diff --git a/perl-xCAT/xCAT/SLP.pm b/perl-xCAT/xCAT/SLP.pm
old mode 100644
new mode 100755
index e30c3a06e..e1ebae53b
--- a/perl-xCAT/xCAT/SLP.pm
+++ b/perl-xCAT/xCAT/SLP.pm
@@ -99,6 +99,14 @@ 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
old mode 100644
new mode 100755
index 837ffab9d..e158b693e
--- a/xCAT-client/pods/man1/lsslp.1.pod
+++ b/xCAT-client/pods/man1/lsslp.1.pod
@@ -36,6 +36,14 @@ 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.
+            If the range is huge, for example, 192.168.1.1/8, lsslp may take a very long time for node scan.
+            So the range should be exactly specified. 
+
 B<-r>          Display Raw SLP response.
 
 B<-C>          The number of the expected responses specified by the user. 
@@ -274,6 +282,8 @@ e114ngmm1:
         otherinterfaces=70.0.0.30
         hwtype=cmm
 
+10. To use lsslp unicast, enter:
+    lsslp -u -s CEC --range 40-41.1-2.1-2.1-2
 
 =head1 FILES