diff --git a/network.metrics/src/metrics/embedding/ActiveSubstrateSwitchMetric.java b/network.metrics/src/metrics/embedding/ActiveSubstrateSwitchMetric.java
index 72c161f2..6d2db908 100644
--- a/network.metrics/src/metrics/embedding/ActiveSubstrateSwitchMetric.java
+++ b/network.metrics/src/metrics/embedding/ActiveSubstrateSwitchMetric.java
@@ -28,7 +28,7 @@ public ActiveSubstrateSwitchMetric(final SubstrateNetwork sNet) {
 
     for (final Node n : facade.getAllSwitchesOfNetwork(sNet.getName())) {
       final SubstrateSwitch sw = (SubstrateSwitch) n;
-      if (!sw.getGuestSwitches().isEmpty() || !sw.getGuestLinks().isEmpty()) {
+      if (!sw.getGuestSwitches().isEmpty()) {
         value++;
       }
     }
diff --git a/network.model/model/Model.ecore b/network.model/model/Model.ecore
index 07f1053b..7413ce96 100644
--- a/network.model/model/Model.ecore
+++ b/network.model/model/Model.ecore
@@ -137,12 +137,6 @@
     <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
       <details key="documentation" value="Abstract class that represents a substrate element."/>
     </eAnnotations>
-    <eStructuralFeatures xsi:type="ecore:EReference" name="guestLinks" upperBound="-1"
-        eType="#//VirtualLink" eOpposite="#//VirtualLink/host">
-      <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
-        <details key="documentation" value="Virtual guest links."/>
-      </eAnnotations>
-    </eStructuralFeatures>
   </eClassifiers>
   <eClassifiers xsi:type="ecore:EClass" name="SubstrateNode" abstract="true" eSuperTypes="#//Node #//SubstrateElement">
     <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
@@ -173,7 +167,18 @@
       </eAnnotations>
     </eStructuralFeatures>
   </eClassifiers>
-  <eClassifiers xsi:type="ecore:EClass" name="SubstrateServer" eSuperTypes="#//Server #//SubstrateNode">
+  <eClassifiers xsi:type="ecore:EClass" name="SubstrateHostLink" abstract="true" eSuperTypes="#//SubstrateElement">
+    <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
+      <details key="documentation" value="Abstract class that can host a virtual link."/>
+    </eAnnotations>
+    <eStructuralFeatures xsi:type="ecore:EReference" name="guestLinks" upperBound="-1"
+        eType="#//VirtualLink" eOpposite="#//VirtualLink/host">
+      <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
+        <details key="documentation" value="Virtual guest links."/>
+      </eAnnotations>
+    </eStructuralFeatures>
+  </eClassifiers>
+  <eClassifiers xsi:type="ecore:EClass" name="SubstrateServer" eSuperTypes="#//Server #//SubstrateNode #//SubstrateHostLink">
     <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
       <details key="documentation" value="Class that represents a substrate server."/>
     </eAnnotations>
@@ -213,7 +218,7 @@
       <details key="documentation" value="Class that represents a substrate switch."/>
     </eAnnotations>
   </eClassifiers>
-  <eClassifiers xsi:type="ecore:EClass" name="SubstrateLink" eSuperTypes="#//Link #//SubstrateElement">
+  <eClassifiers xsi:type="ecore:EClass" name="SubstrateLink" eSuperTypes="#//Link #//SubstrateElement #//SubstrateHostLink">
     <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
       <details key="documentation" value="Class that represents a substrate link."/>
     </eAnnotations>
@@ -230,7 +235,7 @@
       </eAnnotations>
     </eStructuralFeatures>
   </eClassifiers>
-  <eClassifiers xsi:type="ecore:EClass" name="SubstratePath" eSuperTypes="#//SubstrateElement">
+  <eClassifiers xsi:type="ecore:EClass" name="SubstratePath" eSuperTypes="#//SubstrateElement #//SubstrateHostLink">
     <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
       <details key="documentation" value="Class that represents a substrate path."/>
     </eAnnotations>
@@ -335,8 +340,8 @@
     <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
       <details key="documentation" value="Class that represents a virtual link."/>
     </eAnnotations>
-    <eStructuralFeatures xsi:type="ecore:EReference" name="host" lowerBound="1" eType="#//SubstrateElement"
-        eOpposite="#//SubstrateElement/guestLinks">
+    <eStructuralFeatures xsi:type="ecore:EReference" name="host" lowerBound="1" eType="#//SubstrateHostLink"
+        eOpposite="#//SubstrateHostLink/guestLinks">
       <eAnnotations source="http://www.eclipse.org/emf/2002/GenModel">
         <details key="documentation" value="Substrate host element."/>
       </eAnnotations>
diff --git a/network.model/model/Model.emf b/network.model/model/Model.emf
index 9d31e331..02b64507 100644
--- a/network.model/model/Model.emf
+++ b/network.model/model/Model.emf
@@ -74,10 +74,7 @@ abstract class Network extends Element {
 }
 
 @GenModel(documentation="Abstract class that represents a substrate element.")
-abstract class SubstrateElement extends Element {
-	// Keep in mind: The host element must not be a switch!
-	@GenModel(documentation="Virtual guest links.")
-	ref VirtualLink [*]#host guestLinks;
+abstract class SubstrateElement extends Element {
 }
 
 @GenModel(documentation="Abstract class that represents a substrate node.")
@@ -95,8 +92,14 @@ abstract class SubstrateNode extends Node, SubstrateElement {
 	ref SubstratePath [*]#target incomingPaths;
 }
 
+@GenModel(documentation="Abstract class that can host a virtual link.")
+abstract class SubstrateHostLink extends SubstrateElement {
+	@GenModel(documentation="Virtual guest links.")
+	ref VirtualLink [*]#host guestLinks;
+}
+
 @GenModel(documentation="Class that represents a substrate server.")
-class SubstrateServer extends Server, SubstrateNode {
+class SubstrateServer extends Server, SubstrateNode, SubstrateHostLink {
 	@GenModel(documentation="Virtual guest servers.")
 	ref VirtualServer [*]#host guestServers;
 	
@@ -120,7 +123,7 @@ class SubstrateSwitch extends Switch, SubstrateNode {
 }
 
 @GenModel(documentation="Class that represents a substrate link.")
-class SubstrateLink extends Link, SubstrateElement {
+class SubstrateLink extends Link, SubstrateElement, SubstrateHostLink {
 	@GenModel(documentation="Residual bandwidth amount of this link.")
 	attr EInt [1] residualBandwidth;
 	
@@ -129,7 +132,7 @@ class SubstrateLink extends Link, SubstrateElement {
 }
 
 @GenModel(documentation="Class that represents a substrate path.")
-class SubstratePath extends SubstrateElement {
+class SubstratePath extends SubstrateElement, SubstrateHostLink {
 	@GenModel(documentation="Network this path belongs to.") 
 	ref SubstrateNetwork [1]#paths network;
 	
@@ -188,9 +191,8 @@ class VirtualSwitch extends Switch, VirtualNode {
 
 @GenModel(documentation="Class that represents a virtual link.")
 class VirtualLink extends Link, VirtualElement {
-	// Keep in mind: The host element must not be a switch!
 	@GenModel(documentation="Substrate host element.")
-	ref SubstrateElement [1]#guestLinks host;
+	ref SubstrateHostLink [1]#guestLinks host;
 }
 
 @GenModel(documentation="Represents a virtual network.")
diff --git a/network.model/src/facade/ModelFacade.java b/network.model/src/facade/ModelFacade.java
index a4420312..13bd21e8 100644
--- a/network.model/src/facade/ModelFacade.java
+++ b/network.model/src/facade/ModelFacade.java
@@ -25,7 +25,7 @@
 import model.Node;
 import model.Root;
 import model.Server;
-import model.SubstrateElement;
+import model.SubstrateHostLink;
 import model.SubstrateLink;
 import model.SubstrateNetwork;
 import model.SubstrateNode;
@@ -1269,7 +1269,7 @@ public void unembedVirtualNetwork(final VirtualNetwork vNet) {
 
       for (final Link l : vNet.getLinks()) {
         final VirtualLink vl = (VirtualLink) l;
-        final SubstrateElement host = vl.getHost();
+        final SubstrateHostLink host = vl.getHost();
         if (host == null) {
           continue;
         }