diff --git a/.travis.yml b/.travis.yml
index ebd46574..4f36d747 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,7 +12,7 @@ before_install:
   - mkdir ~/netdisco-mibs
   - cd ~/netdisco-mibs
 install:
-  - curl -sL https://github.com/netdisco/netdisco-mibs/releases/download/4.007/netdisco-mibs.tar.gz | tar --strip-components=1 -zxf -
+  - curl -sL https://github.com/netdisco/netdisco-mibs/releases/download/4.008/netdisco-mibs.tar.gz | tar --strip-components=1 -zxf -
   - cpanm --quiet --notest PkgConfig Test::CChecker Alien::zlib::Static Alien::OpenSSL::Static Alien::SNMP::MAXTC
 before_script:
   - 'cd ${TRAVIS_BUILD_DIR}'
diff --git a/Changes b/Changes
index 982efde5..d8190fda 100644
--- a/Changes
+++ b/Changes
@@ -6,7 +6,13 @@ Version 3.55
 
   [ENHANCEMENTS]
 
-  * Increase capture of i_vlan on router interfaces in L3::Cisco 
+  * #196 Support for powerconnect 8164F
+  * Refactor Layer3::Dell for better support of newer models
+  * Increase capture of i_vlan on router interfaces in L3::Cisco
+  * Factor out logic to determine serial number from ENTITY-MIB in Layer2 and
+    Layer3 to new method entity_derived_serial in Entity class and added new
+    method entity_derived_os_ver in Entity class to determine OS version
+    in a similar manner
 
   [BUG FIXES]
 
diff --git a/lib/SNMP/Info.pm b/lib/SNMP/Info.pm
index c312b633..aeb402a6 100644
--- a/lib/SNMP/Info.pm
+++ b/lib/SNMP/Info.pm
@@ -792,7 +792,7 @@ See documentation in L<SNMP::Info::Layer3::DLink> for details.
 
 =item SNMP::Info::Layer3::Dell
 
-Subclass for Dell PowerConnect switches. D-Link, the IBM BladeCenter
+Subclass for Dell PowerConnect switches. The IBM BladeCenter
 Gigabit Ethernet Switch Module and some Linksys switches
 also use this module based upon MIB support.
 
diff --git a/lib/SNMP/Info/Layer3/Dell.pm b/lib/SNMP/Info/Layer3/Dell.pm
index 8a05d533..51e3d84b 100644
--- a/lib/SNMP/Info/Layer3/Dell.pm
+++ b/lib/SNMP/Info/Layer3/Dell.pm
@@ -50,12 +50,13 @@ $VERSION = '3.54';
     'RADLAN-rlInterfaces'            => 'rlIfNumOfLoopbackPorts',
     'RADLAN-HWENVIROMENT'            => 'rlEnvPhysicalDescription',
     'Dell-Vendor-MIB'                => 'productIdentificationVersion',
+    'DELL-REF-MIB'                   => 'dell6224Switch',
 );
 
 %GLOBALS = (
     %SNMP::Info::Layer3::GLOBALS,
     %SNMP::Info::LLDP::GLOBALS,
-    'os_ver'       => 'productIdentificationVersion',
+    'dell_os_ver'  => 'productIdentificationVersion',
     'dell_id_name' => 'productIdentificationDisplayName',
 );
 
@@ -115,16 +116,22 @@ sub model {
     my $dell = shift;
 
     my $name  = $dell->dell_id_name();
-    my $descr = $dell->description();
+    my $id    = $dell->id();
 
     if ( defined $name and $name =~ m/(\d+)/ ) {
         return $1;
     }
 
-    # Don't have a vendor MIB for D-Link
-    else {
-        return $descr;
+    return unless defined $id;
+
+    my $model = SNMP::translateObj($id);
+
+    if (defined $model) {
+        $model =~ s/^dell//;
+        $model =~ s/Switch$//;
+        return $model;
     }
+    return $id;
 }
 
 sub vendor {
@@ -139,19 +146,19 @@ sub os {
     return $dell->_vendor();
 }
 
-sub serial {
+sub os_ver {
     my $dell = shift;
 
-    my $numbers = $dell->dell_serial_no();
-
-    foreach my $key ( keys %$numbers ) {
-        my $serial = $numbers->{$key};
-        return $serial if ( defined $serial and $serial !~ /^\s*$/ );
-        next;
+    my $entity_os = $dell->entity_derived_os_ver();
+    if ( defined $entity_os and $entity_os !~ /^\s*$/ ){
+        return $entity_os;
     }
 
-    # Last resort
-    return $dell->SUPER::serial();
+    my $dell_os  = $dell->dell_os_ver();
+    if ( defined $dell_os and $dell_os !~ /^\s*$/ ) {
+        return $dell_os;
+    }
+    return;
 }
 
 # check all fans, and report overall status
@@ -160,41 +167,74 @@ sub fan {
 
     my $fan   = $dell->dell_fan_desc()  || {};
     my $state = $dell->dell_fan_state() || {};
-    my @messages = ();
+    
+    if (scalar keys %$fan) {
+        my @messages = ();
 
-    foreach my $k (keys %$fan) {
-        next if $state->{$k} and $state->{$k} eq 'normal';
-        push @messages, "$fan->{$k}: $state->{$k}";
-    }
+        foreach my $k (keys %$fan) {
+            next if $state->{$k} and $state->{$k} eq 'normal';
+            push @messages, "$fan->{$k}: $state->{$k}";
+        }
 
-    push @messages, ((scalar keys %$fan). " fans OK")
-      if scalar @messages == 0;
+        push @messages, ((scalar keys %$fan). " fans OK")
+            if scalar @messages == 0;
 
-    return (join ", ", @messages);
+        return (join ", ", @messages);
+        }
+    return;
 }
 
-sub _ps_status {
-    my ($dell, $unit) = @_;
+sub ps1_type {
+    my $dell = shift;
 
-    my $status = 'unknown';
-    return $status if !defined $unit;
+    my $src  = $dell->dell_pwr_src()  || {};
 
-    my $desc  = $dell->dell_pwr_desc()  || {};
-    my $state = $dell->dell_pwr_state() || {};
-
-    foreach my $k (keys %$desc) {
-        next unless $desc->{$k} and $desc->{$k} eq "ps1_unit$unit";
-        return ($state->{$k} || $status);
+    foreach my $k (sort keys %$src) {
+        next unless $src->{$k};
+        return $src->{$k};
     }
-
-    return $status;
+    return;
 }
 
-sub ps1_type { return 'internalRedundant' }
-sub ps2_type { return 'internalRedundant' }
+sub ps2_type {
+    my $dell = shift;
 
-sub ps1_status { return (shift)->_ps_status(1) }
-sub ps2_status { return (shift)->_ps_status(2) }
+    my $src  = $dell->dell_pwr_src()  || {};
+    
+    my $i = 0; 
+    foreach my $k (sort keys %$src) {
+        $i++;
+        next unless $src->{$k} and $i == 2;
+        return $src->{$k};
+    }
+    return;
+}
+
+sub ps1_status {
+    my $dell = shift;
+
+    my $status  = $dell->dell_pwr_state()  || {};
+
+    foreach my $k (sort keys %$status) {
+        next unless $status->{$k};
+        return $status->{$k};
+    }
+    return;
+}
+
+sub ps2_status {
+    my $dell = shift;
+
+    my $status  = $dell->dell_pwr_state()  || {};
+    
+    my $i = 0; 
+    foreach my $k (sort keys %$status) {
+        $i++;
+        next unless $status->{$k} and $i == 2;
+        return $status->{$k};
+    }
+    return;
+}
 
 sub interfaces {
     my $dell    = shift;
@@ -214,6 +254,23 @@ sub interfaces {
     return $i_descr;
 }
 
+sub i_duplex {
+    my $dell    = shift;
+    my $partial = shift;
+
+    my $dell_duplex = $dell->dell_duplex($partial) || {};
+
+    my %i_duplex;
+    foreach my $if ( keys %$dell_duplex ) {
+        my $duplex = $dell_duplex->{$if};
+        next unless defined $duplex;
+        next if $duplex eq 'unknown';
+
+        $i_duplex{$if} = $duplex;
+    }
+    return \%i_duplex;
+}
+
 sub i_duplex_admin {
     my $dell    = shift;
     my $partial = shift;
@@ -226,11 +283,11 @@ sub i_duplex_admin {
     foreach my $if ( keys %$interfaces ) {
         my $duplex = $dell_duplex->{$if};
         next unless defined $duplex;
-        my $auto = $dell_auto->{$if} || 'false';
+        my $auto = $dell_auto->{$if} || 'disabled';
 
-        $duplex = 'half' if ( $duplex =~ /half/i and $auto =~ /false/i );
-        $duplex = 'full' if ( $duplex =~ /half/i and $auto =~ /false/i );
-        $duplex = 'auto' if $auto =~ /true/i;
+        $duplex = 'half' if ( $duplex eq 'half' and $auto eq 'disabled' );
+        $duplex = 'full' if ( $duplex eq 'full' and $auto eq 'disabled' );
+        $duplex = 'auto' if $auto eq 'enabled';
         $i_duplex_admin{$if} = $duplex;
     }
     return \%i_duplex_admin;
@@ -242,7 +299,6 @@ sub _vendor {
     my $id = $dell->id() || 'undef';
     my %oidmap = (
         2    => 'ibm',
-        171  => 'dlink',
         674  => 'dell',
         3955 => 'linksys',
     );
@@ -252,7 +308,7 @@ sub _vendor {
         return $oidmap{$id};
     }
     else {
-        return 'dlink';
+        return $id;
     }
 }
 
@@ -449,6 +505,10 @@ Returns the map between SNMP Interface Identifier (iid) and physical port
 name.  Uses name if available instead of description since descriptions are 
 sometimes not unique.
 
+=item $dell->i_duplex()
+
+Returns reference to map of IIDs to current link duplex.
+
 =item $dell->i_duplex_admin()
 
 Returns reference to hash of iid to current link administrative duplex
diff --git a/xt/lib/Test/SNMP/Info/Layer3/Dell.pm b/xt/lib/Test/SNMP/Info/Layer3/Dell.pm
index 21036ac9..30ae649d 100644
--- a/xt/lib/Test/SNMP/Info/Layer3/Dell.pm
+++ b/xt/lib/Test/SNMP/Info/Layer3/Dell.pm
@@ -33,28 +33,292 @@ use Test::Class::Most parent => 'My::Test::Class';
 
 use SNMP::Info::Layer3::Dell;
 
-# Remove this startup override once we have full method coverage
-sub startup : Tests(startup => 1) {
-  my $test = shift;
-  $test->SUPER::startup();
-
-  $test->todo_methods(1);
-}
-
 sub setup : Tests(setup) {
   my $test = shift;
   $test->SUPER::setup;
 
   # Start with a common cache that will serve most tests
   my $cache_data = {
-    '_layers' => 3,
+    '_layers'      => 4,
     '_description' => 'Powerconnect 8024F, 3.1.4.5, VxWorks 6.5',
 
-    # DELL-WLAN-MIB::powerConnect.3024
-    '_id'   => '.1.3.6.1.4.1.674.10895.3024',
-    'store' => {},
+    # DELL-REF-MIB::dell8024FSwitch
+    '_id'            => '.1.3.6.1.4.1.674.10895.3024',
+    '_i_description' => 1,
+    '_i_name'        => 1,
+
+    # These don't exist in the 8024F, but pretend they do to simplify fan,
+    # ps*, and duplex_admin test code, there is no equivalent in newer models
+    '_dell_fan_desc'     => 1,
+    '_dell_fan_state'    => 1,
+    '_dell_pwr_src'      => 1,
+    '_dell_pwr_state'    => 1,
+    '_dell_pwr_desc'     => 1,
+    '_dell_duplex'       => 1,
+    '_dell_duplex_admin' => 1,
+    '_dell_auto'         => 1,
+
+    # ENTITY-MIB used for coverage of entity_derived_os_ver in os_ver
+    '_e_parent' => 1,
+    '_e_class'  => 1,
+    'store'     => {
+      'i_description' => {
+        1 => 'Ethernet Interface',
+        2 => 'Ethernet Interface',
+        3 => 'Ethernet Interface'
+      },
+      'i_name'         => {1        => 'g1',     2        => 'g2'},
+      'dell_fan_desc'  => {67109249 => 'fan1',   67109250 => 'fan2'},
+      'dell_fan_state' => {67109249 => 'normal', 67109250 => 'warning'},
+      'dell_pwr_src'   => {67109185 => 'ac',     67109186 => 'unknown'},
+      'dell_pwr_state' => {67109185 => 'normal', 67109186 => 'notPresent'},
+      'dell_pwr_desc'  => {67109185 => 'ps1',    67109186 => 'ps2'},
+      'dell_duplex'       => {1 => 'full',     2 => 'half', 3 => 'unknown'},
+      'dell_duplex_admin' => {1 => 'full',     2 => 'half', 3 => 'none'},
+      'dell_auto'         => {1 => 'disabled', 2 => 'disabled', 3 => 'enabled'},
+      'e_parent' => {1 => 0, 2 => 1, 3 => 2, 54 => 1, 55 => 54},
+      'e_class'  => {
+        1  => 'stack',
+        2  => 'chassis',
+        3  => 'module',
+        54 => 'chassis',
+        55 => 'module'
+      },
+    },
   };
   $test->{info}->cache($cache_data);
 }
 
+# This class is also used for devices that don't have the Dell IANA private
+# enterprise number (674). If we ever create a new class to cover these
+# devices these tests should serve as a reminder to remove the applicable
+# from this class
+sub device_type : Tests(+2) {
+  my $test = shift;
+  $test->SUPER::device_type();
+
+  # IBM BladeCenter 4-Port GB Ethernet Switch Module
+  my $cache_data = {
+    '_layers'      => 2,
+    '_description' => 'IBM Gigabit Ethernet Switch Module',
+    '_id'          => '.1.3.6.1.4.1.2'
+  };
+  $test->{info}->cache($cache_data);
+  is($test->{info}->device_type,
+    'SNMP::Info::Layer3::Dell',
+    'IBM BladeCenter 4-Port GB Ethernet Switch Module');
+  $test->{info}->clear_cache();
+
+  # Linksys 2024/2048
+  $cache_data = {
+    '_layers'      => 2,
+    '_description' => '48-Port 10/100/1000 Gigabit Switch w/WebView',
+    '_id'          => '.1.3.6.1.4.1.3955.6.1.2024.1'
+  };
+  $test->{info}->cache($cache_data);
+  is($test->{info}->device_type,
+    'SNMP::Info::Layer3::Dell', 'Linksys 2024/2048');
+  $test->{info}->clear_cache();
+}
+
+sub model : Tests(5) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'model');
+
+  is($test->{info}->model(),
+    '8024F', q(Model has expected value using 'sysObjectID'));
+
+  # Non Dell sysObjectID's won't resolve and should return a partially
+  # resolved OID
+  $test->{info}{_id} = '.1.3.6.1.4.1.3955.6.1.2024.1';
+  is($test->{info}->model(),
+    'enterprises.3955.6.1.2024.1',
+    q(Non Dell returns partially resolved 'sysObjectID'));
+
+  # On older switches, sysObjectID will not resolve, this is from
+  # Dell-Vendor-MIB::productIdentificationDisplayName which is not populated
+  # on newer models such as the dell8024FSwitch which snmp data is in the
+  # test setup method to populate the default cache
+  $test->{info}{_dell_id_name} = 'PowerConnect 5324';
+  is($test->{info}->model(),
+    '5324', q(Older 'productIdentificationDisplayName' returns expected model));
+
+  $test->{info}->clear_cache();
+  is($test->{info}->model(), undef, q(No id returns undef model));
+}
+
+sub vendor : Tests(5) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'vendor');
+  is($test->{info}->vendor(), 'dell', q(Vendor returns 'dell'));
+
+  $test->{info}{_id} = '.1.3.6.1.4.1.3955.6.1.2024.1';
+  is($test->{info}->vendor(), 'linksys', q(Vendor returns 'linksys'));
+
+  $test->{info}{_id} = '.1.3.6.1.4.1.2';
+  is($test->{info}->vendor(), 'ibm', q(Vendor returns 'ibm'));
+
+  $test->{info}->clear_cache();
+  is($test->{info}->vendor(),
+    'undef', q(No 'sysObjectID' returns 'undef' string));
+}
+
+sub os : Tests(5) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'os');
+  is($test->{info}->os(), 'dell', q(OS returns 'dell'));
+
+  $test->{info}{_id} = '.1.3.6.1.4.1.3955.6.1.2024.1';
+  is($test->{info}->os(), 'linksys', q(OS returns 'linksys'));
+
+  $test->{info}{_id} = '.1.3.6.1.4.1.2';
+  is($test->{info}->os(), 'ibm', q(OS returns 'ibm'));
+
+  $test->{info}->clear_cache();
+  is($test->{info}->os(), 'undef', q(No 'sysObjectID' returns 'undef' string));
+}
+
+sub os_ver : Tests(4) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'os_ver');
+
+  # The call to SUPER::serial() will use the entity_derived_serial method
+  # which uses a partial fetch for e_serial which ignores the cache
+  # and reloads data therefore we must use the mocked session.
+  my $data
+    = {'ENTITY-MIB::entPhysicalSoftwareRev' =>
+      {1 => undef, 2 => '5.1.2.3', 3 => undef, 54 => '6.1.2.3', 55 => undef},
+    };
+  $test->{info}{sess}{Data} = $data;
+
+  is($test->{info}->os_ver(),
+    '5.1.2.3', q(OS version has expected value using 'ENTITY-MIB'));
+
+  $test->{info}->clear_cache();
+
+  # Manually populate cache entry
+  $test->{info}{_dell_os_ver} = '1.0.0.45';
+  is($test->{info}->os_ver(),
+    '1.0.0.45',
+    q(OS version has expected value using 'productIdentificationVersion'));
+
+  $test->{info}->clear_cache();
+  is($test->{info}->os_ver(), undef, q(No data retruns undef));
+}
+
+sub fan : Tests(4) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'fan');
+  is($test->{info}->fan(), 'fan2: warning', q(Returns fan not in normal state));
+
+  # All fans normal returns a distinct string for this class
+  $test->{info}{store}{dell_fan_state}
+    = {67109249 => 'normal', 67109250 => 'normal'};
+  is($test->{info}->fan(), '2 fans OK', q(All fans ok));
+
+  $test->{info}->clear_cache();
+  is($test->{info}->fan(), undef, q(No fan data returns undef));
+}
+
+sub ps1_type : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'ps1_type');
+  is($test->{info}->ps1_type(), 'ac');
+
+  $test->{info}->clear_cache();
+  is($test->{info}->ps1_type(),
+    undef, q(No power supply data returns type undef));
+}
+
+sub ps2_type : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'ps2_type');
+  is($test->{info}->ps2_type(), 'unknown');
+
+  $test->{info}->clear_cache();
+  is($test->{info}->ps2_type(),
+    undef, q(No power supply data returns type undef));
+}
+
+sub ps1_status : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'ps1_status');
+  is($test->{info}->ps1_status(), 'normal');
+
+  $test->{info}->clear_cache();
+  is($test->{info}->ps1_status(),
+    undef, q(No power supply data returns status undef));
+}
+
+sub ps2_status : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'ps2_status');
+  is($test->{info}->ps2_status(), 'notPresent');
+
+  $test->{info}->clear_cache();
+  is($test->{info}->ps2_status(),
+    undef, q(No power supply data returns status undef));
+}
+
+sub interfaces : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'interfaces');
+
+  my $expected = {1 => 'g1', 2 => 'g2', 3 => 'Ethernet Interface'};
+
+  cmp_deeply($test->{info}->interfaces(),
+    $expected, q(Interfaces have expected values));
+
+  $test->{info}->clear_cache();
+  cmp_deeply($test->{info}->interfaces(), {}, q(No data returns empty hash));
+}
+
+sub i_duplex : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'i_duplex');
+
+  my $expected = {1 => 'full', 2 => 'half'};
+
+  cmp_deeply($test->{info}->i_duplex(),
+    $expected, q(Interfaces have expected duplex values));
+
+  $test->{info}->clear_cache();
+  cmp_deeply($test->{info}->i_duplex(),
+    {}, q(No duplex admin data returns empty hash));
+}
+
+sub i_duplex_admin : Tests(3) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'i_duplex_admin');
+
+  my $expected = {1 => 'full', 2 => 'half', 3 => 'auto'};
+
+  cmp_deeply($test->{info}->i_duplex_admin(),
+    $expected, q(Interfaces have expected duplex admin values));
+
+  $test->{info}->clear_cache();
+  cmp_deeply($test->{info}->i_duplex_admin(),
+    {}, q(No duplex admin data returns empty hash));
+}
+
+sub qb_fdb_index : Tests(2) {
+  my $test = shift;
+
+  can_ok($test->{info}, 'qb_fdb_index');
+  is($test->{info}->qb_fdb_index(), undef);
+
+}
+
 1;