diff --git a/yabgp/config.py b/yabgp/config.py
index 8addda7..590bf4e 100644
--- a/yabgp/config.py
+++ b/yabgp/config.py
@@ -91,11 +91,11 @@
                help='The remote BGP peer AS number'),
     cfg.IntOpt('local_as',
                help='The Local BGP AS number'),
-    cfg.StrOpt('remote_addr',
-               help='The remote address of the peer'),
-    cfg.StrOpt('local_addr',
-               default='0.0.0.0',
-               help='The local address of the BGP'),
+    cfg.IPOpt('remote_addr',
+              help='The remote address of the peer'),
+    cfg.IPOpt('local_addr',
+              default='0.0.0.0',
+              help='The local address of the BGP'),
     cfg.StrOpt('md5',
                help='The MD5 string use to auth',
                secret=True),
diff --git a/yabgp/message/attribute/mpreachnlri.py b/yabgp/message/attribute/mpreachnlri.py
index 865408f..d829833 100644
--- a/yabgp/message/attribute/mpreachnlri.py
+++ b/yabgp/message/attribute/mpreachnlri.py
@@ -118,7 +118,7 @@ def parse(cls, value):
         else:
             nlri = repr(nlri_bin)
 
-        return dict(afi_safi=(afi, safi), nexthop=nexthop_bin, nlri=nlri)
+        return dict(afi_safi=(afi, safi), nexthop=nexthop_bin, nlri=nlri_bin)
 
     @classmethod
     def construct(cls, value):
@@ -143,7 +143,7 @@ def construct(cls, value):
                     nlri = IPv4FlowSpec.construct(value=value['nlri'])
                     if nlri:
                         attr_value = struct.pack('!H', afi) + struct.pack('!B', safi) + \
-                            struct.pack('!B', len(nexthop)) + nexthop + '\x00' + nlri
+                            struct.pack('!B', len(nexthop)) + nexthop + b'\x00' + nlri
                         return struct.pack('!B', cls.FLAG) + struct.pack('!B', cls.ID) \
                             + struct.pack('!B', len(attr_value)) + attr_value
                 except Exception as e:
diff --git a/yabgp/message/attribute/nlri/ipv6_unicast.py b/yabgp/message/attribute/nlri/ipv6_unicast.py
index 8ff68d4..52a6991 100644
--- a/yabgp/message/attribute/nlri/ipv6_unicast.py
+++ b/yabgp/message/attribute/nlri/ipv6_unicast.py
@@ -31,15 +31,20 @@ def parse(nlri_data):
         """
         nlri_list = []
         while nlri_data:
-            prefix_bit_len = struct.unpack('!B', nlri_data[0])[0]
+            if isinstance(nlri_data[0], int):
+                prefix_bit_len = int(nlri_data[0])
+            else:
+                prefix_bit_len = struct.unpack('!B', nlri_data[0])[0]
+            print (type(nlri_data))
             if prefix_bit_len % 8 == 0:
                 prefix_byte_len = prefix_bit_len / 8
             else:
                 prefix_byte_len = prefix_bit_len / 8 + 1
-            prefix_addr = netaddr.IPAddress(int(binascii.b2a_hex(nlri_data[1:prefix_byte_len + 1]), 16)).__str__() \
+            offset = int(prefix_byte_len + 1)
+            prefix_addr = str(netaddr.IPAddress(int(binascii.b2a_hex(nlri_data[1:offset]), 16))) \
                 + '/%s' % prefix_bit_len
             nlri_list.append(prefix_addr)
-            nlri_data = nlri_data[prefix_byte_len + 1:]
+            nlri_data = nlri_data[int(prefix_byte_len) + 1:]
 
         return nlri_list