VOL-897 Onu Differential Reach Exceeded Alarm

        Added proto message to raise ONU differential reach
        exceeded alarm

Change-Id: Id71569c04a65b860cfef1a28897d5ba9d9d487c7
diff --git a/protos/voltha_protos/openolt.proto b/protos/voltha_protos/openolt.proto
index d2a252b..253556a 100644
--- a/protos/voltha_protos/openolt.proto
+++ b/protos/voltha_protos/openolt.proto
@@ -209,6 +209,7 @@
         OnuLossOfGEMChannelDelineationIndication onu_loss_gem_delineation_ind = 16;
         OnuPhysicalEquipmentErrorIndication onu_physical_equipment_error_ind = 17;
         OnuLossOfAcknowledgementIndication onu_loss_of_ack_ind = 18;
+        OnuDifferentialReachExceededIndication onu_diff_reach_exceeded_ind = 19;
     }
 }
 
@@ -552,6 +553,13 @@
     string status = 3;
 }
 
+message OnuDifferentialReachExceededIndication {
+        fixed32 intf_id = 1;
+        fixed32 onu_id = 2;
+        string status = 3;
+        fixed32 distance = 4;
+}
+
 message GroupMember {
     enum InterfaceType {
         PON = 0;