diff --git a/core/api/src/main/java/org/onosproject/net/AnnotationKeys.java b/core/api/src/main/java/org/onosproject/net/AnnotationKeys.java
index d3157e1..da93417 100644
--- a/core/api/src/main/java/org/onosproject/net/AnnotationKeys.java
+++ b/core/api/src/main/java/org/onosproject/net/AnnotationKeys.java
@@ -122,6 +122,16 @@
     public static final String PORT_NAME = "portName";
 
     /**
+     * Annotation key for the optical channel receiving/in port (RX).
+     */
+    public static final String PORT_IN = "portIn";
+
+    /**
+     * Annotation key for the optical channel port transmitting/out port (TX).
+     */
+
+    public static final String PORT_OUT = "portOut";
+    /**
      * Annotation key for the port mac.
      */
     public static final String PORT_MAC = "portMac";