diff --git a/app/src/main/java/org/onosproject/segmentrouting/mcast/McastCacheKey.java b/app/src/main/java/org/onosproject/segmentrouting/mcast/McastCacheKey.java
new file mode 100644
index 0000000..b0875ca
--- /dev/null
+++ b/app/src/main/java/org/onosproject/segmentrouting/mcast/McastCacheKey.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2018-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.mcast;
+
+import org.onlab.packet.IpAddress;
+import org.onosproject.net.ConnectPoint;
+
+import java.util.Objects;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Key of the multicast event cache.
+ */
+class McastCacheKey {
+    // The group ip
+    private final IpAddress mcastIp;
+    // The sink connect point
+    private final ConnectPoint sink;
+
+    /**
+     * Constructs a key for multicast event cache.
+     *
+     * @param mcastIp multicast group IP address
+     * @param sink connect point of the sink
+     */
+    public McastCacheKey(IpAddress mcastIp, ConnectPoint sink) {
+        checkNotNull(mcastIp, "mcastIp cannot be null");
+        checkNotNull(sink, "sink cannot be null");
+        checkArgument(mcastIp.isMulticast(), "mcastIp must be a multicast address");
+        this.mcastIp = mcastIp;
+        this.sink = sink;
+    }
+
+    /**
+     * Returns the multicast IP address of this key.
+     *
+     * @return multicast IP
+     */
+    public IpAddress mcastIp() {
+        return mcastIp;
+    }
+
+    /**
+     * Returns the sink of this key.
+     *
+     * @return connect point of the sink
+     */
+    public ConnectPoint sink() {
+        return sink;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof McastCacheKey)) {
+            return false;
+        }
+        McastCacheKey that =
+                (McastCacheKey) o;
+        return (Objects.equals(this.mcastIp, that.mcastIp) &&
+                Objects.equals(this.sink, that.sink));
+    }
+
+    @Override
+    public int hashCode() {
+         return Objects.hash(mcastIp, sink);
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(getClass())
+                .add("mcastIp", mcastIp)
+                .add("sink", sink)
+                .toString();
+    }
+}