diff --git a/ryu/lib/pack_utils.py b/ryu/lib/pack_utils.py
new file mode 100644
index 00000000..a84d14a7
--- /dev/null
+++ b/ryu/lib/pack_utils.py
@@ -0,0 +1,32 @@
+# Copyright (C) 2011, 2012 Nippon Telegraph and Telephone Corporation.
+# Copyright (C) 2011 Isaku Yamahata <yamahata at valinux co jp>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import struct
+
+
+def msg_pack_into(fmt, buf, offset, *args):
+    if len(buf) < offset:
+        buf += bytearray(offset - len(buf))
+
+    if len(buf) == offset:
+        buf += struct.pack(fmt, *args)
+        return
+
+    needed_len = offset + struct.calcsize(fmt)
+    if len(buf) < needed_len:
+        buf += bytearray(needed_len - len(buf))
+
+    struct.pack_into(fmt, buf, offset, *args)
diff --git a/ryu/lib/packet/bgp.py b/ryu/lib/packet/bgp.py
index 12808c9d..2f507f0c 100644
--- a/ryu/lib/packet/bgp.py
+++ b/ryu/lib/packet/bgp.py
@@ -29,13 +29,13 @@ import copy
 import netaddr
 import numbers
 
-from ryu.ofproto.ofproto_parser import msg_pack_into
 from ryu.lib.stringify import StringifyMixin
 from ryu.lib.packet import afi as addr_family
 from ryu.lib.packet import safi as subaddr_family
 from ryu.lib.packet import packet_base
 from ryu.lib.packet import stream_parser
 from ryu.lib import addrconv
+from ryu.lib.pack_utils import msg_pack_into
 
 BGP_MSG_OPEN = 1
 BGP_MSG_UPDATE = 2
diff --git a/ryu/ofproto/nx_actions.py b/ryu/ofproto/nx_actions.py
index 0bc4a1bd..b097a232 100644
--- a/ryu/ofproto/nx_actions.py
+++ b/ryu/ofproto/nx_actions.py
@@ -20,7 +20,7 @@ from ryu import utils
 from ryu.lib import type_desc
 from ryu.ofproto import nicira_ext
 from ryu.ofproto import ofproto_common
-from ryu.ofproto.ofproto_parser import msg_pack_into
+from ryu.lib.pack_utils import msg_pack_into
 from ryu.ofproto.ofproto_parser import StringifyMixin
 
 
diff --git a/ryu/ofproto/nx_match.py b/ryu/ofproto/nx_match.py
index 5cfeb874..38ce02b5 100644
--- a/ryu/ofproto/nx_match.py
+++ b/ryu/ofproto/nx_match.py
@@ -20,7 +20,7 @@ import itertools
 
 from ryu import exception
 from ryu.lib import mac
-from . import ofproto_parser
+from ryu.lib.pack_utils import msg_pack_into
 from . import ofproto_v1_0
 from . import inet
 
@@ -440,7 +440,7 @@ class MFField(object):
         return cls(header, value, mask)
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset, value)
+        msg_pack_into(self.pack_str, buf, offset, value)
         return self.n_bytes
 
     def putw(self, buf, offset, value, mask):
@@ -459,8 +459,7 @@ class MFField(object):
             return self.putw(buf, offset, value, mask)
 
     def _putv6(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     *value)
+        msg_pack_into(self.pack_str, buf, offset, *value)
         return self.n_bytes
 
     def putv6(self, buf, offset, value, mask):
@@ -1092,7 +1091,7 @@ def serialize_nxm_match(rule, buf, offset):
 
     # Pad
     pad_len = round_up(offset) - offset
-    ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset)
+    msg_pack_into("%dx" % pad_len, buf, offset)
 
     # The returned length, the match_len, does not include the pad
     return offset - old_offset
@@ -1146,6 +1145,6 @@ class NXMatch(object):
                  self.hasmask(), self.length()))
 
     def put_header(self, buf, offset):
-        ofproto_parser.msg_pack_into(ofproto_v1_0.NXM_HEADER_PACK_STRING,
-                                     buf, offset, self.header)
+        msg_pack_into(ofproto_v1_0.NXM_HEADER_PACK_STRING,
+                      buf, offset, self.header)
         return struct.calcsize(ofproto_v1_0.NXM_HEADER_PACK_STRING)
diff --git a/ryu/ofproto/ofproto_parser.py b/ryu/ofproto/ofproto_parser.py
index b883addd..9625cd8b 100644
--- a/ryu/ofproto/ofproto_parser.py
+++ b/ryu/ofproto/ofproto_parser.py
@@ -212,21 +212,6 @@ class MsgInMsgBase(MsgBase):
                                                   **additional_args)
 
 
-def msg_pack_into(fmt, buf, offset, *args):
-    if len(buf) < offset:
-        buf += bytearray(offset - len(buf))
-
-    if len(buf) == offset:
-        buf += struct.pack(fmt, *args)
-        return
-
-    needed_len = offset + struct.calcsize(fmt)
-    if len(buf) < needed_len:
-        buf += bytearray(needed_len - len(buf))
-
-    struct.pack_into(fmt, buf, offset, *args)
-
-
 def namedtuple(typename, fields, **kwargs):
     class _namedtuple(StringifyMixin,
                       collections.namedtuple(typename, fields, **kwargs)):
diff --git a/ryu/ofproto/ofproto_v1_0_parser.py b/ryu/ofproto/ofproto_v1_0_parser.py
index 5d5044ca..477082a3 100644
--- a/ryu/ofproto/ofproto_v1_0_parser.py
+++ b/ryu/ofproto/ofproto_v1_0_parser.py
@@ -21,9 +21,10 @@ Decoder/Encoder implementations of OpenFlow 1.0.
 import struct
 import binascii
 
-from ofproto_parser import StringifyMixin, MsgBase, msg_pack_into, msg_str_attr
+from ofproto_parser import StringifyMixin, MsgBase, msg_str_attr
 from ryu.lib import addrconv
 from ryu.lib import mac
+from ryu.lib.pack_utils import msg_pack_into
 from . import ofproto_common
 from . import ofproto_parser
 from . import ofproto_v1_0 as ofproto
diff --git a/ryu/ofproto/ofproto_v1_2_parser.py b/ryu/ofproto/ofproto_v1_2_parser.py
index 20f3b572..7d00dc42 100644
--- a/ryu/ofproto/ofproto_v1_2_parser.py
+++ b/ryu/ofproto/ofproto_v1_2_parser.py
@@ -23,8 +23,9 @@ import itertools
 
 from ryu.lib import addrconv
 from ryu.lib import mac
+from ryu.lib.pack_utils import msg_pack_into
 from ryu import utils
-from ofproto_parser import StringifyMixin, MsgBase, msg_pack_into, msg_str_attr
+from ofproto_parser import StringifyMixin, MsgBase, msg_str_attr
 from . import ether
 from . import ofproto_parser
 from . import ofproto_v1_2 as ofproto
@@ -1082,7 +1083,7 @@ class OFPInstructionActions(OFPInstruction):
 
         self.len = action_offset - offset
         pad_len = utils.round_up(self.len, 8) - self.len
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, action_offset)
+        msg_pack_into("%dx" % pad_len, buf, action_offset)
         self.len += pad_len
 
         msg_pack_into(ofproto.OFP_INSTRUCTION_ACTIONS_PACK_STR,
@@ -1508,7 +1509,7 @@ class OFPActionSetField(OFPAction):
         self.len = utils.round_up(4 + len_, 8)
         msg_pack_into('!HH', buf, offset, self.type, self.len)
         pad_len = self.len - (4 + len_)
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
+        msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
 
     # XXX old api compat
     def serialize_old(self, buf, offset):
@@ -1519,7 +1520,7 @@ class OFPActionSetField(OFPAction):
         msg_pack_into('!HH', buf, offset, self.type, self.len)
         self.field.serialize(buf, offset + 4)
         offset += len_
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset)
+        msg_pack_into("%dx" % pad_len, buf, offset)
 
     # XXX old api compat
     def _composed_with_old_api(self):
@@ -3561,7 +3562,7 @@ class OFPMatch(StringifyMixin):
         self.length = length
 
         pad_len = utils.round_up(length, 8) - length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, field_offset)
+        msg_pack_into("%dx" % pad_len, buf, field_offset)
 
         return length + pad_len
 
@@ -3766,7 +3767,7 @@ class OFPMatch(StringifyMixin):
         msg_pack_into('!HH', buf, offset, ofproto.OFPMT_OXM, length)
 
         pad_len = utils.round_up(length, 8) - length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, field_offset)
+        msg_pack_into("%dx" % pad_len, buf, field_offset)
 
         return length + pad_len
 
@@ -4073,11 +4074,11 @@ class OFPMatchField(StringifyMixin):
             self.put(buf, offset, self.value)
 
     def _put_header(self, buf, offset):
-        ofproto_parser.msg_pack_into('!I', buf, offset, self.header)
+        msg_pack_into('!I', buf, offset, self.header)
         self.length = 4
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset, value)
+        msg_pack_into(self.pack_str, buf, offset, value)
         self.length += self.n_bytes
 
     def put_w(self, buf, offset, value, mask):
@@ -4090,8 +4091,7 @@ class OFPMatchField(StringifyMixin):
         self._put(buf, offset + self.length, value)
 
     def _putv6(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     *value)
+        msg_pack_into(self.pack_str, buf, offset, *value)
         self.length += self.n_bytes
 
     def putv6(self, buf, offset, value, mask=None):
diff --git a/ryu/ofproto/ofproto_v1_3_parser.py b/ryu/ofproto/ofproto_v1_3_parser.py
index e9b4b293..ea69c8cd 100644
--- a/ryu/ofproto/ofproto_v1_3_parser.py
+++ b/ryu/ofproto/ofproto_v1_3_parser.py
@@ -45,8 +45,9 @@ import itertools
 
 from ryu.lib import addrconv
 from ryu.lib import mac
+from ryu.lib.pack_utils import msg_pack_into
 from ryu import utils
-from ofproto_parser import StringifyMixin, MsgBase, msg_pack_into, msg_str_attr
+from ofproto_parser import StringifyMixin, MsgBase, msg_str_attr
 from . import ether
 from . import nicira_ext
 from . import ofproto_parser
@@ -998,7 +999,7 @@ class OFPMatch(StringifyMixin):
         self.length = length
 
         pad_len = utils.round_up(length, 8) - length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, field_offset)
+        msg_pack_into("%dx" % pad_len, buf, field_offset)
 
         return length + pad_len
 
@@ -1231,7 +1232,7 @@ class OFPMatch(StringifyMixin):
         msg_pack_into('!HH', buf, offset, ofproto.OFPMT_OXM, length)
 
         pad_len = utils.round_up(length, 8) - length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, field_offset)
+        msg_pack_into("%dx" % pad_len, buf, field_offset)
 
         return length + pad_len
 
@@ -1570,11 +1571,11 @@ class OFPMatchField(StringifyMixin):
             self.put(buf, offset, self.value)
 
     def _put_header(self, buf, offset):
-        ofproto_parser.msg_pack_into('!I', buf, offset, self.header)
+        msg_pack_into('!I', buf, offset, self.header)
         self.length = 4
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset, value)
+        msg_pack_into(self.pack_str, buf, offset, value)
         self.length += self.n_bytes
 
     def put_w(self, buf, offset, value, mask):
@@ -1587,8 +1588,7 @@ class OFPMatchField(StringifyMixin):
         self._put(buf, offset + self.length, value)
 
     def _putv6(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     *value)
+        msg_pack_into(self.pack_str, buf, offset, *value)
         self.length += self.n_bytes
 
     def putv6(self, buf, offset, value, mask=None):
@@ -2038,10 +2038,10 @@ class MTPbbIsid(OFPMatchField):
         return cls(header, value, mask)
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     (value >> 16) & 0xff,
-                                     (value >> 8) & 0xff,
-                                     (value >> 0) & 0xff)
+        msg_pack_into(self.pack_str, buf, offset,
+                      (value >> 16) & 0xff,
+                      (value >> 8) & 0xff,
+                      (value >> 0) & 0xff)
         self.length += self.n_bytes
 
 
@@ -2637,7 +2637,7 @@ class OFPInstructionActions(OFPInstruction):
 
         self.len = action_offset - offset
         pad_len = utils.round_up(self.len, 8) - self.len
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, action_offset)
+        msg_pack_into("%dx" % pad_len, buf, action_offset)
         self.len += pad_len
 
         msg_pack_into(ofproto.OFP_INSTRUCTION_ACTIONS_PACK_STR,
@@ -3092,7 +3092,7 @@ class OFPActionSetField(OFPAction):
         self.len = utils.round_up(4 + len_, 8)
         msg_pack_into('!HH', buf, offset, self.type, self.len)
         pad_len = self.len - (4 + len_)
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
+        msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
 
     # XXX old api compat
     def serialize_old(self, buf, offset):
@@ -3103,7 +3103,7 @@ class OFPActionSetField(OFPAction):
         msg_pack_into('!HH', buf, offset, self.type, self.len)
         self.field.serialize(buf, offset + 4)
         offset += len_
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset)
+        msg_pack_into("%dx" % pad_len, buf, offset)
 
     # XXX old api compat
     def _composed_with_old_api(self):
@@ -5295,8 +5295,7 @@ class OFPTableFeaturePropExperimenter(OFPTableFeatureProp):
 
         # data
         if len(self.data):
-            ofproto_parser.msg_pack_into('!%dI' % len(self.data),
-                                         buf, len(buf), *self.data)
+            msg_pack_into('!%dI' % len(self.data), buf, len(buf), *self.data)
 
         return buf
 
diff --git a/ryu/ofproto/ofproto_v1_4_parser.py b/ryu/ofproto/ofproto_v1_4_parser.py
index 1363908d..c4c9054c 100644
--- a/ryu/ofproto/ofproto_v1_4_parser.py
+++ b/ryu/ofproto/ofproto_v1_4_parser.py
@@ -23,9 +23,9 @@ import itertools
 
 from ryu.lib import addrconv
 from ryu.lib import mac
+from ryu.lib.pack_utils import msg_pack_into
 from ryu import utils
-from ofproto_parser import (StringifyMixin, MsgBase, MsgInMsgBase,
-                            msg_pack_into, msg_str_attr)
+from ofproto_parser import StringifyMixin, MsgBase, MsgInMsgBase, msg_str_attr
 from . import ether
 from . import ofproto_parser
 from . import ofproto_common
@@ -769,7 +769,7 @@ class OFPMatch(StringifyMixin):
         self.length = length
 
         pad_len = utils.round_up(length, 8) - length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, field_offset)
+        msg_pack_into("%dx" % pad_len, buf, field_offset)
 
         return length + pad_len
 
@@ -880,7 +880,7 @@ class OFPPropCommonExperimenter4ByteData(StringifyMixin):
 
         # Pad
         pad_len = utils.round_up(self.length, 8) - self.length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, len(buf))
+        msg_pack_into("%dx" % pad_len, buf, len(buf))
 
         return buf
 
@@ -1124,11 +1124,11 @@ class OFPMatchField(StringifyMixin):
             self.put(buf, offset, self.value)
 
     def _put_header(self, buf, offset):
-        ofproto_parser.msg_pack_into('!I', buf, offset, self.header)
+        msg_pack_into('!I', buf, offset, self.header)
         self.length = 4
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset, value)
+        msg_pack_into(self.pack_str, buf, offset, value)
         self.length += self.n_bytes
 
     def put_w(self, buf, offset, value, mask):
@@ -1141,8 +1141,7 @@ class OFPMatchField(StringifyMixin):
         self._put(buf, offset + self.length, value)
 
     def _putv6(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     *value)
+        msg_pack_into(self.pack_str, buf, offset, *value)
         self.length += self.n_bytes
 
     def putv6(self, buf, offset, value, mask=None):
@@ -1596,10 +1595,10 @@ class MTPbbIsid(OFPMatchField):
         return cls(header, value, mask)
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     (value >> 16) & 0xff,
-                                     (value >> 8) & 0xff,
-                                     (value >> 0) & 0xff)
+        msg_pack_into(self.pack_str, buf, offset,
+                      (value >> 16) & 0xff,
+                      (value >> 8) & 0xff,
+                      (value >> 0) & 0xff)
         self.length += self.n_bytes
 
 
@@ -2249,7 +2248,7 @@ class OFPTableFeatureProp(OFPPropBase):
 
         # Pad
         pad_len = utils.round_up(self.length, 8) - self.length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, len(buf))
+        msg_pack_into("%dx" % pad_len, buf, len(buf))
 
         return buf
 
@@ -4943,7 +4942,7 @@ class OFPInstructionActions(OFPInstruction):
 
         self.len = action_offset - offset
         pad_len = utils.round_up(self.len, 8) - self.len
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, action_offset)
+        msg_pack_into("%dx" % pad_len, buf, action_offset)
         self.len += pad_len
 
         msg_pack_into(ofproto.OFP_INSTRUCTION_ACTIONS_PACK_STR,
@@ -5379,7 +5378,7 @@ class OFPActionSetField(OFPAction):
         self.len = utils.round_up(4 + len_, 8)
         msg_pack_into('!HH', buf, offset, self.type, self.len)
         pad_len = self.len - (4 + len_)
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
+        msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
 
     def to_jsondict(self):
         return {
@@ -6068,8 +6067,7 @@ class OFPBundleAddMsg(MsgInMsgBase):
         if len(self.properties) > 0:
             message_len = len(tail_buf)
             pad_len = utils.round_up(message_len, 8) - message_len
-            ofproto_parser.msg_pack_into("%dx" % pad_len, tail_buf,
-                                         message_len)
+            msg_pack_into("%dx" % pad_len, tail_buf, message_len)
 
         # Properties
         for p in self.properties:
diff --git a/ryu/ofproto/ofproto_v1_5_parser.py b/ryu/ofproto/ofproto_v1_5_parser.py
index 4bd9db6b..3c9d9983 100644
--- a/ryu/ofproto/ofproto_v1_5_parser.py
+++ b/ryu/ofproto/ofproto_v1_5_parser.py
@@ -23,9 +23,9 @@ import itertools
 
 from ryu.lib import addrconv
 from ryu.lib import mac
+from ryu.lib.pack_utils import msg_pack_into
 from ryu import utils
-from ofproto_parser import (StringifyMixin, MsgBase, MsgInMsgBase,
-                            msg_pack_into, msg_str_attr)
+from ofproto_parser import StringifyMixin, MsgBase, MsgInMsgBase, msg_str_attr
 from . import ether
 from . import ofproto_parser
 from . import ofproto_common
@@ -769,7 +769,7 @@ class OFPMatch(StringifyMixin):
         self.length = length
 
         pad_len = utils.round_up(length, 8) - length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, field_offset)
+        msg_pack_into("%dx" % pad_len, buf, field_offset)
 
         return length + pad_len
 
@@ -880,7 +880,7 @@ class OFPPropCommonExperimenter4ByteData(StringifyMixin):
 
         # Pad
         pad_len = utils.round_up(self.length, 8) - self.length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, len(buf))
+        msg_pack_into("%dx" % pad_len, buf, len(buf))
 
         return buf
 
@@ -1124,11 +1124,11 @@ class OFPMatchField(StringifyMixin):
             self.put(buf, offset, self.value)
 
     def _put_header(self, buf, offset):
-        ofproto_parser.msg_pack_into('!I', buf, offset, self.header)
+        msg_pack_into('!I', buf, offset, self.header)
         self.length = 4
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset, value)
+        msg_pack_into(self.pack_str, buf, offset, value)
         self.length += self.n_bytes
 
     def put_w(self, buf, offset, value, mask):
@@ -1141,8 +1141,7 @@ class OFPMatchField(StringifyMixin):
         self._put(buf, offset + self.length, value)
 
     def _putv6(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     *value)
+        msg_pack_into(self.pack_str, buf, offset, *value)
         self.length += self.n_bytes
 
     def putv6(self, buf, offset, value, mask=None):
@@ -1596,10 +1595,10 @@ class MTPbbIsid(OFPMatchField):
         return cls(header, value, mask)
 
     def _put(self, buf, offset, value):
-        ofproto_parser.msg_pack_into(self.pack_str, buf, offset,
-                                     (value >> 16) & 0xff,
-                                     (value >> 8) & 0xff,
-                                     (value >> 0) & 0xff)
+        msg_pack_into(self.pack_str, buf, offset,
+                      (value >> 16) & 0xff,
+                      (value >> 8) & 0xff,
+                      (value >> 0) & 0xff)
         self.length += self.n_bytes
 
 
@@ -2249,7 +2248,7 @@ class OFPTableFeatureProp(OFPPropBase):
 
         # Pad
         pad_len = utils.round_up(self.length, 8) - self.length
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, len(buf))
+        msg_pack_into("%dx" % pad_len, buf, len(buf))
 
         return buf
 
@@ -4943,7 +4942,7 @@ class OFPInstructionActions(OFPInstruction):
 
         self.len = action_offset - offset
         pad_len = utils.round_up(self.len, 8) - self.len
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, action_offset)
+        msg_pack_into("%dx" % pad_len, buf, action_offset)
         self.len += pad_len
 
         msg_pack_into(ofproto.OFP_INSTRUCTION_ACTIONS_PACK_STR,
@@ -5348,7 +5347,7 @@ class OFPActionSetField(OFPAction):
         self.len = utils.round_up(4 + len_, 8)
         msg_pack_into('!HH', buf, offset, self.type, self.len)
         pad_len = self.len - (4 + len_)
-        ofproto_parser.msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
+        msg_pack_into("%dx" % pad_len, buf, offset + 4 + len_)
 
     def to_jsondict(self):
         return {
@@ -6067,8 +6066,7 @@ class OFPBundleAddMsg(MsgInMsgBase):
         if len(self.properties) > 0:
             message_len = len(tail_buf)
             pad_len = utils.round_up(message_len, 8) - message_len
-            ofproto_parser.msg_pack_into("%dx" % pad_len, tail_buf,
-                                         message_len)
+            msg_pack_into("%dx" % pad_len, tail_buf, message_len)
 
         # Properties
         for p in self.properties:
diff --git a/ryu/ofproto/oxm_fields.py b/ryu/ofproto/oxm_fields.py
index d8ea8fda..b7936b7d 100644
--- a/ryu/ofproto/oxm_fields.py
+++ b/ryu/ofproto/oxm_fields.py
@@ -63,7 +63,7 @@
 import itertools
 import struct
 import ofproto_common
-from ofproto_parser import msg_pack_into
+from ryu.lib.pack_utils import msg_pack_into
 from ryu.lib import type_desc
 
 
diff --git a/ryu/tests/unit/lib/test_pack_utils.py b/ryu/tests/unit/lib/test_pack_utils.py
new file mode 100644
index 00000000..3bf476f9
--- /dev/null
+++ b/ryu/tests/unit/lib/test_pack_utils.py
@@ -0,0 +1,58 @@
+# Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+import struct
+
+from nose.tools import ok_, eq_
+
+from ryu.lib import pack_utils
+
+
+class TestMsgPackInto(unittest.TestCase):
+    """ Test case for msg_pack_into
+    """
+
+    def _test_msg_pack_into(self, offset_type='e'):
+        fmt = '!HH'
+        len_ = struct.calcsize(fmt)
+        buf = bytearray(len_)
+        offset = len_
+        arg1 = 1
+        arg2 = 2
+
+        if offset_type == 'l':
+            offset += 1
+        elif offset_type == 'g':
+            offset -= 1
+
+        pack_utils.msg_pack_into(fmt, buf, offset, arg1, arg2)
+
+        check_offset = len(buf) - len_
+        res = struct.unpack_from(fmt, buffer(buf), check_offset)
+
+        eq_(arg1, res[0])
+        eq_(arg2, res[1])
+
+        return True
+
+    def test_msg_pack_into(self):
+        ok_(self._test_msg_pack_into())
+
+    def test_msg_pack_into_less(self):
+        ok_(self._test_msg_pack_into('l'))
+
+    def test_msg_pack_into_greater(self):
+        ok_(self._test_msg_pack_into('g'))
diff --git a/ryu/tests/unit/ofproto/test_ofproto_parser.py b/ryu/tests/unit/ofproto/test_ofproto_parser.py
index efc99e9a..e31cf201 100644
--- a/ryu/tests/unit/ofproto/test_ofproto_parser.py
+++ b/ryu/tests/unit/ofproto/test_ofproto_parser.py
@@ -223,43 +223,6 @@ class TestMsgBase(unittest.TestCase):
         ok_(self._test_serialize())
 
 
-class TestMsgPackInto(unittest.TestCase):
-    """ Test case for ofproto_parser.msg_pack_into
-    """
-
-    def _test_msg_pack_into(self, offset_type='e'):
-        fmt = '!HH'
-        len_ = struct.calcsize(fmt)
-        buf = bytearray(len_)
-        offset = len_
-        arg1 = 1
-        arg2 = 2
-
-        if offset_type == 'l':
-            offset += 1
-        elif offset_type == 'g':
-            offset -= 1
-
-        ofproto_parser.msg_pack_into(fmt, buf, offset, arg1, arg2)
-
-        check_offset = len(buf) - len_
-        res = struct.unpack_from(fmt, buffer(buf), check_offset)
-
-        eq_(arg1, res[0])
-        eq_(arg2, res[1])
-
-        return True
-
-    def test_msg_pack_into(self):
-        ok_(self._test_msg_pack_into())
-
-    def test_msg_pack_into_less(self):
-        ok_(self._test_msg_pack_into('l'))
-
-    def test_msg_pack_into_greater(self):
-        ok_(self._test_msg_pack_into('g'))
-
-
 class TestMsgStrAttr(unittest.TestCase):
     """ Test case for ofproto_parser.msg_str_attr
     """
diff --git a/ryu/tests/unit/ofproto/test_parser_v12.py b/ryu/tests/unit/ofproto/test_parser_v12.py
index 13caa526..1ea9b272 100644
--- a/ryu/tests/unit/ofproto/test_parser_v12.py
+++ b/ryu/tests/unit/ofproto/test_parser_v12.py
@@ -29,6 +29,7 @@ from ryu.ofproto import ether
 from ryu.ofproto.ofproto_parser import MsgBase
 from ryu import utils
 from ryu.lib import addrconv
+from ryu.lib import pack_utils
 
 LOG = logging.getLogger('test_ofproto_v12')
 
@@ -6673,12 +6674,11 @@ class TestOFPMatch(unittest.TestCase):
 
     def test_parse_unknown_field(self):
         buf = bytearray()
-        ofproto_parser.msg_pack_into('!HH', buf, 0, ofproto.OFPMT_OXM,
-                                     4 + 6)
+        pack_utils.msg_pack_into('!HH', buf, 0, ofproto.OFPMT_OXM, 4 + 6)
         header = ofproto.oxm_tlv_header(36, 2)
-        ofproto_parser.msg_pack_into('!IH', buf, 4, header, 1)
+        pack_utils.msg_pack_into('!IH', buf, 4, header, 1)
         header = ofproto.OXM_OF_ETH_TYPE
-        ofproto_v1_2_parser.msg_pack_into('!IH', buf, 10, header, 1)
+        pack_utils.msg_pack_into('!IH', buf, 10, header, 1)
 
         match = OFPMatch()
         res = match.parser(str(buf), 0)