BER Driver Implementation

Change-Id: Ie215228ae4081ab0b984aafd757601a982ec84d2
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/BitErrorRateState.java b/core/api/src/main/java/org/onosproject/net/behaviour/BitErrorRateState.java
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+++ b/core/api/src/main/java/org/onosproject/net/behaviour/BitErrorRateState.java
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+/*
+ * 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.
+ *
+ * This Work is contributed by Sterlite Technologies
+ */
+package org.onosproject.net.behaviour;
+
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.driver.HandlerBehaviour;
+
+import java.util.Optional;
+
+/*
+ * Interface to compute BitErrorRate(BER) value pre and post Forward Error Correction (FEC).
+ * BER is dependent on FEC value
+ */
+public interface BitErrorRateState extends HandlerBehaviour {
+
+    /**
+     * Get the BER value pre FEC.
+     *
+     * @param deviceId the device identifier
+     * @param port     the port identifier
+     * @return the decimal value of BER
+     */
+    Optional<Double> getPreFecBer(DeviceId deviceId, PortNumber port);
+
+    /**
+     * Get the BER value post FEC.
+     *
+     * @param deviceId the device identifier
+     * @param port     the port identifier
+     * @return the decimal value of BER
+     */
+    Optional<Double> getPostFecBer(DeviceId deviceId, PortNumber port);
+}