diff --git a/perl-xCAT/xCAT/MacMap.pm b/perl-xCAT/xCAT/MacMap.pm
index 913a5d140..de2fd64fa 100644
--- a/perl-xCAT/xCAT/MacMap.pm
+++ b/perl-xCAT/xCAT/MacMap.pm
@@ -525,6 +525,10 @@ sub refresh_switch {
     }
     unless ($session) { return; } 
     my $bridgetoifmap = walkoid($session,'.1.3.6.1.2.1.17.1.4.1.2',ciscowarn=>$iscisco); # Good for all switches
+    if (not ref $bridgetoifmap or !keys %{$bridgetoifmap}) { 
+            xCAT::MsgUtils->message("S","Error communicating with ".$session->{DestHost}.": failed to get a valid response to BRIDGE-MIB request");
+	    return;
+    }
 
     # my $mactoindexmap = walkoid($session,'.1.3.6.1.2.1.17.4.3.1.2'); 
     my $mactoindexmap = walkoid($session,'.1.3.6.1.2.1.17.7.1.2.2.1.2',silentfail=>1);
@@ -532,6 +536,10 @@ sub refresh_switch {
       #$mactoindexmap = walkoid($session,'.1.3.6.1.2.1.17.7.1.2.2.1.2');
       $mactoindexmap = walkoid($session,'.1.3.6.1.2.1.17.4.3.1.2',ciscowarn=>$iscisco); 
     } #Ok, time to process the data
+    if (not ref $mactoindexmap or !keys %{$mactoindexmap}) { 
+            xCAT::MsgUtils->message("S","Error communicating with ".$session->{DestHost}.": Unable to get MAC entries via either BRIDGE or Q-BRIDE MIB");
+	   return;
+    }
     foreach my $oid (keys %$namemap) {
     #$oid =~ m/1.3.6.1.2.1.31.1.1.1.1.(.*)/;
       my $ifindex = $oid;
diff --git a/xCAT-server/sbin/xcatd b/xCAT-server/sbin/xcatd
index a40dd1383..7521e6b22 100755
--- a/xCAT-server/sbin/xcatd
+++ b/xCAT-server/sbin/xcatd
@@ -520,6 +520,7 @@ sleep 0.05;
           $req->{'_xcat_clientip'}=inet_ntoa($client);
           $req->{'_xcat_clientport'}=$sport;
           if (defined($cmd_handlers{"findme"}) and xCAT::Utils->nodeonmynet(inet_ntoa($client))) { #only discover from ips that appear to be on a managed network
+            xCAT::MsgUtils->message("S","xcatd: Processing discovery request from ".$req->{'_clientip'});
             $req->{cacheonly}->[0] = 1;
             plugin_command($req,undef,\&build_response);
   	    if ($req->{cacheonly}->[0]) {
@@ -532,7 +533,9 @@ sleep 0.05;
            # }
 
 	    }
-          }
+          } else {
+            xCAT::MsgUtils->message("S","xcatd: Skipping discovery from ".inet_ntoa($client)." because we either have no discovery plugins or the client address does not match an IP network that xCAT is managing");
+	  }
         }
         if ($quit) { last; }
         while ($select->can_read(0)) { #grab any incoming requests during run