# Tutorial 1 - Wired Network

## Overview

This tutorial will cover some use cases when using a wired 2 node
scenario in CORE.

<p align="center">
  <img src="/static/tutorial1/scenario.png" width="75%">
</p>

## Files

Below is the list of files used for this tutorial.

* 2 node wired scenario
    * scenario.xml
    * scenario.py
* 2 node wired scenario, with **n1** running the "Chat App Server" service
    * scenario_service.xml
    * scenario_service.py

## Running this Tutorial

This section covers interactions that can be carried out for this scenario.

Our scenario has the following nodes and addresses:

* n1 - 10.0.0.20
* n2 - 10.0.0.21

All usages below assume a clean scenario start.

### Using Ping

Using the command line utility **ping** can be a good way to verify connectivity
between nodes in CORE.

* Make sure the CORE daemon is running a terminal, if not already
    ``` shell
    sudop core-daemon
    ```
* In another terminal run the GUI
    ``` shell
    core-gui
    ```
* In the GUI menu bar select **File->Open...**, then navigate to and select **scenario.xml**
   <p align="center">
     <img src="/static/tutorial-common/running-open.png" width="75%">
   </p>
* You can now click on the **Start Session** button to run the scenario
   <p align="center">
     <img src="/static/tutorial1/scenario.png" width="75%">
   </p>
* Open a terminal on **n1** by double clicking it in the GUI
* Run the following in **n1** terminal
    ``` shell
    ping -c 3 10.0.0.21
    ```
* You should see the following output
    ``` shell
    PING 10.0.0.21 (10.0.0.21) 56(84) bytes of data.
    64 bytes from 10.0.0.21: icmp_seq=1 ttl=64 time=0.085 ms
    64 bytes from 10.0.0.21: icmp_seq=2 ttl=64 time=0.079 ms
    64 bytes from 10.0.0.21: icmp_seq=3 ttl=64 time=0.072 ms

    --- 10.0.0.21 ping statistics ---
    3 packets transmitted, 3 received, 0% packet loss, time 1999ms
    rtt min/avg/max/mdev = 0.072/0.078/0.085/0.011 ms
    ```

### Using Tcpdump

Using **tcpdump** can be very beneficial for examining a network. You can verify
traffic being sent/received among many other uses.

* Make sure the CORE daemon is running a terminal, if not already
    ``` shell
    sudop core-daemon
    ```
* In another terminal run the GUI
    ``` shell
    core-gui
    ```
* In the GUI menu bar select **File->Open...**, then navigate to and select **scenario.xml**
   <p align="center">
     <img src="/static/tutorial-common/running-open.png" width="75%">
   </p>
* You can now click on the **Start Session** button to run the scenario
   <p align="center">
     <img src="/static/tutorial1/scenario.png" width="75%">
   </p>
* Open a terminal on **n1** by double clicking it in the GUI
* Open a terminal on **n2** by double clicking it in the GUI
* Run the following in **n2** terminal
    ``` shell
    tcpdump -lenni eth0
    ```
* Run the following in **n1** terminal
    ``` shell
    ping -c 1 10.0.0.21
    ```
* You should see the following in **n2** terminal
    ``` shell
    tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
    listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
    10:23:04.685292 00:00:00:aa:00:00 > 00:00:00:aa:00:01, ethertype IPv4 (0x0800), length 98: 10.0.0.20 > 10.0.0.21: ICMP echo request, id 67, seq 1, length 64
    10:23:04.685329 00:00:00:aa:00:01 > 00:00:00:aa:00:00, ethertype IPv4 (0x0800), length 98: 10.0.0.21 > 10.0.0.20: ICMP echo reply, id 67, seq 1, length 64
    ```

### Editing a Link

You can edit links between nodes in CORE to modify loss, delay, bandwidth, and more. This can be
beneficial for understanding how software will behave in adverse conditions.

* Make sure the CORE daemon is running a terminal, if not already
    ``` shell
    sudop core-daemon
    ```
* In another terminal run the GUI
    ``` shell
    core-gui
    ```
* In the GUI menu bar select **File->Open...**, then navigate to and select **scenario.xml**
   <p align="center">
     <img src="/static/tutorial-common/running-open.png" width="75%">
   </p>
* You can now click on the **Start Session** button to run the scenario
   <p align="center">
     <img src="/static/tutorial1/scenario.png" width="75%">
   </p>
* Right click the link between **n1** and **n2**
* Select **Configure**
  <p align="center">
    <img src="/static/tutorial1/link-config.png" width="75%">
  </p>
* Update the loss to **25**
  <p align="center">
    <img src="/static/tutorial1/link-config-dialog.png" width="50%">
  </p>
* Open a terminal on **n1** by double clicking it in the GUI
* Run the following in **n1** terminal
    ``` shell
    ping -c 10 10.0.0.21
    ```
* You should see something similar for the summary output, reflecting the change in loss
    ``` shell
    --- 10.0.0.21 ping statistics ---
    10 packets transmitted, 6 received, 40% packet loss, time 9000ms
    rtt min/avg/max/mdev = 0.077/0.093/0.108/0.016 ms
    ```
* Remember that the loss above is compounded, since a ping and the loss applied occurs in both directions

### Running Software

We will now leverage the installed Chat App software to stand up a server and client
within the nodes of our scenario.

* Make sure the CORE daemon is running a terminal, if not already
    ``` shell
    sudop core-daemon
    ```
* In another terminal run the GUI
    ``` shell
    core-gui
    ```
* In the GUI menu bar select **File->Open...**, then navigate to and select **scenario.xml**
   <p align="center">
     <img src="/static/tutorial-common/running-open.png" width="75%">
   </p>
* You can now click on the **Start Session** button to run the scenario
   <p align="center">
     <img src="/static/tutorial1/scenario.png" width="75%">
   </p>
* Open a terminal on **n1** by double clicking it in the GUI
* Run the following in **n1** terminal
    ``` shell
    export PATH=$PATH:/usr/local/bin
    chatapp-server
    ```
* Open a terminal on **n2** by double clicking it in the GUI
* Run the following in **n2** terminal
    ``` shell
    export PATH=$PATH:/usr/local/bin
    chatapp-client -a 10.0.0.20
    ```
* You will see the following output in **n1** terminal
    ``` shell
    chat server listening on: :9001
    [server] 10.0.0.21:44362 joining
    ```
* Type the following in **n2** terminal and hit enter
    ``` shell
    hello world
    ```
* You will see the following output in **n1** terminal
    ``` shell
    chat server listening on: :9001
    [server] 10.0.0.21:44362 joining
    [10.0.0.21:44362] hello world
    ```

### Tailing a Log

In this case we are using the service based scenario. This will automatically start
and run the Chat App Server on **n1** and log to a file. This case will demonstrate
using `tail -f` to observe the output of running software.

* Make sure the CORE daemon is running a terminal, if not already
    ``` shell
    sudop core-daemon
    ```
* In another terminal run the GUI
    ``` shell
    core-gui
    ```
* In the GUI menu bar select **File->Open...**, then navigate to and select **scenario_service.xml**
   <p align="center">
     <img src="/static/tutorial-common/running-open.png" width="75%">
   </p>
* You can now click on the **Start Session** button to run the scenario
   <p align="center">
     <img src="/static/tutorial1/scenario.png" width="75%">
   </p>
* Open a terminal on **n1** by double clicking it in the GUI
* Run the following in **n1** terminal
    ``` shell
    tail -f chatapp.log
    ```
* Open a terminal on **n2** by double clicking it in the GUI
* Run the following in **n2** terminal
    ``` shell
    export PATH=$PATH:/usr/local/bin
    chatapp-client -a 10.0.0.20
    ```
* You will see the following output in **n1** terminal
    ``` shell
    chat server listening on: :9001
    [server] 10.0.0.21:44362 joining
    ```
* Type the following in **n2** terminal and hit enter
    ``` shell
    hello world
    ```
* You will see the following output in **n1** terminal
    ``` shell
    chat server listening on: :9001
    [server] 10.0.0.21:44362 joining
    [10.0.0.21:44362] hello world
    ```

--8<-- "tutorials/common/grpc.md"