diff --git a/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/Constants.java b/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/Constants.java
index 763bae6..647c8e7 100644
--- a/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/Constants.java
+++ b/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/Constants.java
@@ -70,6 +70,7 @@
     public static final int CT_TABLE = 45;
     public static final int ACL_RECIRC_TABLE = 43;
     public static final int JUMP_TABLE = 50;
+    public static final int NAT_TABLE = 51;
     public static final int ROUTING_TABLE = 60;
     public static final int STAT_OUTBOUND_TABLE = 70;
     public static final int VTAP_OUTBOUND_TABLE = 71;
diff --git a/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/K8sGroupRuleService.java b/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/K8sGroupRuleService.java
new file mode 100644
index 0000000..fc935c0
--- /dev/null
+++ b/apps/k8s-networking/api/src/main/java/org/onosproject/k8snetworking/api/K8sGroupRuleService.java
@@ -0,0 +1,42 @@
+/*
+ * 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.k8snetworking.api;
+
+import org.onosproject.core.ApplicationId;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.group.GroupBucket;
+import org.onosproject.net.group.GroupDescription.Type;
+
+import java.util.List;
+
+/**
+ * Service for setting group rules.
+ */
+public interface K8sGroupRuleService {
+
+    /**
+     * Configures the group table rule.
+     *
+     * @param appId         application ID
+     * @param deviceId      device ID
+     * @param groupId       group ID
+     * @param type          group type
+     * @param buckets       a list of group buckets
+     * @param install       true for rule addition, false for rule removal
+     */
+    void setRule(ApplicationId appId, DeviceId deviceId, int groupId,
+                 Type type, List<GroupBucket> buckets, boolean install);
+}