diff --git a/rdpy/protocol/common/error.py b/rdpy/protocol/common/error.py
new file mode 100644
index 0000000..04f7072
--- /dev/null
+++ b/rdpy/protocol/common/error.py
@@ -0,0 +1,20 @@
+'''
+@author: sylvain
+'''
+
+class InvalidExpectedDataException(Exception):
+    '''
+    raise when expected data on network is invalid
+    '''
+    def __init__(self, message):
+        '''
+        constructor with message
+        '''
+        self._message = message
+        
+    def __str__(self):
+        '''
+        return string representation of exception
+        '''
+        return "%s"%self._message
+        
diff --git a/rdpy/protocol/rdp/tpdu.py b/rdpy/protocol/rdp/tpdu.py
index f7a99b1..cee2fad 100644
--- a/rdpy/protocol/rdp/tpdu.py
+++ b/rdpy/protocol/rdp/tpdu.py
@@ -5,6 +5,7 @@ Created on 5 sept. 2013
 '''
 from rdpy.protocol.common.layer import Layer
 from rdpy.protocol.common.stream import Stream
+from rdpy.protocol.common.error import InvalidExpectedDataException
 class TPDU(Layer):
     '''
     classdocs
@@ -23,8 +24,35 @@ class TPDU(Layer):
     
     def connect(self):
         self.writeMessage(TPDU.X224_TPDU_CONNECTION_REQUEST)
+        
+    def recv(self, data):
+        '''
+        main receive function
+        layer complexity doesn't need automata
+        '''
+        #unused length
+        len = data.read_uint8()
+        code = data.read_uint8()
+        
+        if code == TPDU.X224_TPDU_DATA:
+            data.read_uint8()
+            self._presentation.recv(data)
+        else:
+            #padding
+            data.read_leuint32()
+            if code == TPDU.X224_TPDU_CONNECTION_CONFIRM:
+                self._presentation.connect()
+            elif code == TPDU.X224_TPDU_CONNECTION_REQUEST:
+                self.writeMessage(TPDU.X224_TPDU_CONNECTION_CONFIRM)
+                self._presentation.connect()
+            else:
+                raise InvalidExpectedDataException("invalid TPDU header code %d"%code) 
     
     def write(self, data):
+        '''
+        write message packet for TPDU layer
+        add TPDU header
+        '''
         s = Stream()
         s.write_uint8(2)
         s.write_uint8(TPDU.X224_TPDU_DATA)
@@ -33,10 +61,14 @@ class TPDU(Layer):
         self._transport.write(data)
         
     def writeMessage(self, code):
+        '''
+        special write function
+        that packet TPDU message
+        '''
         s = Stream()
-        s.write_uint8(6);
-        s.write_uint8(code);
-        s.write_beuint16(0);
-        s.write_beuint16(0);
-        s.write_uint8(0);
+        s.write_uint8(6)
+        s.write_uint8(code)
+        s.write_beuint16(0)
+        s.write_beuint16(0)
+        s.write_uint8(0)
         self.write(s)
\ No newline at end of file
diff --git a/rdpy/protocol/rdp/tpkt.py b/rdpy/protocol/rdp/tpkt.py
index 9b8bc90..16d4f57 100644
--- a/rdpy/protocol/rdp/tpkt.py
+++ b/rdpy/protocol/rdp/tpkt.py
@@ -78,7 +78,7 @@ class TPKT(RawLayer):
         read classic TPKT packet
         '''
         #next state is pass to 
-        self.recv(data)
+        self._presentation.recv(data)
         self.expect(2, self.readHeader)
         
     def write(self, data):