diff --git a/demos/host/src/cdc_serial_app.c b/demos/host/src/cdc_serial_app.c
index cb07b0501..16a130c85 100644
--- a/demos/host/src/cdc_serial_app.c
+++ b/demos/host/src/cdc_serial_app.c
@@ -61,6 +61,9 @@ static uint8_t buffer_in[64] TUSB_CFG_ATTR_USBRAM;
 void tusbh_cdc_mounted_cb(uint8_t dev_addr)
 {
   // application set-up
+
+  printf("a CDC device is mounted\n");
+
   osal_queue_flush(queue_hdl);
   tusbh_cdc_receive(dev_addr, buffer_in, sizeof(buffer_in), true); // first report
 }
diff --git a/demos/host/src/keyboard_app.c b/demos/host/src/keyboard_app.c
index c80ad6bc2..4e027a163 100644
--- a/demos/host/src/keyboard_app.c
+++ b/demos/host/src/keyboard_app.c
@@ -70,6 +70,9 @@ static inline void process_kbd_report(tusb_keyboard_report_t const * report);
 void tusbh_hid_keyboard_mounted_cb(uint8_t dev_addr)
 {
   // application set-up
+
+  printf("a keyboard device is mounted\n");
+
   osal_queue_flush(queue_kbd_hdl);
   tusbh_hid_keyboard_get_report(dev_addr, (uint8_t*) &usb_keyboard_report); // first report
 }
diff --git a/demos/host/src/mouse_app.c b/demos/host/src/mouse_app.c
index b7eba887f..6845dacbb 100644
--- a/demos/host/src/mouse_app.c
+++ b/demos/host/src/mouse_app.c
@@ -70,6 +70,9 @@ static inline void process_mouse_report(tusb_mouse_report_t const * p_report);
 void tusbh_hid_mouse_mounted_cb(uint8_t dev_addr)
 {
   // application set-up
+
+  printf("a mouse device is mounted\n");
+
   osal_queue_flush(queue_mouse_hdl);
   tusbh_hid_mouse_get_report(dev_addr, (uint8_t*) &usb_mouse_report); // first report
 }
diff --git a/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.c b/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.c
index 16af1db27..d6b36c92b 100644
--- a/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.c
+++ b/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.c
@@ -39,6 +39,9 @@
 #include "tusb_option.h"
 #include "descriptor_cdc.h"
 
+//--------------------------------------------------------------------+
+// CDC Serials
+//--------------------------------------------------------------------+
 TUSB_CFG_ATTR_USBRAM
 const cdc_configuration_desc_t cdc_config_descriptor =
 {
@@ -160,3 +163,126 @@ const cdc_configuration_desc_t cdc_config_descriptor =
         .bInterval        = 0
     },
 };
+
+//--------------------------------------------------------------------+
+// CDC RNSID
+//--------------------------------------------------------------------+
+
+TUSB_CFG_ATTR_USBRAM
+const cdc_configuration_desc_t rndis_config_descriptor =
+{
+    .configuration =
+    {
+        .bLength             = sizeof(tusb_descriptor_configuration_t),
+        .bDescriptorType     = TUSB_DESC_TYPE_CONFIGURATION,
+
+        .wTotalLength        = sizeof(cdc_configuration_desc_t),
+        .bNumInterfaces      = 2,
+
+        .bConfigurationValue = 1,
+        .iConfiguration      = 0x00,
+        .bmAttributes        = TUSB_DESC_CONFIG_ATT_BUS_POWER,
+        .bMaxPower           = TUSB_DESC_CONFIG_POWER_MA(100)
+    },
+
+    // IAD points to CDC Interfaces
+    .cdc_iad =
+    {
+        .bLength           = sizeof(tusb_descriptor_interface_association_t),
+        .bDescriptorType   = TUSB_DESC_TYPE_INTERFACE_ASSOCIATION,
+
+        .bFirstInterface   = 1,
+        .bInterfaceCount   = 2,
+
+        .bFunctionClass    = TUSB_CLASS_CDC,
+        .bFunctionSubClass = CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL,
+        .bFunctionProtocol = 0,
+
+        .iFunction         = 0
+    },
+
+
+    // USB CDC Serial Interface
+    //------------- CDC Communication Interface -------------//
+    .cdc_comm_interface =
+    {
+        .bLength            = sizeof(tusb_descriptor_interface_t),
+        .bDescriptorType    = TUSB_DESC_TYPE_INTERFACE,
+        .bInterfaceNumber   = 1,
+        .bAlternateSetting  = 0,
+        .bNumEndpoints      = 1,
+        .bInterfaceClass    = TUSB_CLASS_CDC,
+        .bInterfaceSubClass = CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL,
+        .bInterfaceProtocol = 0xff, // RNDIS is vendor specific protocol
+        .iInterface         = 0x00
+    },
+
+    .cdc_header =
+    {
+        .bLength            = sizeof(cdc_desc_func_header_t),
+        .bDescriptorType    = TUSB_DESC_TYPE_INTERFACE_CLASS_SPECIFIC,
+        .bDescriptorSubType = CDC_FUNC_DESC_HEADER,
+        .bcdCDC             = 0x0120
+    },
+
+    .cdc_acm =
+    {
+        .bLength            = sizeof(cdc_desc_func_abstract_control_management_t),
+        .bDescriptorType    = TUSB_DESC_TYPE_INTERFACE_CLASS_SPECIFIC,
+        .bDescriptorSubType = CDC_FUNC_DESC_ABSTRACT_CONTROL_MANAGEMENT,
+        .bmCapabilities     = { 0 }
+    },
+
+    .cdc_union =
+    {
+        .bLength                  = sizeof(cdc_desc_func_union_t), // plus number of
+        .bDescriptorType          = TUSB_DESC_TYPE_INTERFACE_CLASS_SPECIFIC,
+        .bDescriptorSubType       = CDC_FUNC_DESC_UNION,
+        .bControlInterface        = 1,
+        .bSubordinateInterface    = 2,
+    },
+
+    .cdc_endpoint_notification =
+    {
+        .bLength          = sizeof(tusb_descriptor_endpoint_t),
+        .bDescriptorType  = TUSB_DESC_TYPE_ENDPOINT,
+        .bEndpointAddress = 0x81,
+        .bmAttributes     = { .xfer = TUSB_XFER_INTERRUPT },
+        .wMaxPacketSize   = 8,
+        .bInterval        = 0x0a // lowest polling rate
+    },
+
+    //------------- CDC Data Interface -------------//
+    .cdc_data_interface =
+    {
+        .bLength            = sizeof(tusb_descriptor_interface_t),
+        .bDescriptorType    = TUSB_DESC_TYPE_INTERFACE,
+        .bInterfaceNumber   = 2,
+        .bAlternateSetting  = 0x00,
+        .bNumEndpoints      = 2,
+        .bInterfaceClass    = TUSB_CLASS_CDC_DATA,
+        .bInterfaceSubClass = 0,
+        .bInterfaceProtocol = 0,
+        .iInterface         = 0x00
+    },
+
+    .cdc_endpoint_out =
+    {
+        .bLength          = sizeof(tusb_descriptor_endpoint_t),
+        .bDescriptorType  = TUSB_DESC_TYPE_ENDPOINT,
+        .bEndpointAddress = 2,
+        .bmAttributes     = { .xfer = TUSB_XFER_BULK },
+        .wMaxPacketSize   = 512,
+        .bInterval        = 0
+    },
+
+    .cdc_endpoint_in =
+    {
+        .bLength          = sizeof(tusb_descriptor_endpoint_t),
+        .bDescriptorType  = TUSB_DESC_TYPE_ENDPOINT,
+        .bEndpointAddress = 0x82,
+        .bmAttributes     = { .xfer = TUSB_XFER_BULK },
+        .wMaxPacketSize   = 512,
+        .bInterval        = 0
+    },
+};
diff --git a/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.h b/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.h
index 618896e1d..2b7774fb2 100644
--- a/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.h
+++ b/tests/lpc18xx_43xx/test/host/cdc/descriptor_cdc.h
@@ -74,6 +74,7 @@ typedef struct
 } cdc_configuration_desc_t;
 
 extern const cdc_configuration_desc_t cdc_config_descriptor;
+extern const cdc_configuration_desc_t rndis_config_descriptor;
 
 #ifdef __cplusplus
  }
diff --git a/tests/lpc18xx_43xx/test/host/cdc/test_cdc_host.c b/tests/lpc18xx_43xx/test/host/cdc/test_cdc_host.c
index e803137d4..51d3d2ce2 100644
--- a/tests/lpc18xx_43xx/test/host/cdc/test_cdc_host.c
+++ b/tests/lpc18xx_43xx/test/host/cdc/test_cdc_host.c
@@ -51,16 +51,16 @@
 #include "descriptor_cdc.h"
 #include "cdc_host.h"
 
-uint8_t dev_addr;
-uint16_t length;
+static uint8_t dev_addr;
+static uint16_t length;
 
-tusb_descriptor_interface_t const * p_comm_interface = &cdc_config_descriptor.cdc_comm_interface;
-tusb_descriptor_endpoint_t const * p_endpoint_notification = &cdc_config_descriptor.cdc_endpoint_notification;
-tusb_descriptor_endpoint_t const * p_endpoint_out = &cdc_config_descriptor.cdc_endpoint_out;
-tusb_descriptor_endpoint_t const * p_endpoint_in = &cdc_config_descriptor.cdc_endpoint_in;
+static tusb_descriptor_interface_t const * p_comm_interface = &cdc_config_descriptor.cdc_comm_interface;
+static tusb_descriptor_endpoint_t const * p_endpoint_notification = &cdc_config_descriptor.cdc_endpoint_notification;
+static tusb_descriptor_endpoint_t const * p_endpoint_out = &cdc_config_descriptor.cdc_endpoint_out;
+static tusb_descriptor_endpoint_t const * p_endpoint_in = &cdc_config_descriptor.cdc_endpoint_in;
 
 extern cdch_data_t cdch_data[TUSB_CFG_HOST_DEVICE_MAX];
-cdch_data_t * p_cdc = &cdch_data[0];
+static cdch_data_t * p_cdc = &cdch_data[0];
 
 void setUp(void)
 {
@@ -149,6 +149,19 @@ void test_cdch_open_interface_number_check(void)
 
 }
 
+void test_cdch_open_protocol_check(void)
+{
+  pipe_handle_t dummy_hld = { .dev_addr = 1 };
+  hcd_pipe_open_IgnoreAndReturn(dummy_hld);
+  tusbh_cdc_mounted_cb_Expect(dev_addr);
+
+  //------------- CUT -------------//
+  TEST_ASSERT_EQUAL( TUSB_ERROR_NONE, cdch_open_subtask(dev_addr, p_comm_interface, &length) );
+
+  TEST_ASSERT_EQUAL(p_comm_interface->bInterfaceProtocol, p_cdc->interface_protocol);
+
+}
+
 void test_cdch_open_acm_capacity_check(void)
 {
   pipe_handle_t dummy_hld = { .dev_addr = 1 };
diff --git a/tests/lpc18xx_43xx/test/host/cdc/test_cdc_rndis_host.c b/tests/lpc18xx_43xx/test/host/cdc/test_cdc_rndis_host.c
new file mode 100644
index 000000000..0e661073a
--- /dev/null
+++ b/tests/lpc18xx_43xx/test/host/cdc/test_cdc_rndis_host.c
@@ -0,0 +1,93 @@
+/**************************************************************************/
+/*!
+    @file     test_cdc_rndis_host.c
+    @author   hathach (tinyusb.org)
+
+    @section LICENSE
+
+    Software License Agreement (BSD License)
+
+    Copyright (c) 2013, hathach (tinyusb.org)
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are met:
+    1. Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+    3. Neither the name of the copyright holders nor the
+    names of its contributors may be used to endorse or promote products
+    derived from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
+    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
+    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+    This file is part of the tinyusb stack.
+*/
+/**************************************************************************/
+
+#include "stdlib.h"
+#include "unity.h"
+#include "tusb_option.h"
+#include "errors.h"
+#include "binary.h"
+#include "type_helper.h"
+
+#include "mock_osal.h"
+#include "mock_hcd.h"
+#include "mock_usbh.h"
+#include "mock_cdc_callback.h"
+
+#include "descriptor_cdc.h"
+#include "cdc_host.h"
+
+static uint8_t dev_addr;
+static uint16_t length;
+
+static tusb_descriptor_interface_t const * p_comm_interface = &rndis_config_descriptor.cdc_comm_interface;
+static tusb_descriptor_endpoint_t const * p_endpoint_notification = &rndis_config_descriptor.cdc_endpoint_notification;
+static tusb_descriptor_endpoint_t const * p_endpoint_out = &rndis_config_descriptor.cdc_endpoint_out;
+static tusb_descriptor_endpoint_t const * p_endpoint_in = &rndis_config_descriptor.cdc_endpoint_in;
+
+static pipe_handle_t pipe_notification = { .dev_addr = 1, .xfer_type = TUSB_XFER_INTERRUPT };
+static pipe_handle_t pipe_out          = { .dev_addr  = 1, .xfer_type = TUSB_XFER_BULK, .index = 0 };
+static pipe_handle_t pipe_int          = { .dev_addr  = 1, .xfer_type = TUSB_XFER_BULK, .index = 1 };
+
+extern cdch_data_t cdch_data[TUSB_CFG_HOST_DEVICE_MAX];
+static cdch_data_t * p_cdc = &cdch_data[0];
+
+
+void setUp(void)
+{
+  length = 0;
+  dev_addr = 1;
+
+  cdch_init();
+
+  hcd_pipe_open_ExpectAndReturn(dev_addr, p_endpoint_notification, TUSB_CLASS_CDC, pipe_notification);
+  hcd_pipe_open_ExpectAndReturn(dev_addr, p_endpoint_out, TUSB_CLASS_CDC, pipe_out);
+  hcd_pipe_open_ExpectAndReturn(dev_addr, p_endpoint_in, TUSB_CLASS_CDC, pipe_int);
+  tusbh_cdc_mounted_cb_Expect(dev_addr);
+
+  TEST_ASSERT_EQUAL( TUSB_ERROR_NONE, cdch_open_subtask(dev_addr, p_comm_interface, &length) );
+}
+
+void tearDown(void)
+{
+
+}
+
+void test_(void)
+{
+
+}
diff --git a/tinyusb/class/cdc_host.c b/tinyusb/class/cdc_host.c
index 3831fc243..ac4338853 100644
--- a/tinyusb/class/cdc_host.c
+++ b/tinyusb/class/cdc_host.c
@@ -134,7 +134,8 @@ tusb_error_t cdch_open_subtask(uint8_t dev_addr, tusb_descriptor_interface_t con
     return TUSB_ERROR_CDCH_UNSUPPORTED_SUBCLASS;
   }
 
-  if (CDC_COMM_PROTOCOL_ATCOMMAND != p_interface_desc->bInterfaceProtocol)
+  if ( !(is_in_range(CDC_COMM_PROTOCOL_ATCOMMAND, p_interface_desc->bInterfaceProtocol, CDC_COMM_PROTOCOL_ATCOMMAND_CDMA) ||
+         0xff == p_interface_desc->bInterfaceProtocol) )
   {
     return TUSB_ERROR_CDCH_UNSUPPORTED_PROTOCOL;
   }
diff --git a/tinyusb/common/common.h b/tinyusb/common/common.h
index ed543de00..3a43f123c 100644
--- a/tinyusb/common/common.h
+++ b/tinyusb/common/common.h
@@ -192,6 +192,21 @@ static inline uint32_t offset4k(uint32_t value)
 }
 
 //------------- Mathematics -------------//
+/// inclusive range checking
+static inline bool is_in_range(uint32_t lower, uint32_t value, uint32_t upper) ATTR_ALWAYS_INLINE ATTR_CONST;
+static inline bool is_in_range(uint32_t lower, uint32_t value, uint32_t upper)
+{
+  return (lower <= value) && (value <= upper);
+}
+
+/// exclusive range checking
+static inline bool is_in_range_exclusive(uint32_t lower, uint32_t value, uint32_t upper) ATTR_ALWAYS_INLINE ATTR_CONST;
+static inline bool is_in_range_exclusive(uint32_t lower, uint32_t value, uint32_t upper)
+{
+  return (lower < value) && (value < upper);
+}
+
+
 static inline uint8_t log2_of(uint32_t value) ATTR_ALWAYS_INLINE ATTR_CONST;
 static inline uint8_t log2_of(uint32_t value)
 {