diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/NetworkGraphDatastore.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/NetworkGraphDatastore.java
index d34ac46..126d299 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/NetworkGraphDatastore.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/NetworkGraphDatastore.java
@@ -164,7 +164,7 @@
 
 	public void addLink(LinkEvent linkEvent) {
 		log.debug("Adding link {}", linkEvent);
-		
+
 		RCLink rcLink = new RCLink(linkEvent.getSrc().getDpid(), linkEvent.getSrc().getNumber(),
 				linkEvent.getDst().getDpid(), linkEvent.getDst().getNumber());
 
@@ -219,6 +219,7 @@
 				//rcDstPort.read();
 				rcLink.read();
 			} catch (ObjectDoesntExistException e) {
+			    // XXX Note: This error might be harmless, if triggered by out-dated remove Link event
 				log.error("Remove link failed {}", linkEvent, e);
 				return;
 			}