发包失败

(gdb) s
ns3::PointToPointNetDevice::Send (this=0x6892e0, packet=..., dest=..., protocolNumber=2048) at ../src/point-to-point/model/point-to-point-net-device.cc:668
668      NS_LOG_FUNCTION (this << packet << dest << protocolNumber);
(gdb) n
669      NS_LOG_LOGIC ("p=" << packet << ", dest=" << &dest);
(gdb)
670      NS_LOG_LOGIC ("UID is " << packet->GetUid ());
(gdb)
676      if (IsLinkUp () == false)
(gdb)
686      AddHeader (packet, protocolNumber);
(gdb)
688      m_macTxTrace (packet);
(gdb)
693      if (m_queue->Enqueue (packet))
(gdb)
698          if (m_txMachineState == READY)
(gdb)
705          return true;
(gdb) p m_txMachineState
$30 = ns3::PointToPointNetDevice::BUSY
(gdb)