diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Switch.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Switch.java
index 3de47ce..7552399 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Switch.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Switch.java
@@ -4,23 +4,30 @@
 
 import net.onrc.onos.ofcontroller.util.FlowEntry;
 
+/**
+ * Interface of Switch Object exposed to the "NB" read-only Topology.
+ *
+ * Everything returned by these interfaces must be either Unmodifiable view,
+ * immutable object, or a copy of the original "SB" In-memory Topology.
+ *
+ */
 public interface Switch {
 	public long getDpid();
-	
+
 	public Collection<Port> getPorts();
-	
+
 	public Port getPort(short number);
-	
-	
+
+
 	// Flows
 	public Collection<FlowEntry> getFlowEntries();
-	
+
 	// Graph traversal API
 	public Iterable<Switch> getNeighbors();
-	
+
 	public Iterable<Link> getLinks();
-	
+
 	public Link getLinkToNeighbor(long dpid);
-	
+
 	public Collection<Device> getDevices();
 }