Add OchSignalType definition

Change-Id: I4e10f6da7d86e0a16b38ccb52c5e2514b8c60180

+/*
+ * 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.net.tunnel;
+
+/**
+ * Represents OCh (Optical Channel) signal type defined in
+ * Open Networking Foundation "Optical Transport Protocol Extensions Version 1.0".
+ */
+public enum OchSignalType {
+    /**
+     * Represents fix grid.
+     */
+    FIX_GRID,
+
+    /**
+     * Represents flex grid.
+     */
+    FLEX_GRID
+}