Added a number of container classes that will be used for
Flow Path computation and installation.
diff --git a/src/main/java/net/floodlightcontroller/util/Dpid.java b/src/main/java/net/floodlightcontroller/util/Dpid.java
new file mode 100644
index 0000000..3a8d1e8
--- /dev/null
+++ b/src/main/java/net/floodlightcontroller/util/Dpid.java
@@ -0,0 +1,54 @@
+package net.floodlightcontroller.util;
+
+/**
+ * The class representing a network switch DPID.
+ */
+public class Dpid {
+    static public long UNKNOWN = 0;
+
+    private long value;
+
+    /**
+     * Default constructor.
+     */
+    public Dpid() {
+	this.value = Dpid.UNKNOWN;
+    }
+
+    /**
+     * Constructor from a long value.
+     *
+     * @param value the value to use.
+     */
+    public Dpid(long value) {
+	this.value = value;
+    }
+
+    /**
+     * Get the value of the DPID.
+     *
+     * @return the value of the DPID.
+     */
+    public long value() { return value; }
+
+    /**
+     * Set the value of the DPID.
+     *
+     * @param value the value to set.
+     */
+    public void setValue(long value) {
+	this.value = value;
+    }
+
+    /**
+     * Convert the DPID value to a ':' separated hex string.
+     *
+     * @return the DPID value as a ':' separated hex string.
+     */
+    @Override
+    public String toString() {
+	String ret = "";
+	// TODO: Implement it!
+	return ret;
+    }
+}