diff --git a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/DefaultPortPairGroup.java b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/DefaultPortPairGroup.java
index 78f41a4..9817b0a 100644
--- a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/DefaultPortPairGroup.java
+++ b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/DefaultPortPairGroup.java
@@ -24,6 +24,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 
 /**
  * Implementation of port pair group.
@@ -99,6 +100,11 @@
     }
 
     @Override
+    public Map<PortPairId, Integer> portPairLoadMap() {
+        return ImmutableMap.copyOf(portPairLoadMap);
+    }
+
+    @Override
     public int hashCode() {
         return Objects.hash(portPairGroupId, tenantId, name, description,
                             portPairList);