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NS3网络仿真(4): DataRate属性
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http://blog.csdn.net/lights_joy/
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在first.py中创建了一个点到点的信道,且配置了两个属性:
pointToPoint = ns.point_to_point.PointToPointHelper() pointToPoint.SetDeviceAttribute("DataRate", ns.core.StringValue("2Mbps")) pointToPoint.SetChannelAttribute("Delay", ns.core.StringValue("100ms"))
在配置DataRate时。first.py传递了一个字符串”2Mbps”。这个字符串最后由以下的C++代码进行解析:
bool DataRate::DoParse (const std::string s, uint64_t *v) { NS_LOG_FUNCTION (s << v); std::string::size_type n = s.find_first_not_of ("0123456789."); if (n != std::string::npos) { // Found non-numeric std::istringstream iss; iss.str (s.substr (0, n)); double r; iss >> r; std::string trailer = s.substr (n, std::string::npos); if (trailer == "bps") { // bit/s *v = (uint64_t)r; } else if (trailer == "b/s") { // bit/s *v = (uint64_t)r; } else if (trailer == "Bps") { // byte/s *v = (uint64_t)(r * 8); } else if (trailer == "B/s") { // byte/s *v = (uint64_t)(r * 8); } else if (trailer == "kbps") { // kilobits/s *v = (uint64_t)(r * 1000); } else if (trailer == "kb/s") { // kilobits/s *v = (uint64_t)(r * 1000); } else if (trailer == "Kbps") { // kilobits/s *v = (uint64_t)(r * 1000); } else if (trailer == "Kb/s") { // kilobits/s *v = (uint64_t)(r * 1000); } else if (trailer == "kBps") { // kiloByte/s *v = (uint64_t)(r * 8000); } else if (trailer == "kB/s") { // KiloByte/s *v = (uint64_t)(r * 8000); } else if (trailer == "KBps") { // kiloByte/s *v = (uint64_t)(r * 8000); } else if (trailer == "KB/s") { // KiloByte/s *v = (uint64_t)(r * 8000); } else if (trailer == "Kib/s") { // kibibit/s *v = (uint64_t)(r * 1024); } else if (trailer == "KiB/s") { // kibibyte/s *v = (uint64_t)(r * 8192); } else if (trailer == "Mbps") { // MegaBits/s *v = (uint64_t)(r * 1000000); } else if (trailer == "Mb/s") { // MegaBits/s *v = (uint64_t)(r * 1000000); } else if (trailer == "MBps") { // MegaBytes/s *v = (uint64_t)(r * 8000000); } else if (trailer == "MB/s") { // MegaBytes/s *v = (uint64_t)(r * 8000000); } else if (trailer == "Mib/s") { // MebiBits/s *v = (uint64_t)(r * 1048576); } else if (trailer == "MiB/s") { // MebiByte/s *v = (uint64_t)(r * 1048576 * 8); } else if (trailer == "Gbps") { // GigaBit/s *v = (uint64_t)(r * 1000000000); } else if (trailer == "Gb/s") { // GigaBit/s *v = (uint64_t)(r * 1000000000); } else if (trailer == "GBps") { // GigaByte/s *v = (uint64_t)(r * 8*1000000000); } else if (trailer == "GB/s") { // GigaByte/s *v = (uint64_t)(r * 8*1000000000); } else if (trailer == "Gib/s") { // GibiBits/s *v = (uint64_t)(r * 1048576 * 1024); } else if (trailer == "GiB/s") { // GibiByte/s *v = (uint64_t)(r * 1048576 * 1024 * 8); } else { return false; } return true; } std::istringstream iss; iss.str (s); iss >> *v; return true; }
从这一段代码也能够明显看出NS3中速率字符串的表达方式及意义,比文档清晰多了,原来还不知道速率能够有这么多的表达方式,汗一个~~~~
从”DataRate”顺藤摸瓜。能够发现其他几个设备属性:
TypeId SimpleNetDevice::GetTypeId (void) { static TypeId tid = TypeId ("ns3::SimpleNetDevice") .SetParent<NetDevice> () .SetGroupName("Network") .AddConstructor<SimpleNetDevice> () .AddAttribute ("ReceiveErrorModel", "The receiver error model used to simulate packet loss", PointerValue (), MakePointerAccessor (&SimpleNetDevice::m_receiveErrorModel), MakePointerChecker<ErrorModel> ()) .AddAttribute ("PointToPointMode", "The device is configured in Point to Point mode", BooleanValue (false), MakeBooleanAccessor (&SimpleNetDevice::m_pointToPointMode), MakeBooleanChecker ()) .AddAttribute ("TxQueue", "A queue to use as the transmit queue in the device.", StringValue ("ns3::DropTailQueue"), MakePointerAccessor (&SimpleNetDevice::m_queue), MakePointerChecker<Queue> ()) .AddAttribute ("DataRate", "The default data rate for point to point links. Zero means infinite", DataRateValue (DataRate ("0b/s")), MakeDataRateAccessor (&SimpleNetDevice::m_bps), MakeDataRateChecker ()) .AddTraceSource ("PhyRxDrop", "Trace source indicating a packet has been dropped " "by the device during reception", MakeTraceSourceAccessor (&SimpleNetDevice::m_phyRxDropTrace), "ns3::Packet::TracedCallback") ; return tid; }
仅仅只是我们眼下暂且无论这些属性。
改动DataRate的值。能够发如今NetAnim中最明显的表现就是用以表示数据包的箭头的长度,当DataRate为2Mbps时:
当DataRate变为200Kbps时就变成了:
区别还是非常明显的!
??
NS3网络仿真(4): DataRate属性
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