diff --git a/proto/interdomain.proto b/proto/interdomain.proto
index bcbe1b11470198bbfde5de573719c520b9fc5bb5..1367bed91acb2fcadc08e8bcabcbbc9263527338 100644
--- a/proto/interdomain.proto
+++ b/proto/interdomain.proto
@@ -18,7 +18,7 @@ package interdomain;
 import "context.proto";
 
 service InterdomainService {
-  rpc Authenticate              (context.TeraFlowController) returns (context.AuthenticationResult) {}
+  rpc Authenticate              (context.TeraFlowController) returns (context.AuthenticationResult) {} // Deprecated
   rpc RequestSlice              (context.Slice             ) returns (context.SliceId             ) {}
   rpc LookUpSlice               (context.Slice             ) returns (context.SliceId             ) {}
   rpc OrderSliceFromCatalog     (context.Slice             ) returns (context.Slice               ) {}