diff --git a/perl-xCAT/xCAT/SLP.pm b/perl-xCAT/xCAT/SLP.pm
old mode 100644
new mode 100755
index a670787e1..4f54c7667
--- a/perl-xCAT/xCAT/SLP.pm
+++ b/perl-xCAT/xCAT/SLP.pm
@@ -98,6 +98,14 @@ sub dodiscover {
     }
     my $printinfo = join(",", @printip);  
     if ($unicast) {
+        if (xCAT::Utils->isAIX()){
+            send_message($args{reqcallback}, 1, "lsslp unicast is not supported on AIX");
+            exit 1;
+        }
+        if (! -f "/usr/bin/nmap"){
+            send_message($args{reqcallback}, 1, "nmap does not exist, lsslp unicast is not possible");
+            exit 1;
+        }
         my @servernodes;
         my @iprange = split /,/, $ipranges;
         foreach my $range (@iprange) {
diff --git a/xCAT-client/pods/man1/lsslp.1.pod b/xCAT-client/pods/man1/lsslp.1.pod
index de0b96078..2dbc7b766 100644
--- a/xCAT-client/pods/man1/lsslp.1.pod
+++ b/xCAT-client/pods/man1/lsslp.1.pod
@@ -37,6 +37,7 @@ B<-h>          Display usage message.
 B<-n>          Only display and write the newly discovered hardwares.
 
 B<-u>          Do unicast to a specified IP range. Must be used with -s and --range.
+            The -u flag is not supported on AIX.
 
 B<--range>     Specify one or more IP ranges. Must be use in unicast mode. 
             It accepts multiple formats. For example, 192.168.1.1/24, 40-41.1-2.3-4.1-100.