diff --git a/src/cimrsprotocol.cpp b/src/cimrsprotocol.cpp
index 4ad5fe3..7d7fa2b 100644
--- a/src/cimrsprotocol.cpp
+++ b/src/cimrsprotocol.cpp
@@ -55,6 +55,11 @@ bool CImrsProtocol::Init(void)
     // update time
     m_LastKeepaliveTime.Now();
     
+    // random number generator
+    std::random_device rd;
+    std::mt19937 mt(rd());
+    m_Random = mt;
+
     // done
     return ok;
 }
@@ -76,9 +81,10 @@ void CImrsProtocol::Task(void)
     //CYSFFICH            Fich;
     CDvHeaderPacket     *Header;
     CDvFramePacket      *Frames[5];
+    int sno;
 
     // handle incoming packets
-    if ( m_Socket.Receive(&Buffer, &Ip, 20) != -1 )
+    if ( m_Socket.Receive(&Buffer, &Ip, 20, &sno) != -1 )
     {
         // force port
         Ip.SetPort(IMRS_PORT);
@@ -123,7 +129,7 @@ void CImrsProtocol::Task(void)
             //std::cout << "IMRS ping packet from "  << Ip << std::endl;
             
             // acknowledge request
-            EncodePongPacket(&Buffer);
+            EncodePongPacket(&Buffer, sno);
             m_Socket.Send(Buffer, Ip, IMRS_PORT);
 
             // and our turn
@@ -404,7 +410,7 @@ bool CImrsProtocol::IsValidDvHeaderPacket(const CIp &Ip, const CBuffer &Buffer,
     if ( (Buffer.size() == 91) && (Buffer.at(1) == 0x4B) )
     {
         // get stream id
-        uint32 uiStreamId = IpToStreamId(Ip);
+        uint32 uiStreamId = CreateStreamId();
         
         // and payload
         CBuffer payload;
@@ -483,7 +489,7 @@ bool CImrsProtocol::IsValidDvFramePacket(const CIp &Ip, const CBuffer &Buffer, C
     if ( (Buffer.size() == 181) && (Buffer.at(1) == 0xA5) )
     {
         // get stream id
-        uint32 uiStreamId = IpToStreamId(Ip);
+        uint32 uiStreamId = CreateStreamId();
 
         // and payload
         CBuffer payload;
@@ -576,7 +582,7 @@ bool CImrsProtocol::IsValidDvLastFramePacket(const CIp &Ip, const CBuffer &Buffe
     if ( (Buffer.size() == 31) && (Buffer.at(1) == 0x0F) )
     {
         // get stream id
-        uint32 uiStreamId = IpToStreamId(Ip);
+        uint32 uiStreamId = CreateStreamId();
         
         // and payload
         CBuffer payload;
@@ -639,7 +645,7 @@ void CImrsProtocol::EncodePingPacket(CBuffer *Buffer) const
     Buffer->Set(tag, sizeof(tag));
 }
 
-void CImrsProtocol::EncodePongPacket(CBuffer *Buffer) const
+void CImrsProtocol::EncodePongPacket(CBuffer *Buffer, int sno) const
 {
     uint8 tag1[] = { 0x00,0x2C,0x08,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x04,0x00,0x00 };
     uint8 radioid[] = { 'G','0','g','B','J' };
@@ -648,7 +654,7 @@ void CImrsProtocol::EncodePongPacket(CBuffer *Buffer) const
     // tag
     Buffer->Set(tag1, sizeof(tag1));
     // mac address
-    Buffer->Append(g_Reflector.GetListenMac(), 6);
+    Buffer->Append(g_Reflector.GetListenMac(sno), 6);
     // callsign
     ::memset(sz, ' ', sizeof(sz));
     g_Reflector.GetCallsign().GetCallsignString(sz);
@@ -894,9 +900,9 @@ bool CImrsProtocol::EncodeDvLastPacket(const CDvHeaderPacket &Header, const CDvL
 ////////////////////////////////////////////////////////////////////////////////////////
 // uiStreamId helpers
 
-uint32 CImrsProtocol::IpToStreamId(const CIp &ip) const
+uint32 CImrsProtocol::CreateStreamId(void) const
 {
-    return ip.GetAddr() ^ (uint32)(MAKEDWORD(ip.GetPort(), ip.GetPort()));
+    return m_Random();
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/cimrsprotocol.h b/src/cimrsprotocol.h
index 62e024d..eb02e1f 100644
--- a/src/cimrsprotocol.h
+++ b/src/cimrsprotocol.h
@@ -93,13 +93,13 @@ protected:
     
     // DV packet encoding helpers
     void EncodePingPacket(CBuffer *) const;
-    void EncodePongPacket(CBuffer *) const;
+    void EncodePongPacket(CBuffer *, int) const;
     bool EncodeDvHeaderPacket(const CDvHeaderPacket &, CBuffer *) const;
     bool EncodeDvPacket(const CDvHeaderPacket &, const CDvFramePacket *, CBuffer *) const;
     bool EncodeDvLastPacket(const CDvHeaderPacket &, const CDvLastFramePacket &, CBuffer *) const;
 
     // uiStreamId helpers
-    uint32 IpToStreamId(const CIp &) const;
+    uint32 CreateStreamId(void) const;
     
     // DG-ID helper
     char DgidToModule(uint8 uiDgid) const;
@@ -111,6 +111,9 @@ protected:
     
     // for queue header caches
     std::array<CImrsStreamCacheItem, NB_OF_MODULES>    m_StreamsCache;
+
+    // random number generator
+    mutable std::mt19937        m_Random;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/creflector.h b/src/creflector.h
index 354ec3d..ea2967e 100644
--- a/src/creflector.h
+++ b/src/creflector.h
@@ -61,7 +61,7 @@ public:
     void SetListenIp(int i, const CIp &ip)          { m_Ip[i] = ip; UpdateListenMac(i); }
     void SetTranscoderIp(const CIp &ip)             { m_AmbedIp = ip; }
     const CIp &GetListenIp(int i = 0) const         { return m_Ip[i]; }
-    const uint8 *GetListenMac(int i = 0) const      { return (const uint8 *)m_Mac[i]; }
+    const uint8 *GetListenMac(int i) const          { return (const uint8 *)m_Mac[i]; }
     const CIp &GetTranscoderIp(void) const          { return m_AmbedIp; }
     
     // operation
diff --git a/src/cudpsocket.cpp b/src/cudpsocket.cpp
index 4499c86..f1b6e03 100644
--- a/src/cudpsocket.cpp
+++ b/src/cudpsocket.cpp
@@ -123,12 +123,13 @@ int CUdpSocket::GetSocket(const CIp &Ip)
 ////////////////////////////////////////////////////////////////////////////////////////
 // read
 
-int CUdpSocket::Receive(CBuffer *Buffer, CIp *Ip, int timeout)
+int CUdpSocket::Receive(CBuffer *Buffer, CIp *Ip, int timeout, int *sno)
 {
     struct sockaddr_storage Sin;
     struct pollfd pfd[UDP_SOCKET_MAX];
     socklen_t uiFromLen = sizeof(Sin);
     int i, socks, index, iRecvLen = -1;
+    int index2sno[UDP_SOCKET_MAX];
     
     // socket valid ?
     for ( i = socks = 0; i < UDP_SOCKET_MAX; i++ )
@@ -137,6 +138,7 @@ int CUdpSocket::Receive(CBuffer *Buffer, CIp *Ip, int timeout)
         {
             pfd[socks].fd = m_Socket[i];
             pfd[socks].events = POLLIN;
+            index2sno[socks] = i;
             socks++;
         }
     }
@@ -170,6 +172,12 @@ int CUdpSocket::Receive(CBuffer *Buffer, CIp *Ip, int timeout)
                     // get IP
                     Ip->SetSockAddr(&Sin, uiFromLen);
                     
+                    // record the number of incoming socket
+                    if ( sno != NULL )
+                    {                    
+                        *sno = index2sno[index];
+                    }
+
                     m_Counter++;
                     break;
                 }
diff --git a/src/cudpsocket.h b/src/cudpsocket.h
index ae8418c..7d5b40f 100644
--- a/src/cudpsocket.h
+++ b/src/cudpsocket.h
@@ -62,7 +62,7 @@ public:
     int  GetSocket(const CIp &);
     
     // read
-    int Receive(CBuffer *, CIp *, int);
+    int Receive(CBuffer *, CIp *, int, int * = NULL);
     
     // write
     int Send(const CBuffer &, const CIp &);