diff --git a/apps/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java b/apps/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java
index bea0fd5..926809c 100644
--- a/apps/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java
+++ b/apps/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java
@@ -15,6 +15,14 @@
  */
 package org.onosproject.vtnrsc.virtualport.impl;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import java.util.stream.Collectors;
+
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -43,13 +51,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Map;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
 /**
  * Provides implementation of the VirtualPort APIs.
  */
@@ -131,37 +132,22 @@
     @Override
     public Collection<VirtualPort> getPorts(TenantNetworkId networkId) {
         checkNotNull(networkId, NETWORKID_NOT_NULL);
-        Collection<VirtualPort> vPortWithNetworkIds = vPortStore.values();
-        for (VirtualPort vPort : vPortWithNetworkIds) {
-            if (!vPort.networkId().equals(networkId)) {
-                vPortWithNetworkIds.remove(vPort);
-            }
-        }
-        return vPortWithNetworkIds;
+        return vPortStore.values().stream().filter(d -> d.networkId().equals(networkId))
+                .collect(Collectors.toList());
     }
 
     @Override
     public Collection<VirtualPort> getPorts(TenantId tenantId) {
         checkNotNull(tenantId, TENANTID_NOT_NULL);
-        Collection<VirtualPort> vPortWithTenantIds = vPortStore.values();
-        for (VirtualPort vPort : vPortWithTenantIds) {
-            if (!vPort.tenantId().equals(tenantId)) {
-                vPortWithTenantIds.remove(vPort);
-            }
-        }
-        return vPortWithTenantIds;
+        return vPortStore.values().stream().filter(d -> d.tenantId().equals(tenantId))
+                .collect(Collectors.toList());
     }
 
     @Override
     public Collection<VirtualPort> getPorts(DeviceId deviceId) {
         checkNotNull(deviceId, DEVICEID_NOT_NULL);
-        Collection<VirtualPort> vPortWithDeviceIds = vPortStore.values();
-        for (VirtualPort vPort : vPortWithDeviceIds) {
-            if (!vPort.deviceId().equals(deviceId)) {
-                vPortWithDeviceIds.remove(vPort);
-            }
-        }
-        return vPortWithDeviceIds;
+        return vPortStore.values().stream().filter(d -> d.deviceId().equals(deviceId))
+                .collect(Collectors.toList());
     }
 
     @Override