interface (vnm, sw_if_index);
+ vnet_hw_interface_t *hi = vnet_get_sw_hw_interface (vnm, sw_if_index);
+
+ if (mtu < hi->min_packet_bytes)
+ return VNET_API_ERROR_INVALID_VALUE;
+ if (mtu > hi->max_packet_bytes)
+ return VNET_API_ERROR_INVALID_VALUE;