Added graph-related utility code.
diff --git a/utils/misc/src/main/java/org/onlab/graph/Edge.java b/utils/misc/src/main/java/org/onlab/graph/Edge.java
new file mode 100644
index 0000000..d4031f5
--- /dev/null
+++ b/utils/misc/src/main/java/org/onlab/graph/Edge.java
@@ -0,0 +1,24 @@
+package org.onlab.graph;
+
+/**
+ * Representation of a graph edge.
+ *
+ * @param <V> vertex type
+ */
+public interface Edge<V extends Vertex> {
+
+ /**
+ * Returns the edge source vertex.
+ *
+ * @return source vertex
+ */
+ V src();
+
+ /**
+ * Returns the edge destination vertex.
+ *
+ * @return destination vertex
+ */
+ V dst();
+
+}