Update Javadoc to clarify content of each Map Key
diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java b/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java
index 17566bc..b7a812c 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java
@@ -46,9 +46,9 @@
     };
 
     public long nodeId;				// The node ID
-    public HashMap<Integer, Link> links;	// The links from this node
-    private HashMap<Integer, Link> reverseLinksMap; // The links to this node
-    private HashMap<Integer, Integer> portsMap;	// The ports for this node
+    public HashMap<Integer, Link> links;	// The links from this node (src Port ID -> Link)
+    private HashMap<Integer, Link> reverseLinksMap; // The links to this node (dst Port ID -> Link)
+    private HashMap<Integer, Integer> portsMap;	// The ports on this node (Port ID -> )
 
     /**
      * Node constructor.
@@ -122,7 +122,7 @@
 
 	portsMap.remove(portId);
     }
-    
+
     /**
      * Get a link on a port to a neighbor.
      *