Application manages the IP layer topology information - Interfaces

Change-Id: Ie1dea035674ee98583e98a82cca7e33ab0858b92
diff --git a/apps/iptopology-api/src/main/java/org/onosproject/iptopology/api/InterfaceIdentifier.java b/apps/iptopology-api/src/main/java/org/onosproject/iptopology/api/InterfaceIdentifier.java
new file mode 100644
index 0000000..405e141
--- /dev/null
+++ b/apps/iptopology-api/src/main/java/org/onosproject/iptopology/api/InterfaceIdentifier.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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.iptopology.api;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+
+import java.util.Objects;
+
+/**
+ * This class provides information on Local Interface Identifier and Remote
+ * Interface Identifier of the link.
+ */
+public class InterfaceIdentifier {
+    private final Integer identifier;
+
+    /**
+     * Constructor to initialize identifier.
+     *
+     * @param identifier local/remote interface identifier
+     */
+    public InterfaceIdentifier(Integer identifier) {
+        this.identifier = identifier;
+    }
+
+    /**
+     * Provides the local/remote interface identifier of the link.
+     *
+     * @return interface identifier
+     */
+    public Integer identifier() {
+        return identifier;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(identifier);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof InterfaceIdentifier) {
+            InterfaceIdentifier other = (InterfaceIdentifier) obj;
+            return Objects.equals(identifier, other.identifier);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("identifier", identifier)
+                .toString();
+    }
+}