#include <ns3/inet-socket-address.h>

#include <ns3/mac48-address.h>

#include <ns3/epc-gtpu-tunnel-endpoint.h>

#include <ns3/eps-bearer.h>

#include <ns3/ipv4-address.h>

#include <ns3/internet-stack-helper.h>

#include <ns3/point-to-point-helper.h>

#include <ns3/packet-socket-helper.h>

#include <ns3/packet-socket-address.h>

#include <ns3/epc-enb-application.h>

#include <ns3/epc-sgw-pgw-application.h>

  : m_gtpuUdpPort (2152) // fixed by the standard

  m_s1uIpv4AddressHelper.SetBase ("10.0.0.0", "255.255.255.252");

  // we use a /8 net for all UEs

  m_ueAddressHelper.SetBase ("7.0.0.0", "255.0.0.0");

  InternetStackHelper internet;

  internet.Install (m_sgwPgw);

  // create S1-U socket

  int retval = sgwPgwS1uSocket->Bind (InetSocketAddress (Ipv4Address::GetAny (), m_gtpuUdpPort));

  NS_ASSERT (retval == 0);

  // create TUN device implementing tunneling of user data over GTP-U/UDP/IP 

  Ptr<VirtualNetDevice> giTunDevice = CreateObject<VirtualNetDevice> ();

  // yes we need this

  giTunDevice->SetAddress (Mac48Address::Allocate ()); 

  m_sgwPgw->AddDevice (giTunDevice);

  NetDeviceContainer giTunDeviceContainer;

  giTunDeviceContainer.Add (giTunDevice);

  // the TUN device is on the same subnet as the UEs, so when a packet

  // addressed to an UE arrives at the intenet to the WAN interface of

  // the PGW it will be forwarded to the TUN device. 

  Ipv4InterfaceContainer giTunDeviceIpv4IfContainer = m_ueAddressHelper.Assign (giTunDeviceContainer);  

  // create EpcSgwPgwApplication

  m_sgwPgwApp = CreateObject<EpcSgwPgwApplication> (giTunDevice, sgwPgwS1uSocket);

  m_sgwPgw->AddApplication (m_sgwPgwApp);

  // connect SgwPgwApplication and virtual net device for tunneling

  giTunDevice->SetSendCallback (MakeCallback (&EpcSgwPgwApplication::RecvFromGiTunDevice, m_sgwPgwApp));

                   MakeTimeAccessor (&EpcHelper::m_s1uLinkDelay),

  NS_LOG_FUNCTION (this << enb << lteEnbNetDevice);

  NS_ASSERT (enb == lteEnbNetDevice->GetNode ());

  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB after node creation: " << enb->GetObject<Ipv4> ()->GetNInterfaces ());

  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB after installing p2p dev: " << enb->GetObject<Ipv4> ()->GetNInterfaces ());  

  Ipv4InterfaceContainer enbSgwIpIfaces = m_s1uIpv4AddressHelper.Assign (enbSgwDevices);

  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB after assigning Ipv4 addr to S1 dev: " << enb->GetObject<Ipv4> ()->GetNInterfaces ());

  int retval = enbS1uSocket->Bind (InetSocketAddress (enbAddress, m_gtpuUdpPort));

  NS_ASSERT (retval == 0);

  // give PacketSocket powers to the eNB

  //PacketSocketHelper packetSocket;

  //packetSocket.Install (enb); 

  Ptr<Socket> enbLteSocket = Socket::CreateSocket (enb, TypeId::LookupByName ("ns3::PacketSocketFactory"));

  PacketSocketAddress enbLteSocketBindAddress;

  enbLteSocketBindAddress.SetSingleDevice (lteEnbNetDevice->GetIfIndex ());

  retval = enbLteSocket->Bind (enbLteSocketBindAddress);

  NS_ASSERT (retval == 0);  

  PacketSocketAddress enbLteSocketConnectAddress;

  enbLteSocketConnectAddress.SetPhysicalAddress (Mac48Address::GetBroadcast ());

  enbLteSocketConnectAddress.SetProtocol (Ipv4L3Protocol::PROT_NUMBER);

  retval = enbLteSocket->Connect (enbLteSocketConnectAddress);

  NS_ASSERT (retval == 0);  

  NS_LOG_INFO ("create EpcEnbApplication");

  Ptr<EpcEnbApplication> enbApp = CreateObject<EpcEnbApplication> (enbLteSocket, enbS1uSocket, sgwAddress);

  enb->AddApplication (enbApp);

  NS_ASSERT (enb->GetNApplications () == 1);

  NS_ASSERT_MSG (enb->GetApplication (0)->GetObject<EpcEnbApplication> () != 0, "cannot retrieve EpcEnbApplication");

  NS_LOG_LOGIC ("enb: " << enb << ", enb->GetApplication (0): " << enb->GetApplication (0));

EpcHelper::ActivateEpsBearer (Ptr<NetDevice> ueLteDevice, Ptr<NetDevice> enbLteDevice, Ptr<LteTft> tft, uint16_t rnti, uint8_t lcid)

  Ptr<Node> ueNode = ueLteDevice->GetNode (); 

  Ptr<Ipv4> ueIpv4 = ueNode->GetObject<Ipv4> ();

  int32_t interface =  ueIpv4->GetInterfaceForDevice (ueLteDevice);

  NS_ASSERT (interface >= 0);

  NS_ASSERT (ueIpv4->GetNAddresses (interface) == 1);

  Ipv4Address ueAddr = ueIpv4->GetAddress (interface, 0).GetLocal ();

  NS_LOG_LOGIC (" UE IP address: " << ueAddr);

  // NOTE: unlike ueLteDevice, enbLteDevice is NOT an Ipv4 enabled

  // device. In fact we are interested in the S1 device of the eNB.

  // We find it by relying on the assumption that the S1 device is the

  // only Ipv4 enabled device of the eNB besides the localhost interface.

  Ptr<Node> enbNode = enbLteDevice->GetNode (); 

  NS_ASSERT (enbNode != 0);

  Ptr<Ipv4> enbIpv4 = enbNode->GetObject<Ipv4> ();

  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB: " << enbIpv4->GetNInterfaces ());

  // two ifaces total: loopback + the S1-U interface

  NS_ASSERT (enbIpv4->GetNInterfaces () == 2); 

  NS_ASSERT (ueIpv4->GetNAddresses (1) == 1);

  // iface index 0 is loopback, index 1 is the S1-U interface

  Ipv4Address enbAddr = enbIpv4->GetAddress (1, 0).GetLocal (); 

  NS_LOG_LOGIC (" ENB IP address: " << enbAddr);

  // setup S1 bearer at EpcSgwPgwApplication

  uint32_t teid = m_sgwPgwApp->ActivateS1Bearer (ueAddr, enbAddr, tft);

  // setup S1 bearer at EpcEnbApplication

  NS_LOG_LOGIC ("enb: " << enbNode << ", enb->GetApplication (0): " << enbNode->GetApplication (0));

  NS_ASSERT (enbNode->GetNApplications () == 1);

  Ptr<Application> app =  enbNode->GetApplication (0);

  NS_ASSERT (app != 0);

  Ptr<EpcEnbApplication> epcEnbApp = app->GetObject<EpcEnbApplication> ();

  NS_ASSERT (epcEnbApp != 0);

  epcEnbApp->ErabSetupRequest (teid, rnti, lcid);

EpcHelper::GetPgwNode ()

Ipv4InterfaceContainer 

EpcHelper::AssignUeIpv4Address (NetDeviceContainer ueDevices)

  return m_ueAddressHelper.Assign (ueDevices);