NS3网络仿真之：DataRate属性-白红宇的个人博客

发布日期：2021-06-03 08:57:32 浏览次数：7 分类：技术文章

本文共 6145 字，大约阅读时间需要 20 分钟。

前言序锦

本非通信人，却也来瞧瞧这通信的奇妙！由于SRTP项目选的是通信的项目，所以这段时间，也一直在接触与NS3相关的知识，进他就来和大家简单聊一下……

正文

首先我们需要在first.py文件中创建一个点到点的信道，并配置来两个属性：

PointToPoint = ns.point_to_point.PointToPointHelper()pointToPoint.SetDeviceAttribute("DataRate", ns.core.StringValue("10Mbps"))pointToPoint.SetChannelAttribute("Delay", ns.core.StringValue("100ms"))

上面的代码我们配置了DataRate的属性时，first.py传递来一个字符串“10Mbps”（同时给“Delay”属性值传递来一个字符串”100ms“，这是传入来一个延时，这个不作讨论），这个字符串最后通过C++代码来进行解析：

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;  }

从这段代码我们可以很明显的看出，NS3中速率的字符串的表达方式以及其意义

- 我们通过“DataRate”这个属性来看，可以发现其他几个设备的属性，在这里顺便讲一下：

SimpleNetDevice::GetTypeId (void)  {    static TypeId tid = TypeId ("ns3::SimpleNetDevice")      .SetParent
   
     ()      .SetGroupName("Network")       .AddConstructor
    
      ()      .AddAttribute ("ReceiveErrorModel",                     "The receiver error model used to simulate packet loss",                     PointerValue (),                     MakePointerAccessor (&SimpleNetDevice::m_receiveErrorModel),                     MakePointerChecker
     
       ())      .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
      
        ())      .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;  }

这也是NS3仿真过程几个比较重要的属性，后面我们会有详细的介绍，这里找出来让大家一起去探讨……