diff --git a/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.cc b/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.cc
index 124157793..132f9e5a3 100644
--- a/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.cc
+++ b/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.cc
@@ -498,6 +498,7 @@ NetTracerTechnologyComponent::NetTracerTechnologyComponent ()
 //  NetTracerConnectivity implementation
 
 NetTracerConnectivity::NetTracerConnectivity ()
+  : m_is_fallback_default (false)
 {
   // .. nothing yet ..
 }
@@ -510,6 +511,7 @@ NetTracerConnectivity::NetTracerConnectivity (const NetTracerConnectivity &d)
 NetTracerConnectivity &NetTracerConnectivity::operator= (const NetTracerConnectivity &d)
 {
   if (this != &d) {
+    m_is_fallback_default = d.m_is_fallback_default;
     m_connections = d.m_connections;
     m_symbols = d.m_symbols;
     m_name = d.m_name;
diff --git a/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.h b/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.h
index de4a10407..e8f7a8d9c 100644
--- a/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.h
+++ b/src/plugins/tools/net_tracer/db_plugin/dbNetTracerIO.h
@@ -369,6 +369,16 @@ public:
   NetTracerConnectivity (const NetTracerConnectivity &d);
   NetTracerConnectivity &operator= (const NetTracerConnectivity &d);
 
+  bool is_fallback_default () const
+  {
+    return m_is_fallback_default;
+  }
+
+  void set_fallback_default (bool f)
+  {
+    m_is_fallback_default = f;
+  }
+
   const std::string &name () const
   {
     return m_name;
@@ -491,6 +501,7 @@ private:
   std::vector<NetTracerConnectionInfo> m_connections;
   std::vector<NetTracerSymbolInfo> m_symbols;
   std::string m_name, m_description;
+  bool m_is_fallback_default;
 };
 
 class DB_PLUGIN_PUBLIC NetTracerTechnologyComponent
diff --git a/src/plugins/tools/net_tracer/db_plugin/dbNetTracerPlugin.cc b/src/plugins/tools/net_tracer/db_plugin/dbNetTracerPlugin.cc
index 3444bbe24..d5ad41a84 100644
--- a/src/plugins/tools/net_tracer/db_plugin/dbNetTracerPlugin.cc
+++ b/src/plugins/tools/net_tracer/db_plugin/dbNetTracerPlugin.cc
@@ -68,6 +68,18 @@ namespace tl
 namespace
 {
 
+static const db::NetTracerConnectivity *
+get_fallback_default (const db::NetTracerTechnologyComponent &tc)
+{
+  for (auto d = tc.begin (); d != tc.end (); ++d) {
+    if (d->is_fallback_default ()) {
+      return d.operator-> ();
+    }
+  }
+
+  return 0;
+}
+
 static const db::NetTracerConnectivity *
 get_default (const db::NetTracerTechnologyComponent &tc)
 {
@@ -88,28 +100,29 @@ get_default (const db::NetTracerTechnologyComponent &tc)
 template <class Value>
 struct FallbackXMLWriteAdaptor
 {
-  FallbackXMLWriteAdaptor (void (db::NetTracerConnectivity::*member) (const Value &), void (db::NetTracerConnectivity::*clear) ())
-    : mp_member (member), mp_clear (clear)
+  FallbackXMLWriteAdaptor (void (db::NetTracerConnectivity::*member) (const Value &))
+    : mp_member (member)
   {
     // .. nothing yet ..
   }
 
   void operator () (db::NetTracerTechnologyComponent &owner, tl::XMLReaderState &reader) const
   {
-    db::NetTracerConnectivity *stack = const_cast<db::NetTracerConnectivity *> (get_default (owner));
-    if (! stack) {
+    db::NetTracerConnectivity *stack = const_cast<db::NetTracerConnectivity *> (get_fallback_default (owner));
+    if (! stack && owner.begin () == owner.end ()) {
       owner.push_back (db::NetTracerConnectivity ());
       stack = (owner.end () - 1).operator-> ();
+      stack->set_fallback_default (true);
     }
-    (stack->*mp_clear) ();
 
-    tl::XMLObjTag<Value> tag;
-    (stack->*mp_member) (*reader.back (tag));
+    if (stack) {
+      tl::XMLObjTag<Value> tag;
+      (stack->*mp_member) (*reader.back (tag));
+    }
   }
 
 private:
   void (db::NetTracerConnectivity::*mp_member) (const Value &);
-  void (db::NetTracerConnectivity::*mp_clear) ();
 };
 
 template <class Value, class Iter>
@@ -184,10 +197,10 @@ public:
       //  Fallback readers for migrating pre-0.28 setups to 0.28 and backward compatibility
       tl::XMLMember<NetTracerConnectionInfo, NetTracerTechnologyComponent, FallbackXMLReadAdaptor <NetTracerConnectionInfo, NetTracerConnectivity::const_iterator>, FallbackXMLWriteAdaptor <NetTracerConnectionInfo>, tl::XMLStdConverter <NetTracerConnectionInfo> > (
         FallbackXMLReadAdaptor <NetTracerConnectionInfo, NetTracerConnectivity::const_iterator> (&NetTracerConnectivity::begin, &NetTracerConnectivity::end),
-        FallbackXMLWriteAdaptor <NetTracerConnectionInfo> (&NetTracerConnectivity::add, &NetTracerConnectivity::clear_connections), "connection") +
+        FallbackXMLWriteAdaptor <NetTracerConnectionInfo> (&NetTracerConnectivity::add), "connection") +
       tl::XMLMember<NetTracerSymbolInfo, NetTracerTechnologyComponent, FallbackXMLReadAdaptor <NetTracerSymbolInfo, NetTracerConnectivity::const_symbol_iterator>, FallbackXMLWriteAdaptor <NetTracerSymbolInfo>, tl::XMLStdConverter <NetTracerSymbolInfo> > (
         FallbackXMLReadAdaptor <NetTracerSymbolInfo, NetTracerConnectivity::const_symbol_iterator> (&NetTracerConnectivity::begin_symbols, &NetTracerConnectivity::end_symbols),
-        FallbackXMLWriteAdaptor <NetTracerSymbolInfo> (&NetTracerConnectivity::add_symbol, &NetTracerConnectivity::clear_symbols), "symbols")
+        FallbackXMLWriteAdaptor <NetTracerSymbolInfo> (&NetTracerConnectivity::add_symbol), "symbols")
     );
   }
 };
diff --git a/src/plugins/tools/net_tracer/db_plugin/gsiDeclDbNetTracer.cc b/src/plugins/tools/net_tracer/db_plugin/gsiDeclDbNetTracer.cc
index f9f4d1695..90fdab1ad 100644
--- a/src/plugins/tools/net_tracer/db_plugin/gsiDeclDbNetTracer.cc
+++ b/src/plugins/tools/net_tracer/db_plugin/gsiDeclDbNetTracer.cc
@@ -52,6 +52,41 @@ static void def_symbol (db::NetTracerConnectivity *tech, const std::string &name
   tech->add_symbol (db::NetTracerSymbolInfo (db::LayerProperties (name), expr));
 }
 
+static std::string get_layer_a (const db::NetTracerConnectionInfo *info)
+{
+  return info->layer_a ().to_string ();
+}
+
+static std::string get_via_layer (const db::NetTracerConnectionInfo *info)
+{
+  return info->via_layer ().to_string ();
+}
+
+static std::string get_layer_b (const db::NetTracerConnectionInfo *info)
+{
+  return info->layer_b ().to_string ();
+}
+
+gsi::Class<db::NetTracerConnectionInfo> decl_NetTracerConnectionInfo ("db", "NetTracerConnectionInfo",
+  gsi::method_ext ("layer_a", &get_layer_a, "@brief Gets the expression for the A layer") +
+  gsi::method_ext ("via_layer", &get_via_layer, "@brief Gets the expression for the Via layer") +
+  gsi::method_ext ("layer_b", &get_layer_b, "@brief Gets the expression for the B layer"),
+  "@brief Represents a single connection info line for the net tracer technology definition\n"
+  "This class has been introduced in version 0.28.3."
+);
+
+static std::string get_symbol (const db::NetTracerSymbolInfo *info)
+{
+  return info->symbol ().to_string ();
+}
+
+gsi::Class<db::NetTracerSymbolInfo> decl_NetTracerSymbolInfo ("db", "NetTracerSymbolInfo",
+  gsi::method_ext ("symbol", &get_symbol, "@brief Gets the symbol") +
+  gsi::method ("expression", &db::NetTracerSymbolInfo::expression, "@brief Gets the expression"),
+  "@brief Represents a single symbol info line for the net tracer technology definition\n"
+  "This class has been introduced in version 0.28.3."
+);
+
 gsi::Class<db::NetTracerConnectivity> decl_NetTracerConnectivity ("db", "NetTracerConnectivity",
   gsi::method ("name", &db::NetTracerConnectivity::name,
     "@brief Gets the name of the connectivty definition\n"
@@ -79,6 +114,14 @@ gsi::Class<db::NetTracerConnectivity> decl_NetTracerConnectivity ("db", "NetTrac
     "@brief Defines a symbol for use in the material expressions.\n"
     "Defines a sub-expression to be used in further symbols or material expressions. "
     "For the detailed notation of the expression see the description of the net tracer feature."
+  ) +
+  gsi::iterator ("each_connection", static_cast<db::NetTracerConnectivity::const_iterator (db::NetTracerConnectivity::*) () const> (&db::NetTracerConnectivity::begin), static_cast<db::NetTracerConnectivity::const_iterator (db::NetTracerConnectivity::*) () const> (&db::NetTracerConnectivity::end),
+    "@brief Gets the connection information.\n"
+    "This iterator method has been introduced in version 0.28.3.\n"
+  ) +
+  gsi::iterator ("each_symbol", static_cast<db::NetTracerConnectivity::const_symbol_iterator (db::NetTracerConnectivity::*) () const> (&db::NetTracerConnectivity::begin_symbols), static_cast<db::NetTracerConnectivity::const_symbol_iterator (db::NetTracerConnectivity::*) () const> (&db::NetTracerConnectivity::end_symbols),
+    "@brief Gets the symbol information.\n"
+    "This iterator method has been introduced in version 0.28.3.\n"
   ),
   "@brief A connectivity description for the net tracer\n"
   "\n"
@@ -99,6 +142,18 @@ gsi::Class<db::NetTracerConnectivity> decl_NetTracerConnectivity ("db", "NetTrac
   "has been generalized.\n"
 );
 
+DB_PUBLIC gsi::Class<db::TechnologyComponent> &decl_dbTechnologyComponent ();
+
+gsi::Class<db::NetTracerTechnologyComponent> decl_NetTracerTechnologyComponent (decl_dbTechnologyComponent (), "db", "NetTracerTechnologyComponent",
+  gsi::iterator ("each", static_cast<db::NetTracerTechnologyComponent::const_iterator (db::NetTracerTechnologyComponent::*) () const> (&db::NetTracerTechnologyComponent::begin), static_cast<db::NetTracerTechnologyComponent::const_iterator (db::NetTracerTechnologyComponent::*) () const> (&db::NetTracerTechnologyComponent::end),
+    "@brief Gets the connectivity definitions from the net tracer technology component.\n"
+  ),
+  "@brief Represents the technology information for the net tracer.\n"
+  "This class has been redefined in version 0.28 and re-introduced in version 0.28.3. Since version 0.28, "
+  "multiple stacks are supported and the individual stack definition is provided through a list of stacks. Use \\each "
+  "to iterate the stacks."
+);
+
 static void trace1 (db::NetTracer *net_tracer, const db::NetTracerConnectivity &tech, const db::Layout &layout, const db::Cell &cell, const db::Point &start_point, unsigned int start_layer)
 {
   db::NetTracerData tracer_data = tech.get_tracer_data (layout);
diff --git a/testdata/ruby/layTechnologies.rb b/testdata/ruby/layTechnologies.rb
index 26e215f9f..29ab17734 100644
--- a/testdata/ruby/layTechnologies.rb
+++ b/testdata/ruby/layTechnologies.rb
@@ -23,6 +23,14 @@ end
 
 load("test_prologue.rb")
 
+def nt_tech_to_s(t)
+  t.each.collect do |s|
+    ([ "Stack [" + s.name + "]:" ] + 
+      s.each_connection.collect { |c| " conn: " + c.layer_a + "," + c.via_layer + "," + c.layer_b } + 
+      s.each_symbol.collect { |c| " symbol: " + c.symbol + "=" + c.expression }).join("\n")
+  end.join("\n") + "\n"
+end
+
 class LAYTechnologies_TestClass < TestBase
 
   def test_1
@@ -117,7 +125,88 @@ END
 
     assert_equal(tech.component_names.size > 0, true)
     assert_equal(tech.component_names.find("connectivity") != nil, true)
-    assert_equal(tech.component("connectivity").class.to_s, "RBA::TechnologyComponent")
+    assert_equal(tech.component("connectivity").class.to_s, "RBA::NetTracerTechnologyComponent")
+
+  end
+
+  # issue 1245
+  def test_3
+
+    # empty connectivity
+    tech = RBA::Technology::technology_from_xml(<<END)
+<technology>
+  <name>X</name>
+  <connectivity/>
+</technology>
+END
+
+    nt_tech = tech.component("connectivity")
+
+    assert_equal(nt_tech_to_s(nt_tech), "\n")
+
+    # 0.27 to 0.28 migration
+    tech = RBA::Technology::technology_from_xml(<<END)
+<technology>
+  <name>X</name>
+  <connectivity>
+    <connection>11,2,3</connection>
+    <connection>14,5,6</connection>
+    <symbols>AA=17</symbols>
+    <symbols>BB=42</symbols>
+  </connectivity>
+</technology>
+END
+
+    nt_tech = tech.component("connectivity")
+
+    assert_equal(nt_tech_to_s(nt_tech), <<END)
+Stack []:
+ conn: 11,2,3
+ conn: 14,5,6
+ symbol: AA=17
+ symbol: BB=42
+END
+
+    # 0.28 way
+    tech = RBA::Technology::technology_from_xml(<<END)
+<technology>
+  <name>X</name>
+  <connectivity>
+    <stack>
+      <name>ST1</name>
+      <connection>1,2,3</connection>
+      <connection>4,5,6</connection>
+      <symbols>A=17</symbols>
+      <symbols>B=42</symbols>
+    </stack>
+    <stack>
+      <name>ST2</name>
+      <connection>1,2,3</connection>
+      <connection>4,5,7</connection>
+      <symbols>A=1</symbols>
+    </stack>
+    <!-- ignored: -->
+    <connection>1,2,3</connection>
+    <connection>4,5,6</connection>
+    <symbols>AA=17</symbols>
+    <symbols>BB=42</symbols>
+  </connectivity>
+</technology>
+END
+
+    nt_tech = tech.component("connectivity")
+
+    assert_equal(nt_tech_to_s(nt_tech), <<END)
+Stack [ST1]:
+ conn: 1,2,3
+ conn: 4,5,6
+ symbol: A=17
+ symbol: B=42
+Stack [ST2]:
+ conn: 1,2,3
+ conn: 4,5,7
+ symbol: A=1
+END
 
   end