Tutorial 1 - Wired Network

Overview

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

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
```
sudo core-daemon
```
In another terminal run the GUI
```
core-gui
```
In the GUI menu bar select File->Open..., then navigate to and select scenario.xml
You can now click on the Start Session button to run the scenario
Open a terminal on n1 by double clicking it in the GUI
Run the following in n1 terminal
```
ping -c 3 10.0.0.21
```

You should see the following output

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
```
sudo core-daemon
```
In another terminal run the GUI
```
core-gui
```
In the GUI menu bar select File->Open..., then navigate to and select scenario.xml
You can now click on the Start Session button to run the scenario
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
```
tcpdump -lenni eth0
```
Run the following in n1 terminal
```
ping -c 1 10.0.0.21
```

You should see the following in n2 terminal

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
```
sudo core-daemon
```
In another terminal run the GUI
```
core-gui
```
In the GUI menu bar select File->Open..., then navigate to and select scenario.xml
You can now click on the Start Session button to run the scenario
Right click the link between n1 and n2
Select Configure
Update the loss to 25
Open a terminal on n1 by double clicking it in the GUI
Run the following in n1 terminal
```
ping -c 10 10.0.0.21
```

You should see something similar for the summary output, reflecting the change in loss

--- 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
```
sudo core-daemon
```
In another terminal run the GUI
```
core-gui
```
In the GUI menu bar select File->Open..., then navigate to and select scenario.xml
You can now click on the Start Session button to run the scenario
Open a terminal on n1 by double clicking it in the GUI

Run the following in n1 terminal

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

export PATH=$PATH:/usr/local/bin
chatapp-client -a 10.0.0.20

You will see the following output in n1 terminal

chat server listening on: :9001
[server] 10.0.0.21:44362 joining

Type the following in n2 terminal and hit enter
```
hello world
```

You will see the following output in n1 terminal

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
```
sudo core-daemon
```
In another terminal run the GUI
```
core-gui
```
In the GUI menu bar select File->Open..., then navigate to and select scenario_service.xml
You can now click on the Start Session button to run the scenario
Open a terminal on n1 by double clicking it in the GUI
Run the following in n1 terminal
```
tail -f chatapp.log
```
Open a terminal on n2 by double clicking it in the GUI

Run the following in n2 terminal

export PATH=$PATH:/usr/local/bin
chatapp-client -a 10.0.0.20

You will see the following output in n1 terminal

chat server listening on: :9001
[server] 10.0.0.21:44362 joining

Type the following in n2 terminal and hit enter
```
hello world
```

You will see the following output in n1 terminal

chat server listening on: :9001
[server] 10.0.0.21:44362 joining
[10.0.0.21:44362] hello world

gRPC Python Scripts

You can also run the same steps above, using the provided gRPC script versions of scenarios. Below are the steps to run and join one of these scenario, then you can continue with the remaining steps of a given section.

Make sure the CORE daemon is running a terminal, if not already
```
sudo core-daemon
```
From another terminal run the tutorial python script, which will create a session to join
```
/opt/core/venv/bin/python scenario.py
```
In another terminal run the CORE GUI
```
core-gui
```
You will be presented with sessions to join, select the one created by the script