NS3 network Emulation (4): Datarate Property

Happy Shrimp

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Welcome reprint, but please keep the author information

in the first.py creates a point-to-point channel and has two properties configured:

Pointtopoint = Ns.point_to_point. Pointtopointhelper () Pointtopoint.setdeviceattribute ("Datarate", Ns.core.StringValue ("2Mbps")) Pointtopoint.setchannelattribute ("Delay", Ns.core.StringValue ("100ms"))

in the configurationdataratewhen thefirst.pyA string was passed"2Mbps", this string is finally represented by the followingC + +code to parse:

Booldatarate::D oparse (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 = = "MbS ") {//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;}

from this piece of code it is also evident that NS3 The expression of the medium rate string and its significance, more clear than the document, it is not known that the rate can have so many ways of expression, Khan a ~~~~

from "Datarate" a few other device properties can be found:

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 and point mode", B Ooleanvalue (False), Makebooleanaccessor (&simplenetdevice::m_pointtopointmode), M Akebooleanchecker ()). AddAttribute ("Txqueue", "A queue to use as the transmit queue in the device.", String          Value ("NS3::D roptailqueue"), 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 (&si mplenetdevice::m_bps), Makedataratechecker ()).                     Addtracesource ("Phyrxdrop", "Trace source indicating a packet has been dropped"                     "By the device during reception", Maketracesourceaccessor (&simplenetdevice::m_phyrxdroptrace),  "NS3::P acket::tracedcallback"); return TID;}

It's just that we don't care about these properties for now.

Modifydataratevalue that can be found in theNetanimThe most obvious manifestation of this is the length of the arrow that represents the packet, whendatarateto be2MbpsWhen:

when datarate into 200Kbps when it becomes:

The difference is still very obvious!

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NS3 network Emulation (4): Datarate Property