diff --git a/incubator/protobuf/src/main/proto/Link.proto b/incubator/protobuf/src/main/proto/Link.proto
index 45b9e90..b5fcbfc 100644
--- a/incubator/protobuf/src/main/proto/Link.proto
+++ b/incubator/protobuf/src/main/proto/Link.proto
@@ -38,6 +38,20 @@
   string port_number = 2;
 }
 
+enum LinkState {
+    ACTIVE = 0;
+    INACTIVE = 1;
+}
+
+// Corresponds to org.onosproject.net.Link.
+message LinkCore {
+  LinkState state = 1;
+  ConnectPoint src = 2;
+  ConnectPoint dst = 3;
+  LinkType type = 4;
+  map<string, string> annotations = 5;
+}
+
 message LinkDescription {
   ConnectPoint src = 1;
   ConnectPoint dst = 2;