diff --git a/app/src/test/java/org/onosproject/segmentrouting/config/DeviceConfigurationTest.java b/app/src/test/java/org/onosproject/segmentrouting/config/DeviceConfigurationTest.java
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+++ b/app/src/test/java/org/onosproject/segmentrouting/config/DeviceConfigurationTest.java
@@ -0,0 +1,160 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.segmentrouting.config;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.packet.IpPrefix;
+import org.onlab.packet.MacAddress;
+import org.onlab.packet.VlanId;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.config.NetworkConfigRegistry;
+import org.onosproject.net.config.basics.InterfaceConfig;
+import org.onosproject.net.host.InterfaceIpAddress;
+import org.onosproject.net.intf.Interface;
+import org.onosproject.net.intf.InterfaceService;
+import org.onosproject.net.neighbour.NeighbourResolutionService;
+import org.onosproject.segmentrouting.SegmentRoutingManager;
+
+import java.io.InputStream;
+import java.util.List;
+import java.util.Set;
+
+import static org.easymock.EasyMock.anyObject;
+import static org.easymock.EasyMock.createMock;
+import static org.easymock.EasyMock.eq;
+import static org.easymock.EasyMock.expect;
+import static org.easymock.EasyMock.expectLastCall;
+import static org.easymock.EasyMock.replay;
+import static org.junit.Assert.*;
+
+public class DeviceConfigurationTest {
+    private static final DeviceId DEV1 = DeviceId.deviceId("of:1");
+    private static final String CONFIG_KEY = "segmentrouting";
+    private static final PortNumber PORT1 = PortNumber.portNumber(1);
+    private static final PortNumber PORT2 = PortNumber.portNumber(2);
+    private static final ConnectPoint CP1 = new ConnectPoint(DEV1, PORT1);
+    private static final ConnectPoint CP2 = new ConnectPoint(DEV1, PORT2);
+    private static final MacAddress MAC1 = MacAddress.valueOf("00:11:22:33:44:55");
+    private static final VlanId VLAN1 = VlanId.vlanId((short) 10);
+    private static final VlanId VLAN2 = VlanId.vlanId((short) 20);
+    private static final IpPrefix PREFIX1 = IpPrefix.valueOf("10.0.1.254/24");
+    private static final IpPrefix PREFIX2 = IpPrefix.valueOf("10.0.2.254/24");
+    private static final IpPrefix ROUTE1 = IpPrefix.valueOf("20.0.1.254/24");
+    private static final InterfaceIpAddress INTF1_IP = new InterfaceIpAddress(PREFIX1.address(), PREFIX1);
+    private static final InterfaceIpAddress INTF2_IP = new InterfaceIpAddress(PREFIX2.address(), PREFIX2);
+    private static final List<InterfaceIpAddress> IP_LIST1 = Lists.newArrayList(INTF1_IP);
+    private static final List<InterfaceIpAddress> IP_LIST2 = Lists.newArrayList(INTF2_IP);
+    private static final Interface INTF1 = new Interface("mock-intf1", CP1, IP_LIST1, MAC1,
+            null, VLAN1, null, null);
+    private static final Interface INTF2 = new Interface("mock-intf2", CP2, IP_LIST2, MAC1,
+            null, VLAN2, null, null);
+    private static final Set<Interface> INTERFACES = Sets.newHashSet(INTF1, INTF2);
+
+    private DeviceConfiguration devConfig;
+
+    @Before
+    public void setUp() throws Exception {
+        InterfaceService interfaceService;
+        NetworkConfigRegistry networkConfigService;
+        NeighbourResolutionService neighbourResolutionService;
+        SegmentRoutingManager srManager;
+
+        // Mock device netcfg
+        InputStream jsonStream = SegmentRoutingDeviceConfigTest.class.getResourceAsStream("/device.json");
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode jsonNode = mapper.readTree(jsonStream);
+        SegmentRoutingDeviceConfig srDevConfig = new SegmentRoutingDeviceConfig();
+        srDevConfig.init(DEV1, CONFIG_KEY, jsonNode, mapper, config -> { });
+
+        // Mock interface netcfg
+        jsonStream = InterfaceConfig.class.getResourceAsStream("/interface1.json");
+        jsonNode = mapper.readTree(jsonStream);
+        InterfaceConfig interfaceConfig1 = new InterfaceConfig();
+        interfaceConfig1.init(CP1, CONFIG_KEY, jsonNode, mapper, config -> { });
+        jsonStream = InterfaceConfig.class.getResourceAsStream("/interface2.json");
+        jsonNode = mapper.readTree(jsonStream);
+        InterfaceConfig interfaceConfig2 = new InterfaceConfig();
+        interfaceConfig2.init(CP1, CONFIG_KEY, jsonNode, mapper, config -> { });
+
+        networkConfigService = createMock(NetworkConfigRegistry.class);
+        expect(networkConfigService.getSubjects(DeviceId.class, SegmentRoutingDeviceConfig.class))
+                .andReturn(Sets.newHashSet(DEV1)).anyTimes();
+        expect(networkConfigService.getConfig(DEV1, SegmentRoutingDeviceConfig.class))
+                .andReturn(srDevConfig).anyTimes();
+        expect(networkConfigService.getSubjects(ConnectPoint.class, InterfaceConfig.class))
+                .andReturn(Sets.newHashSet(CP1, CP2)).anyTimes();
+        expect(networkConfigService.getConfig(CP1, InterfaceConfig.class)).andReturn(interfaceConfig1).anyTimes();
+        expect(networkConfigService.getConfig(CP2, InterfaceConfig.class)).andReturn(interfaceConfig2).anyTimes();
+        expect(networkConfigService.applyConfig(eq(CP1), eq(InterfaceConfig.class), anyObject()))
+                .andReturn(interfaceConfig1).anyTimes();
+        expect(networkConfigService.applyConfig(eq(CP2), eq(InterfaceConfig.class), anyObject()))
+                .andReturn(interfaceConfig2).anyTimes();
+        expect(networkConfigService.getConfig(null, SegmentRoutingAppConfig.class)).andReturn(null).anyTimes();
+        replay(networkConfigService);
+
+        interfaceService = createMock(InterfaceService.class);
+        expect(interfaceService.getInterfaces()).andReturn(INTERFACES).anyTimes();
+        expect(interfaceService.getInterfacesByPort(CP1)).andReturn(Sets.newHashSet(INTF1)).anyTimes();
+        expect(interfaceService.getInterfacesByPort(CP2)).andReturn(Sets.newHashSet(INTF2)).anyTimes();
+        replay(interfaceService);
+
+        neighbourResolutionService = createMock(NeighbourResolutionService.class);
+        neighbourResolutionService.registerNeighbourHandler(anyObject(ConnectPoint.class), anyObject(), anyObject());
+        expectLastCall().anyTimes();
+        replay(neighbourResolutionService);
+
+        srManager = new SegmentRoutingManager();
+        srManager.interfaceService = interfaceService;
+        srManager.cfgService = networkConfigService;
+        srManager.neighbourResolutionService = neighbourResolutionService;
+
+        devConfig = new DeviceConfiguration(srManager);
+        devConfig.addSubnet(CP2, ROUTE1);
+    }
+
+    @Test
+    public void getConfiguredSubnets() {
+        Set<IpPrefix> expect = Sets.newHashSet(PREFIX1, PREFIX2);
+        assertEquals(expect, devConfig.getConfiguredSubnets(DEV1));
+    }
+
+    @Test
+    public void getSubnets() {
+        Set<IpPrefix> expect = Sets.newHashSet(PREFIX1, PREFIX2, ROUTE1);
+        assertEquals(expect, devConfig.getSubnets(DEV1));
+    }
+
+    @Test
+    public void getPortSubnets() {
+        assertEquals(Sets.newHashSet(PREFIX1), devConfig.getPortSubnets(DEV1, PORT1));
+        assertEquals(Sets.newHashSet(PREFIX2), devConfig.getPortSubnets(DEV1, PORT2));
+    }
+
+    @Test
+    public void inSameSubnet() {
+        assertTrue(devConfig.inSameSubnet(DEV1, PREFIX1.address()));
+        assertTrue(devConfig.inSameSubnet(DEV1, PREFIX2.address()));
+        assertFalse(devConfig.inSameSubnet(DEV1, ROUTE1.address()));
+    }
+}
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