diff --git a/ponsim/v2/protos/ponsim_olt.proto b/ponsim/v2/protos/ponsim_olt.proto
index 82214a7..3b8a761 100644
--- a/ponsim/v2/protos/ponsim_olt.proto
+++ b/ponsim/v2/protos/ponsim_olt.proto
@@ -12,6 +12,7 @@
     string id = 1;
     string address = 2;
     int32 port = 3;
+    string serial_number = 4;
 }
 
 message RegistrationReply {