diff --git a/src/python/loxi/of12/util.py b/src/python/loxi/of12/util.py
index 59be12e..0159748 100644
--- a/src/python/loxi/of12/util.py
+++ b/src/python/loxi/of12/util.py
@@ -99,3 +99,10 @@
         except loxi.ProtocolError:
             return None
     return [x for x in loxi.generic_util.unpack_list(reader, deserializer) if x != None]
+
+def pack_checksum_128(value):
+    return struct.pack("!QQ", (value >> 64) & MASK64, value & MASK64)
+
+def unpack_checksum_128(reader):
+    hi, lo = reader.read("!QQ")
+    return (hi << 64) | lo