Engineering Clinic

This post shows how to install ns 3.34 in Ubuntu 20.04 LTS Prerequisites: Fresh installation of Ubuntu Version 20.04 LTS  ns3.34 can be downloaded from here Follow the video link for complete step by step instructions on the installation.  This version fixes the compilation issues of vanet-routing-compare.cc (bug in ns3.33)  Issue the following commands after opening a terminal  $ sudo apt update $ sudo apt install g++ python3 python3-dev python-dev pkg-config sqlite3 python3-setuptools git qt5-default gir1.2-goocanvas-2.0 python3-gi python3-gi-cairo python3-pygraphviz gir1.2-gtk-3.0 ipython3 openmpi-bin openmpi-common openmpi-doc libopenmpi-dev autoconf cvs bzr unrar openmpi-bin openmpi-common openmpi-doc libopenmpi-dev tcpdump wireshark libxml2 libxml2-dev Unzip or untar the ns-allinone-3.34.tar.bz2 in the home folder (in my case its /home/pradeepkumar) $ cd ns-allinone-3.34/ $ ./build.py --enable-examples --enable-tests  Once the installation is completed, you may get an output show

In network simulator 3, while simulating the vanet-routing-compare.cc file, you may get an error in ns-3.33 version as shown below: msg="GlobalValue name=VRCcumulativeBsmCaptureStart: input value is not a string",  file=../src/core/model/global-value.cc, line=128 terminate called without an active exception Command ['/home/ns3/Desktop/ns-allinone-3.33/ns-3.33/build/scratch/vanet-routing-compare'] terminated with signal SIGIOT. Run it under a debugger to get more information (./waf --run <program> --gdb"). To overcome this error, here is the patch to download https://github.com/tspradeepkumar/ns3/blob/main/vanet.patch Once downloaded, move this file to  ~ns-3.33/scratch/ folder and copy the vanet-routing-compare.cc also to the scratch/ folder and apply the following command  $ cd ns-allinone-3.33/ns-3.33/scratch $ patch -p0 < vanet.patch vanet-routing-compare.cc  Check the following video for explanation of vanet-routing-compare.cc and its characteristics

This post shows you Simple MQTT Application using Node JS. There are three parts of the application. For running any MQTT application, we need a  1. Broker (The broker can be anywhere in the Internet or cloud or a local machine)  2. Publisher (pub.js is the name of the file) 3. Subscriber (sub.js is the name of the file) Check the following video for complete instructions. In this example, we will be using a broker called https://www.hivemq.com To use the cloud broker ( mqtt://broker.hivemq.com) and connect the publisher and subscriber with a topic and a message. To install the Hive MQ software in your local machine (127.0.0.1) and run the same above code locally and make the connectivity between the pub-sub. We open two new .js files called pub.js (publisher) and sub.js (subscriber) in Visual Studio Code. To install the mqtt module in NodeJS, we use the command “ npm install mqtt ” in C:/ terminal.  We define our client as connecting to “mqtt://broker.hivemq.com”. We connect to th