diff --git a/perl-xCAT/xCAT/Utils.pm b/perl-xCAT/xCAT/Utils.pm
index f49fb3253..831bae20a 100644
--- a/perl-xCAT/xCAT/Utils.pm
+++ b/perl-xCAT/xCAT/Utils.pm
@@ -4711,5 +4711,4 @@ sub get_nmapversion {
     return $nmap_version;
 }
 
-
 1;
diff --git a/xCAT-server/lib/perl/xCAT/SvrUtils.pm b/xCAT-server/lib/perl/xCAT/SvrUtils.pm
index 4d0a99052..a02ca4d1c 100755
--- a/xCAT-server/lib/perl/xCAT/SvrUtils.pm
+++ b/xCAT-server/lib/perl/xCAT/SvrUtils.pm
@@ -1163,6 +1163,7 @@ sub  update_tables_with_diskless_image
         nodes: a reference to nodes array
         display: whether just display the result, if not 'yes', the result will
                  be written to the mac table.
+        nopping:  will not call pping subroutine if it set as "nopping"
     Returns:
         Return a hash with node name as key
     Globals:
@@ -1170,7 +1171,7 @@ sub  update_tables_with_diskless_image
     Error:
         none
     Example:
-        xCAT::Utils->get_mac_by_arp($nodes, $display);
+        xCAT::Utils->get_mac_by_arp($nodes, $display, $nopping);
     Comments:
 
 =cut
@@ -1178,26 +1179,28 @@ sub  update_tables_with_diskless_image
 #-------------------------------------------------------------------------------
 sub get_mac_by_arp ()
 {
-    my ($class, $nodes, $display) = @_;
+    my ($class, $nodes, $display, $nopping) = @_;
 
     my $node;
     my $data;
     my %ret = ();
     my $unreachable_nodes = "";
     my $noderange = join (',', @$nodes);
-    my @output = xCAT::Utils->runcmd("/opt/xcat/bin/pping $noderange", -1);
-
-    foreach my $line (@output) {
-        my ($hostname, $result) = split ':', $line;
-        my ($token,    $status) = split ' ', $result;
-        chomp($token);
-        if ($token eq 'ping') {
-            $node->{$hostname}->{reachable} = 1;
+    
+    if ( $nopping ne "nopping" ) {
+        my @output = xCAT::Utils->runcmd("/opt/xcat/bin/pping $noderange", -1);
+        foreach my $line (@output) {
+            my ($hostname, $result) = split ':', $line;
+            my ($token,    $status) = split ' ', $result;
+            chomp($token);
+            if ($token eq 'ping') {
+                $node->{$hostname}->{reachable} = 1;
+            }
         }
     }
 
     foreach my $n ( @$nodes ) {
-        if ( $node->{$n}->{reachable} ) {
+        if ( ( $node->{$n}->{reachable} ) || ( $nopping eq "nopping" ) ){
             my $output;
             my $IP = xCAT::NetworkUtils::toIP( $n );
             if ( xCAT::Utils->isAIX() ) {
diff --git a/xCAT-server/lib/xcat/plugins/switchdiscover.pm b/xCAT-server/lib/xcat/plugins/switchdiscover.pm
index 344997d2b..38c7e3546 100644
--- a/xCAT-server/lib/xcat/plugins/switchdiscover.pm
+++ b/xCAT-server/lib/xcat/plugins/switchdiscover.pm
@@ -13,6 +13,7 @@ use xCAT::Usage;
 use xCAT::NodeRange;
 use xCAT::NetworkUtils;
 use xCAT::Utils;
+use xCAT::SvrUtils;
 use XML::Simple;
 no strict;
 use Data::Dumper;
@@ -826,13 +827,19 @@ sub snmp_scan {
     my $ranges = get_ip_ranges($request);
 
 
-    #use nmap to find if snmp port is enabled  
-    # only open port will be scan
+    ##########################################################
+    #use nmap to parse the ip range and possible output from the command:
+    # Nmap scan report for switch-10-5-22-1 (10.5.22.1) 161/udp open  snmp
+    # Nmap scan report for 10.5.23.1 161/udp open  snmp
+    # Nmap scan report for 10.5.24.1 161/udp closed snmp  
+    # Host 10.5.23.1 appears to be up ... good. 161/udp open|filtered snmp
+    # Host 10.5.24.1 appears to be up ... good. 161/udp closed snmp
+    ##########################################################
     my $nmap_version = xCAT::Utils->get_nmapversion();
     if (xCAT::Utils->version_cmp($nmap_version,"5.10") < 0) {
-        $ccmd = "/usr/bin/nmap -P0 -v -sU -p 161 -oA snmp_scan @$ranges | grep up | grep good ";    
+        $ccmd = "/usr/bin/nmap -P0 -v -sU -p 161 -oA snmp_scan @$ranges | grep -E 'appears to be up|^161' | perl -pe 's/\\n/ / if \$. % 2'";
     } else {
-        $ccmd = "/usr/bin/nmap -P0 -v -sU -p 161 -oA snmp_scan @$ranges | grep 'open port 161' ";    
+        $ccmd = "/usr/bin/nmap -P0 -v -sU -p 161 -oA snmp_scan @$ranges | grep -v 'host down' | grep -E 'Nmap scan report|^161' | perl -pe 's/\\n/ / if \$. % 2'";
     }
     if (exists($globalopt{verbose}))    {
         send_msg($request, 0, "Process command: $ccmd\n");
@@ -855,19 +862,28 @@ sub snmp_scan {
 
     foreach my $line (@lines) {
         my @array = split / /, $line;
-        my $ip;
-        if (xCAT::Utils->version_cmp($nmap_version,"5.10") < 0) {
-            $ip = $array[1];
-        } else {
-            $ip = $array[5];
+        if ($line =~ /\b(\d{1,3}(?:\.\d{1,3}){3})\b/)
+        {
+            $ip = $1;
         }
         if (exists($globalopt{verbose}))    {
             send_msg($request, 0, "Run snmpwalk command to get information for $ip");
         }
 
+        if ($line =~ /close/) {
+            send_msg($request, 0, "*** snmp port is disabled for $ip ***");
+            next;
+        }
+
         my $vendor = get_snmpvendorinfo($request, $ip);
         if ($vendor) {
-            my $mac = get_snmpmac($request, $ip);
+            my $display = "";
+            my $nopping = "nopping";
+            my $output = xCAT::SvrUtils->get_mac_by_arp([$ip], $display, $nopping);
+            my ($desc,$mac) = split /: /, $output->{$ip};
+            if (exists($globalopt{verbose}))    {
+                send_msg($request, 0, "node: $ip, mac: $mac");
+            }
             if (!$mac) {
                 $mac="nomac_nmap_$counter";
                 $counter++;