diff --git a/libsrc/core/mpi_wrapper.hpp b/libsrc/core/mpi_wrapper.hpp
index b258eda4..7e55faf5 100644
--- a/libsrc/core/mpi_wrapper.hpp
+++ b/libsrc/core/mpi_wrapper.hpp
@@ -101,20 +101,52 @@ namespace ngcore
     
     operator MPI_Comm() const { return comm; }
 
-    int Rank() const { return rank; } // int r; MPI_Comm_rank(comm, &r); return r; }
-    int Size() const { return size; } // int s; MPI_Comm_size(comm, &s); return s; }
+    int Rank() const { return rank; }
+    int Size() const { return size; }
+    void Barrier() const {
+      if (size > 1) MPI_Barrier (comm);
+    }
+    
 
 
     template<typename T, typename T2 = decltype(GetMPIType<T>())>
-    void Send( T & val, int dest, int tag) {
+    void Send (T & val, int dest, int tag) const {
       MPI_Send (&val, 1, GetMPIType<T>(), dest, tag, comm);
     }
     
     template<typename T, typename T2 = decltype(GetMPIType<T>())> 
-    void MyMPI_Recv (T & val, int src, int tag) {
+    void MyMPI_Recv (T & val, int src, int tag) const {
       MPI_Recv (&val, 1, GetMPIType<T>(), src, tag, comm, MPI_STATUS_IGNORE);
     }
 
+
+    /** --- collectives --- **/
+
+    template <typename T, typename T2 = decltype(GetMPIType<T>())> 
+    T AllReduce (T d, const MPI_Op & op) const
+    {
+      if (size == 1) return d;
+      
+      T global_d;
+      MPI_Allreduce ( &d, &global_d, 1, GetMPIType<T>(), op, comm);
+      return global_d;
+    }
+
+    template <typename T, typename T2 = decltype(GetMPIType<T>())> 
+    void Bcast (T & s, int root = 0) const {
+      if (size == 1) return ;
+      MPI_Bcast (&s, 1, GetMPIType<T>(), root, comm);
+    }
+    
+    void Bcast (std::string & s, int root = 0) const 
+    {
+      if (size == 1) return;
+      int len = s.length();
+      Bcast (len, root);
+      if (rank != 0) s.resize (len);
+      MPI_Bcast (&s[0], len, MPI_CHAR, root, comm);
+    }
+
     
   };
 
@@ -138,14 +170,20 @@ namespace ngcore
 
     size_t Rank() const { return 0; }
     size_t Size() const { return 1; }
-
+    void Barrier() const { ; } 
     operator MPI_Comm() const { return MPI_Comm(); }
 
     template<typename T>
-    void Send( T & val, int dest, int tag) { ; }
+    void Send( T & val, int dest, int tag) const { ; }
     
     template<typename T>
-    void MyMPI_Recv (T & val, int src, int tag) { ; }
+    void MyMPI_Recv (T & val, int src, int tag) const { ; }
+
+    template <typename T, typename T2 = decltype(GetMPIType<T>())> 
+    T AllReduce (T d, const MPI_Op & op) const { return d; }
+
+    template <typename T, typename T2 = decltype(GetMPIType<T>())> 
+    INLINE void Bcast (T & s, int root = 0) const { ; } 
   };  
   
 #endif
diff --git a/libsrc/general/mpi_interface.hpp b/libsrc/general/mpi_interface.hpp
index 15e13171..6dc3070f 100644
--- a/libsrc/general/mpi_interface.hpp
+++ b/libsrc/general/mpi_interface.hpp
@@ -14,8 +14,8 @@
 
 namespace netgen
 {
-  using ngcore::id;
-  using ngcore::ntasks;
+  // using ngcore::id;
+  // using ngcore::ntasks;
 
 #ifndef PARALLEL
   /** without MPI, we need a dummy typedef **/
@@ -23,16 +23,17 @@ namespace netgen
 #endif
 
   /** This is the "standard" communicator that will be used for netgen-objects. **/
-  extern DLL_HEADER NgMPI_Comm ng_comm;
+  // extern DLL_HEADER NgMPI_Comm ng_comm;
 
+#ifdef OLD
 #ifdef PARALLEL
-  inline int MyMPI_GetNTasks (MPI_Comm comm = ng_comm)
+  inline int MyMPI_GetNTasks (MPI_Comm comm /* = ng_comm */)
   {
     int ntasks;
     MPI_Comm_size(comm, &ntasks);
     return ntasks;
   }
-  inline int MyMPI_GetId (MPI_Comm comm = ng_comm)
+  inline int MyMPI_GetId (MPI_Comm comm /* = ng_comm */)
   {
     int id;
     MPI_Comm_rank(comm, &id);
@@ -40,10 +41,11 @@ namespace netgen
   }
 #else
   // enum { MPI_COMM_WORLD = 12345, MPI_COMM_NULL = 0};
-  inline int MyMPI_GetNTasks (MPI_Comm comm = ng_comm) { return 1; }
-  inline int MyMPI_GetId (MPI_Comm comm = ng_comm) { return 0; }
+  inline int MyMPI_GetNTasks (MPI_Comm comm /* = ng_comm */) { return 1; }
+  inline int MyMPI_GetId (MPI_Comm comm /* = ng_comm */) { return 0; }
 #endif
-
+#endif
+  
   /*
 #ifdef PARALLEL
   // For python wrapping of communicators
@@ -112,13 +114,13 @@ namespace netgen
   enum { MPI_TAG_MESH = 210 };
   enum { MPI_TAG_VIS = 310 };
 
-  inline void MyMPI_Send (int i, int dest, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Send (int i, int dest, int tag, MPI_Comm comm /* = ng_comm */)
   {
     int hi = i;
     MPI_Send( &hi, 1, MPI_INT, dest, tag, comm);
   }
 
-  inline void MyMPI_Recv (int & i, int src, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Recv (int & i, int src, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Status status;
     MPI_Recv( &i, 1, MPI_INT, src, tag, comm, &status);
@@ -126,12 +128,12 @@ namespace netgen
 
 
 
-  inline void MyMPI_Send (const string & s, int dest, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Send (const string & s, int dest, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Send( const_cast<char*> (s.c_str()), s.length(), MPI_CHAR, dest, tag, comm);
   }
 
-  inline void MyMPI_Recv (string & s, int src, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Recv (string & s, int src, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Status status;
     int len;
@@ -145,20 +147,20 @@ namespace netgen
 
 
   template <class T, int BASE>
-  inline void MyMPI_Send (FlatArray<T, BASE> s, int dest, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Send (FlatArray<T, BASE> s, int dest, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Send( &s.First(), s.Size(), MyGetMPIType<T>(), dest, tag, comm);
   }
 
   template <class T, int BASE>
-  inline void MyMPI_Recv ( FlatArray<T, BASE> s, int src, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Recv ( FlatArray<T, BASE> s, int src, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Status status;
     MPI_Recv( &s.First(), s.Size(), MyGetMPIType<T>(), src, tag, comm, &status);
   }
 
   template <class T, int BASE>
-  inline void MyMPI_Recv ( Array <T, BASE> & s, int src, int tag, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Recv ( Array <T, BASE> & s, int src, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Status status;
     int len;
@@ -170,7 +172,7 @@ namespace netgen
   }
 
   template <class T, int BASE>
-  inline int MyMPI_Recv ( Array <T, BASE> & s, int tag, MPI_Comm comm = ng_comm)
+  inline int MyMPI_Recv ( Array <T, BASE> & s, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Status status;
     int len;
@@ -203,7 +205,7 @@ namespace netgen
   */
 
   template <class T, int BASE>
-  inline MPI_Request MyMPI_ISend (FlatArray<T, BASE> s, int dest, int tag, MPI_Comm comm = ng_comm)
+  inline MPI_Request MyMPI_ISend (FlatArray<T, BASE> s, int dest, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Request request;
     MPI_Isend( &s.First(), s.Size(), MyGetMPIType<T>(), dest, tag, comm, &request);
@@ -212,7 +214,7 @@ namespace netgen
 
 
   template <class T, int BASE>
-  inline MPI_Request MyMPI_IRecv (FlatArray<T, BASE> s, int dest, int tag, MPI_Comm comm = ng_comm)
+  inline MPI_Request MyMPI_IRecv (FlatArray<T, BASE> s, int dest, int tag, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Request request;
     MPI_Irecv( &s.First(), s.Size(), MyGetMPIType<T>(), dest, tag, comm, &request);
@@ -277,11 +279,15 @@ namespace netgen
   template <typename T>
   inline void MyMPI_ExchangeTable (TABLE<T> & send_data, 
 				   TABLE<T> & recv_data, int tag,
-				   MPI_Comm comm = ng_comm)
+				   const NgMPI_Comm & comm /* = ng_comm */)
   {
+    /*
     int rank = MyMPI_GetId(comm);
     int ntasks = MyMPI_GetNTasks(comm);
-
+    */
+    int rank = comm.Rank();
+    int ntasks = comm.Size();
+    
     Array<int> send_sizes(ntasks);
     Array<int> recv_sizes(ntasks);
     for (int i = 0; i < ntasks; i++)
@@ -324,22 +330,23 @@ namespace netgen
 
 
   template <class T>
-  inline void MyMPI_Bcast (T & s, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Bcast (T & s, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Bcast (&s, 1, MyGetMPIType<T>(), 0, comm);
   }
 
   template <class T>
-  inline void MyMPI_Bcast (Array<T, 0> & s, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Bcast (Array<T, 0> & s, NgMPI_Comm comm /* = ng_comm */)
   {
     int size = s.Size();
     MyMPI_Bcast (size, comm);
-    if (MyMPI_GetId(comm) != 0) s.SetSize (size);
+    // if (MyMPI_GetId(comm) != 0) s.SetSize (size);
+    if (comm.Rank() != 0) s.SetSize (size);
     MPI_Bcast (&s[0], size, MyGetMPIType<T>(), 0, comm);
   }
 
   template <class T>
-  inline void MyMPI_Bcast (Array<T, 0> & s, int root, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Bcast (Array<T, 0> & s, int root, MPI_Comm comm /* = ng_comm */)
   {
     int id;
     MPI_Comm_rank(comm, &id);
@@ -352,13 +359,13 @@ namespace netgen
   }
 
   template <class T, class T2>
-  inline void MyMPI_Allgather (const T & send, FlatArray<T2> recv, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Allgather (const T & send, FlatArray<T2> recv, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Allgather( const_cast<T*> (&send), 1, MyGetMPIType<T>(), &recv[0], 1, MyGetMPIType<T2>(), comm);
   }
 
   template <class T, class T2>
-  inline void MyMPI_Alltoall (FlatArray<T> send, FlatArray<T2> recv, MPI_Comm comm = ng_comm)
+  inline void MyMPI_Alltoall (FlatArray<T> send, FlatArray<T2> recv, MPI_Comm comm /* = ng_comm */)
   {
     MPI_Alltoall( &send[0], 1, MyGetMPIType<T>(), &recv[0], 1, MyGetMPIType<T2>(), comm);
   }
diff --git a/libsrc/include/nginterface.h b/libsrc/include/nginterface.h
index 70d440d8..6c0cd284 100644
--- a/libsrc/include/nginterface.h
+++ b/libsrc/include/nginterface.h
@@ -40,7 +40,7 @@
 // #ifndef PARALLEL
 // typedef int MPI_Comm;
 // #endif
-namespace netgen { extern DLL_HEADER ngcore::NgMPI_Comm ng_comm; }
+// namespace netgen { extern DLL_HEADER ngcore::NgMPI_Comm ng_comm; }
 
 
 // implemented element types:
@@ -66,7 +66,7 @@ extern "C" {
   DLL_HEADER void Ng_LoadGeometry (const char * filename);
 
   // load netgen mesh
-  DLL_HEADER void Ng_LoadMesh (const char * filename, ngcore::NgMPI_Comm comm = netgen::ng_comm);
+  DLL_HEADER void Ng_LoadMesh (const char * filename, ngcore::NgMPI_Comm comm = ngcore::NgMPI_Comm{});
 
   // load netgen mesh
   DLL_HEADER void Ng_LoadMeshFromString (const char * mesh_as_string);
diff --git a/libsrc/include/nginterface_v2.hpp b/libsrc/include/nginterface_v2.hpp
index 6d1eb0b5..24b9b3e9 100644
--- a/libsrc/include/nginterface_v2.hpp
+++ b/libsrc/include/nginterface_v2.hpp
@@ -36,7 +36,7 @@ namespace netgen
   using namespace std;
   using namespace ngcore;
   
-  extern DLL_HEADER NgMPI_Comm ng_comm;
+  // extern DLL_HEADER NgMPI_Comm ng_comm;
   
   static constexpr int POINTINDEX_BASE = 1;
   
@@ -265,11 +265,11 @@ namespace netgen
     /** reuse a netgen-mesh **/
     Ngx_Mesh (shared_ptr<Mesh> amesh); 
     /** load a new mesh **/
-    Ngx_Mesh (string filename, MPI_Comm acomm = netgen::ng_comm);
+    Ngx_Mesh (string filename, NgMPI_Comm acomm = NgMPI_Comm{});
     
-    void LoadMesh (const string & filename, MPI_Comm comm = netgen::ng_comm);
+    void LoadMesh (const string & filename, NgMPI_Comm comm = NgMPI_Comm{});
 
-    void LoadMesh (istream & str, MPI_Comm comm = netgen::ng_comm);
+    void LoadMesh (istream & str, NgMPI_Comm comm = NgMPI_Comm{});
     void SaveMesh (ostream & str) const;
     void UpdateTopology ();
     void DoArchive (Archive & archive);
diff --git a/libsrc/interface/nginterface.cpp b/libsrc/interface/nginterface.cpp
index 8abaa026..e23d2bf5 100644
--- a/libsrc/interface/nginterface.cpp
+++ b/libsrc/interface/nginterface.cpp
@@ -119,8 +119,8 @@ void Ng_LoadMeshFromStream ( istream & input )
 
 void Ng_LoadMesh (const char * filename, ngcore::NgMPI_Comm comm)
 {
-  int id = MyMPI_GetId(comm);
-  int ntasks = MyMPI_GetNTasks(comm);
+  int id = comm.Rank();
+  int ntasks = comm.Size();
 
   {
     ifstream infile(filename);
diff --git a/libsrc/interface/nginterface_v2.cpp b/libsrc/interface/nginterface_v2.cpp
index e68393f1..5da74e58 100644
--- a/libsrc/interface/nginterface_v2.cpp
+++ b/libsrc/interface/nginterface_v2.cpp
@@ -33,17 +33,17 @@ namespace netgen
   
   Ngx_Mesh :: Ngx_Mesh (shared_ptr<Mesh> amesh)
   { mesh = amesh ? amesh : netgen::mesh; }
-  Ngx_Mesh :: Ngx_Mesh (string filename, MPI_Comm acomm)
+  Ngx_Mesh :: Ngx_Mesh (string filename, NgMPI_Comm acomm)
   { LoadMesh(filename, acomm); }
   
-  Ngx_Mesh * LoadMesh (const string & filename, MPI_Comm comm = netgen::ng_comm)
+  Ngx_Mesh * LoadMesh (const string & filename, NgMPI_Comm comm)
   {
     netgen::mesh.reset();
     Ng_LoadMesh (filename.c_str(), comm);
     return new Ngx_Mesh (netgen::mesh);
   }
 
-  void Ngx_Mesh :: LoadMesh (const string & filename, MPI_Comm comm)
+  void Ngx_Mesh :: LoadMesh (const string & filename, NgMPI_Comm comm)
   {
     netgen::mesh.reset();
     Ng_LoadMesh (filename.c_str(), comm);
@@ -51,7 +51,7 @@ namespace netgen
     mesh = netgen::mesh;
   }
 
-  void Ngx_Mesh :: LoadMesh (istream & ist, MPI_Comm comm)
+  void Ngx_Mesh :: LoadMesh (istream & ist, NgMPI_Comm comm)
   {
     netgen::mesh = make_shared<Mesh>();
     netgen::mesh->SetCommunicator(comm);
diff --git a/libsrc/meshing/curvedelems.cpp b/libsrc/meshing/curvedelems.cpp
index 182945d3..e694968c 100644
--- a/libsrc/meshing/curvedelems.cpp
+++ b/libsrc/meshing/curvedelems.cpp
@@ -553,18 +553,19 @@ namespace netgen
     order = 1;
 
 
-    MPI_Comm curve_comm;
+    // MPI_Comm curve_comm;
+    const auto & curve_comm = mesh.GetCommunicator();
 #ifdef PARALLEL
     enum { MPI_TAG_CURVE = MPI_TAG_MESH+20 };
 
     const ParallelMeshTopology & partop = mesh.GetParallelTopology ();
-    MPI_Comm_dup (mesh.GetCommunicator(), &curve_comm);      
+    // MPI_Comm_dup (mesh.GetCommunicator(), &curve_comm);      
     Array<int> procs;
 #else
-    curve_comm = ng_comm; // dummy! 
+    // curve_comm = mesh.GetCommunicator();
 #endif
-    int rank = MyMPI_GetId(curve_comm);
-    int ntasks = MyMPI_GetNTasks(curve_comm);
+    int rank = curve_comm.Rank();
+    int ntasks = curve_comm.Size();
 
     if (working)
       order = aorder;
@@ -656,8 +657,8 @@ namespace netgen
 	  }
       }
 
-    
-    MyMPI_ExchangeTable (send_orders, recv_orders, MPI_TAG_CURVE, curve_comm);
+    if (ntasks > 1)
+      MyMPI_ExchangeTable (send_orders, recv_orders, MPI_TAG_CURVE, curve_comm);
 
     if (ntasks > 1 && working)
       {
@@ -1186,7 +1187,8 @@ namespace netgen
 	  }
       }
 
-    MyMPI_ExchangeTable (send_surfnr, recv_surfnr, MPI_TAG_CURVE, curve_comm);
+    if (ntasks > 1)
+      MyMPI_ExchangeTable (send_surfnr, recv_surfnr, MPI_TAG_CURVE, curve_comm);
 
     if (ntasks > 1 && working)
       {
@@ -1369,8 +1371,8 @@ namespace netgen
 
 
 #ifdef PARALLEL
-    MPI_Barrier (curve_comm);
-    MPI_Comm_free (&curve_comm);      
+    curve_comm.Barrier();
+    // MPI_Comm_free (&curve_comm);      
 #endif
   }
 
diff --git a/libsrc/meshing/global.cpp b/libsrc/meshing/global.cpp
index 3b2a1c5f..18092496 100644
--- a/libsrc/meshing/global.cpp
+++ b/libsrc/meshing/global.cpp
@@ -32,7 +32,7 @@ namespace netgen
   // TraceGlobal glob2("global2");
 
   // global communicator for netgen
-  DLL_HEADER NgMPI_Comm ng_comm;
+  // DLL_HEADER NgMPI_Comm ng_comm;
   
   weak_ptr<Mesh> global_mesh;
   void SetGlobalMesh (shared_ptr<Mesh> m)
diff --git a/libsrc/meshing/global.hpp b/libsrc/meshing/global.hpp
index aa7f7cd2..b1da9344 100644
--- a/libsrc/meshing/global.hpp
+++ b/libsrc/meshing/global.hpp
@@ -61,7 +61,7 @@ namespace netgen
   DLL_HEADER void SetGlobalMesh (shared_ptr<Mesh> m);
 
   // global communicator for netgen (dummy if no MPI)
-  extern DLL_HEADER NgMPI_Comm ng_comm;
+  // extern DLL_HEADER NgMPI_Comm ng_comm;
   
 }
 
diff --git a/libsrc/meshing/meshclass.cpp b/libsrc/meshing/meshclass.cpp
index eeda22da..5ed9663e 100644
--- a/libsrc/meshing/meshclass.cpp
+++ b/libsrc/meshing/meshclass.cpp
@@ -43,7 +43,7 @@ namespace netgen
     bcnames.SetSize(0);
     cd2names.SetSize(0);
 
-    this->comm = netgen :: ng_comm;
+    // this->comm = netgen :: ng_comm;
 #ifdef PARALLEL
     paralleltop = new ParallelMeshTopology (*this);
 #endif
@@ -1325,8 +1325,8 @@ namespace netgen
     
     if (archive.Input())
       {
-	int rank = MyMPI_GetId(GetCommunicator());
-	int ntasks = MyMPI_GetNTasks(GetCommunicator());
+	int rank = GetCommunicator().Rank();
+	int ntasks = GetCommunicator().Size();
 	
         RebuildSurfaceElementLists();
         
diff --git a/libsrc/meshing/parallelmesh.cpp b/libsrc/meshing/parallelmesh.cpp
index e9c040ef..0eed1dfe 100644
--- a/libsrc/meshing/parallelmesh.cpp
+++ b/libsrc/meshing/parallelmesh.cpp
@@ -35,8 +35,8 @@ namespace netgen
 
   void Mesh :: SendRecvMesh ()
   {
-    int id = MyMPI_GetId(GetCommunicator());
-    int np = MyMPI_GetNTasks(GetCommunicator());
+    int id = GetCommunicator().Rank();
+    int np = GetCommunicator().Size();
 
     if (np == 1) {
       throw NgException("SendRecvMesh called, but only one rank in communicator!!");
@@ -72,9 +72,9 @@ namespace netgen
   {
     Array<MPI_Request> sendrequests;
 
-    MPI_Comm comm = GetCommunicator();
-    int id = MyMPI_GetId(comm);
-    int ntasks = MyMPI_GetNTasks(comm);
+    NgMPI_Comm comm = GetCommunicator();
+    int id = comm.Rank();
+    int ntasks = comm.Size();
 
     int dim = GetDimension();
     MyMPI_Bcast(dim, comm);
@@ -751,8 +751,9 @@ namespace netgen
     int timer_sels = NgProfiler::CreateTimer ("Receive surface elements");
     NgProfiler::RegionTimer reg(timer);
 
-    int id = MyMPI_GetId(GetCommunicator());
-    int ntasks = MyMPI_GetNTasks(GetCommunicator());
+    NgMPI_Comm comm = GetCommunicator();
+    int id = comm.Rank();
+    int ntasks = comm.Size();
     
     int dim;
     MyMPI_Bcast(dim, comm);
@@ -1011,9 +1012,9 @@ namespace netgen
   // call it only for the master !
   void Mesh :: Distribute ()
   {
-    MPI_Comm comm = GetCommunicator();
-    int id = MyMPI_GetId(comm);
-    int ntasks = MyMPI_GetNTasks(comm);
+    NgMPI_Comm comm = GetCommunicator();
+    int id = comm.Rank();
+    int ntasks = comm.Size();
 
     if (id != 0 || ntasks == 1 ) return;
 
@@ -1072,7 +1073,7 @@ namespace netgen
     eptr.Append (eind.Size());
     Array<idx_t> epart(ne), npart(nn);
 
-    idxtype nparts = MyMPI_GetNTasks(GetCommunicator())-1;
+    idxtype nparts = GetCommunicator().Size()-1;
 
     if (nparts == 1)
       {
@@ -1293,9 +1294,9 @@ namespace netgen
   // call it only for the master !
   void Mesh :: Distribute (Array<int> & volume_weights , Array<int>  & surface_weights, Array<int>  & segment_weights)
   {
-    MPI_Comm comm = GetCommunicator();
-    int id = MyMPI_GetId(comm);
-    int ntasks = MyMPI_GetNTasks(comm);
+    NgMPI_Comm comm = GetCommunicator();
+    int id = comm.Rank();
+    int ntasks = comm.Size();
 
     if (id != 0 || ntasks == 1 ) return;
 
@@ -1385,7 +1386,7 @@ namespace netgen
     eptr.Append (eind.Size());
     Array<idx_t> epart(ne), npart(nn);
 
-    idxtype nparts = MyMPI_GetNTasks(GetCommunicator())-1;
+    idxtype nparts = GetCommunicator().Size()-1;
 
     if (nparts == 1)
       {
diff --git a/libsrc/meshing/paralleltop.cpp b/libsrc/meshing/paralleltop.cpp
index 346b5e25..997d5465 100644
--- a/libsrc/meshing/paralleltop.cpp
+++ b/libsrc/meshing/paralleltop.cpp
@@ -25,8 +25,9 @@ namespace netgen
   {
     *testout << "ParallelMeshTopology::Reset" << endl;
 
-    int id = MyMPI_GetId(mesh.GetCommunicator());
-    int ntasks = MyMPI_GetNTasks(mesh.GetCommunicator());
+    NgMPI_Comm comm = mesh.GetCommunicator();
+    int id = comm.Rank();
+    int ntasks = comm.Size();
     
     if ( ntasks == 1 ) return;
 
@@ -125,7 +126,8 @@ namespace netgen
     *testout << "ParallelMeshTopology :: UpdateCoarseGridGlobal" << endl;
 
     const MeshTopology & topology = mesh.GetTopology();
-
+    MPI_Comm comm = mesh.GetCommunicator();
+    
     if ( id == 0 )
       {
 	Array<Array<int>*> sendarrays(ntasks);
@@ -160,7 +162,7 @@ namespace netgen
 
 	Array<MPI_Request> sendrequests;
 	for (int dest = 1; dest < ntasks; dest++)
-	  sendrequests.Append (MyMPI_ISend (*sendarrays[dest], dest, MPI_TAG_MESH+10));
+	  sendrequests.Append (MyMPI_ISend (*sendarrays[dest], dest, MPI_TAG_MESH+10, comm));
 	MPI_Waitall (sendrequests.Size(), &sendrequests[0], MPI_STATUS_IGNORE);
 
 	for (int dest = 1; dest < ntasks; dest++)
@@ -171,7 +173,7 @@ namespace netgen
 
       {
 	Array<int> recvarray;
-	MyMPI_Recv (recvarray, 0, MPI_TAG_MESH+10);
+	MyMPI_Recv (recvarray, 0, MPI_TAG_MESH+10, comm);
 
 	int ii = 0;
 
@@ -209,10 +211,12 @@ namespace netgen
     // cout << "UpdateCoarseGrid" << endl;
     // if (is_updated) return;
 
-    MPI_Comm comm = mesh.GetCommunicator();
-    int id = MyMPI_GetId(comm);
-    int ntasks = MyMPI_GetNTasks(comm);
+    NgMPI_Comm comm = mesh.GetCommunicator();
+    int id = comm.Rank();
+    int ntasks = comm.Size();
 
+    if (ntasks == 1) return;
+    
     Reset();
     static int timer = NgProfiler::CreateTimer ("UpdateCoarseGrid");
     NgProfiler::RegionTimer reg(timer);
diff --git a/libsrc/meshing/python_mesh.cpp b/libsrc/meshing/python_mesh.cpp
index 3c15e3bd..bfc02341 100644
--- a/libsrc/meshing/python_mesh.cpp
+++ b/libsrc/meshing/python_mesh.cpp
@@ -20,7 +20,7 @@ namespace netgen
 #ifdef PARALLEL
   /** we need allreduce in python-wrapped communicators **/
   template <typename T>
-  inline T MyMPI_AllReduceNG (T d, const MPI_Op & op = MPI_SUM, MPI_Comm comm = ng_comm)
+  inline T MyMPI_AllReduceNG (T d, const MPI_Op & op /* = MPI_SUM */, MPI_Comm comm)
   {
     T global_d;
     MPI_Allreduce ( &d, &global_d, 1, MyGetMPIType<T>(), op, comm);
@@ -30,7 +30,7 @@ namespace netgen
   enum { MPI_SUM = 0, MPI_MIN = 1, MPI_MAX = 2 };
   typedef int MPI_Op;
   template <typename T>
-  inline T MyMPI_AllReduceNG (T d, const MPI_Op & op = MPI_SUM, MPI_Comm comm = ng_comm)
+  inline T MyMPI_AllReduceNG (T d, const MPI_Op & op /* = MPI_SUM */, MPI_Comm comm)
   { return d; }
 #endif
 }
@@ -89,12 +89,11 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
   py::class_<NgMPI_Comm> (m, "MPI_Comm")
     .def_property_readonly ("rank", &NgMPI_Comm::Rank)
     .def_property_readonly ("size", &NgMPI_Comm::Size)
-
+    .def("Barrier", &NgMPI_Comm::Barrier)
+    
 #ifdef PARALLEL
-    .def("Barrier", [](NgMPI_Comm & c) { MPI_Barrier(c); })
     .def("WTime", [](NgMPI_Comm  & c) { return MPI_Wtime(); })
 #else
-    .def("Barrier", [](NgMPI_Comm & c) { })
     .def("WTime", [](NgMPI_Comm  & c) { return -1.0; })
 #endif
     .def("Sum", [](NgMPI_Comm  & c, double x) { return MyMPI_AllReduceNG(x, MPI_SUM, c); })
@@ -557,13 +556,13 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
     .def_property_readonly("_timestamp", &Mesh::GetTimeStamp)
     .def("Distribute", [](shared_ptr<Mesh> self, NgMPI_Comm comm) {
 	self->SetCommunicator(comm);
-	if(MyMPI_GetNTasks(comm)==1) return self;
+	if(comm.Size()==1) return self;
 	// if(MyMPI_GetNTasks(comm)==2) throw NgException("Sorry, cannot handle communicators with NP=2!");
 	// cout << " rank " << MyMPI_GetId(comm) << " of " << MyMPI_GetNTasks(comm) << " called Distribute " << endl;
-	if(MyMPI_GetId(comm)==0) self->Distribute();
+	if(comm.Rank()==0) self->Distribute();
 	else self->SendRecvMesh();
         return self;
-      }, py::arg("comm")=NgMPI_Comm(ng_comm))
+      }, py::arg("comm"))
     .def("Receive", [](NgMPI_Comm comm) {
         auto mesh = make_shared<Mesh>();
         mesh->SetCommunicator(comm);
@@ -575,9 +574,9 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
 	  {
 	    istream * infile;
 
-	    MPI_Comm comm = self.GetCommunicator();
-	    id = MyMPI_GetId(comm);
-	    ntasks = MyMPI_GetNTasks(comm);
+	    NgMPI_Comm comm = self.GetCommunicator();
+	    id = comm.Rank();
+	    ntasks = comm.Size();
 
 #ifdef PARALLEL
 	    char* buf = nullptr;
diff --git a/libsrc/visualization/vssolution.cpp b/libsrc/visualization/vssolution.cpp
index 3b0b61cc..6e758687 100644
--- a/libsrc/visualization/vssolution.cpp
+++ b/libsrc/visualization/vssolution.cpp
@@ -2650,13 +2650,17 @@ namespace netgen
     static int timer2 = NgProfiler::CreateTimer ("getminmax, surf");
 
 #ifdef PARALLEL
-    if (id == 0)
+    auto comm = mesh->GetCommunicator();
+    if (comm.Size() > 1)
       {
-	MyMPI_SendCmd ("redraw");
-	MyMPI_SendCmd ("getminmax");
+        if (id == 0)
+          {
+            MyMPI_SendCmd ("redraw");
+            MyMPI_SendCmd ("getminmax");
+          }
+        MyMPI_Bcast (funcnr, mesh->GetCommunicator());
+        MyMPI_Bcast (comp, mesh->GetCommunicator());
       }
-    MyMPI_Bcast (funcnr);
-    MyMPI_Bcast (comp);
 #endif
 
     // double val;
@@ -2744,11 +2748,14 @@ namespace netgen
 	minv = 1e99;
 	maxv = -1e99;
       }
-    double hmin, hmax;
-    MPI_Reduce (&minv, &hmin, 1, MPI_DOUBLE, MPI_MIN, 0, MPI_COMM_WORLD);
-    MPI_Reduce (&maxv, &hmax, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
-    minv = hmin;
-    maxv = hmax;
+    if (ntasks > 1)
+      {
+        double hmin, hmax;
+        MPI_Reduce (&minv, &hmin, 1, MPI_DOUBLE, MPI_MIN, 0, MPI_COMM_WORLD);
+        MPI_Reduce (&maxv, &hmax, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
+        minv = hmin;
+        maxv = hmax;
+      }
 #endif
   }
 
diff --git a/ng/ngappinit.cpp b/ng/ngappinit.cpp
index 8c90d069..a3db7789 100644
--- a/ng/ngappinit.cpp
+++ b/ng/ngappinit.cpp
@@ -77,7 +77,7 @@ int main(int argc, char ** argv)
       throw ngcore::Exception("Netgen GUI cannot run MPI-parallel");
 
   // MPI_COMM_WORLD is just a local communicator
-  netgen::ng_comm = ngcore::NgMPI_Comm{MPI_COMM_WORLD, false};
+  // netgen::ng_comm = ngcore::NgMPI_Comm{MPI_COMM_WORLD, false};
 
 #endif
 
diff --git a/ng/ngpkg.cpp b/ng/ngpkg.cpp
index 5b67637a..bc047495 100644
--- a/ng/ngpkg.cpp
+++ b/ng/ngpkg.cpp
@@ -1219,7 +1219,7 @@ namespace netgen
 
 #ifdef PARALLEL
     MyMPI_SendCmd ("bcastparthread");
-    MyMPI_Bcast (mparam.parthread);
+    MyMPI_Bcast (mparam.parthread, MPI_COMM_WORLD);
 #endif
 
     return TCL_OK;
diff --git a/ng/parallelfunc.cpp b/ng/parallelfunc.cpp
index ac95b226..6c7498ac 100644
--- a/ng/parallelfunc.cpp
+++ b/ng/parallelfunc.cpp
@@ -125,7 +125,7 @@ void ParallelRun()
       
       else if ( message == "bcastparthread" )
 	{
-	  MyMPI_Bcast (mparam.parthread);
+	  MyMPI_Bcast (mparam.parthread, MPI_COMM_WORLD);
 	}