Return serial number for Cisco 3850 from entPhysicalSerialNum

Info/Layer3/C6500.pm

@@ -134,6 +134,23 @@ sub vendor {
 
 sub cisco_comm_indexing { return 1; }
 
+sub serial {
+    my $c6500 = shift;
+
+    my $serial = $c6500->SUPER::serial();
+    return $serial if defined $serial and $serial;
+
+    # now grab the table only if SUPER cannot find it
+    my $e_serial = $c6500->e_serial();
+
+    # Find entity table entry for this unit
+    foreach my $e ( sort keys %$e_serial ) {
+        if (defined $e_serial->{$e} and $e_serial->{$e} !~ /^\s*$/) {
+            return $e_serial->{$e};
+        }
+    }
+}
+
 #  Newer versions use the ETHERLIKE-MIB to report operational duplex.
 
 sub i_duplex {
@@ -389,6 +406,10 @@ Returns the Switch status: multiNode or standalone.
 
 Return 1 if the switch (C<cvsSwitchMode>) is in multimode (VSS).
 
+=item $c6500->serial()
+
+Returns serial number of unit (falls back to C<entPhysicalSerialNum>).
+
 =back
 
 =head2 Global Methods imported from SNMP::Info::CiscoVTP