latency - Taking 17.x seconds to send 10MB over a 10MB/s link through a switch in ns3 -


i working hang of ns3 , doing sanity check turned out wrong.

i want send 10mb on tcp through switch @ rate of 10mb/s , expect take 1.x seconds because of apparent buggery taking whopping 17.x seconds. can't seem figure out wrong after googling , checking users ns-3 group. if point me in right direction of how debug i'd take answer. btw, if set delay zero, works ten times faster couldn't make sense out of , takes 1.7x seconds.

here enough code reproduce behaviour:

#include <iostream> #include <fstream>  #include "ns3/core-module.h" #include "ns3/network-module.h" #include "ns3/applications-module.h" #include "ns3/bridge-module.h" #include "ns3/csma-module.h" #include "ns3/internet-module.h"  using namespace ns3;  int main (int argc, char *argv[]) {    uint32_t burstsize  = 10000000;   uint32_t packetsize = 1000;    config::setdefault("ns3::tcpsocket::segmentsize", uintegervalue (packetsize));      // create topology's nodes.    nodecontainer nodes;   nodes.create (2);    nodecontainer csmaswitch;   csmaswitch.create (1);    netdevicecontainer nodedevices;   netdevicecontainer switchdevices;    // setting csma attributes                         csmahelper csma;    // setting node's channels   csma.setchannelattribute ("datarate", dataratevalue (datarate ("10mb/s")));   csma.setchannelattribute ("delay", stringvalue ("10ms"));   (int = 0; < 2; i++)     {       netdevicecontainer link = csma.install (nodecontainer (nodes.get (i), csmaswitch));       nodedevices.add (link.get (0));       switchdevices.add (link.get (1));     }    // create bridge netdevice, packet switching   ptr<node> switchnode = csmaswitch.get (0);   bridgehelper bridge;   bridge.install (switchnode, switchdevices);    // add internet protocol stack nodes   config::setdefault ("ns3::tcpl4protocol::sockettype", stringvalue ("ns3::tcpreno"));   internetstackhelper internet;   internet.install (nodes);   internet.install (csmaswitch);    // add ip addresses   ipv4addresshelper ipv4;   ipv4.setbase ("10.1.1.0", "255.255.255.0");   ipv4interfacecontainer nodeinterfaces;   nodeinterfaces = ipv4.assign (nodedevices);    uint16_t port = 10100;   bulksendhelper source ("ns3::tcpsocketfactory",                         inetsocketaddress (nodeinterfaces.getaddress (0), port));    source.setattribute ("maxbytes", uintegervalue (burstsize));   source.setattribute ("sendsize", uintegervalue (packetsize));    applicationcontainer sourceapps = source.install (nodes.get (1));    sourceapps.start (seconds (0.0));   sourceapps.stop (seconds (1000.0));    //   // create packetsinkapplication , install on node 0   //   packetsinkhelper sink ("ns3::tcpsocketfactory",                         inetsocketaddress (ipv4address::getany (), port));   applicationcontainer sinkapps = sink.install (nodes.get (0));   sinkapps.start (seconds (0.0));   sinkapps.stop (seconds (1000.0));    csma.enablepcapall ("results/pcap/data", false);    simulator::run ();   simulator::destroy (); }

the implementation of csma bridge half duplex , that's why performance terrible.


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