# P4 Tutorial

## Introduction

Welcome to the P4 Tutorial! We've prepared a set of exercises to help
you get started with P4 programming, organized into several modules:

1. Introduction and Language Basics
* [Basic Forwarding](./exercises/basic)
* [Basic Tunneling](./exercises/basic_tunnel)

2. P4Runtime and the Control Plane
* [P4Runtime](./exercises/p4runtime)

3. Monitoring and Debugging
* [Explicit Congestion Notification](./exercises/other/ecn)
* [Multi-Hop Route Inspection](./exercises/mri)

4. Advanced Behavior
* [Source Routing](./exercises/source_routing)
* [Calculator](./exercises/other/calc)
* [Load Balancing](./exercises/load_balance)

## Presentation 

The slides are available [online](http://bit.ly/p4d2-2018-spring) and
in the P4_tutorial.pdf in the tutorial directory.

A P4 Cheat Sheet is also available [online](https://drive.google.com/file/d/1Z8woKyElFAOP6bMd8tRa_Q4SA1cd_Uva/view?usp=sharing)
which contains various examples that you can refer to.
        
## Obtaining required software

If you are starting this tutorial at the Spring 2018 P4 Developer Day,
then we've already provided you with a virtual machine that has all of
the required software installed.

Otherwise, to complete the exercises, you will need to either build a
virtual machine or install several dependencies.

To build the virtual machine:
- Install [Vagrant](https://vagrantup.com) and [VirtualBox](https://virtualbox.org)
- Clone the repository
- `cd vm`
- `vagrant up`
- Log in with username `p4` and password `p4` and issue the command `sudo shutdown -r now`
- When the machine reboots, you should have a graphical desktop machine with the required
software pre-installed.

*Note: Before running the `vagrant up` command, make sure you have enabled virtualization in your environment; otherwise you may get a "VT-x is disabled in the BIOS for both all CPU modes" error. Check [this](https://stackoverflow.com/questions/33304393/vt-x-is-disabled-in-the-bios-for-both-all-cpu-modes-verr-vmx-msr-all-vmx-disabl) for enabling it in virtualbox and/or BIOS for different system configurations.

You will need the script to execute to completion before you can see the `p4` login on your virtual machine's GUI. In some cases, the `vagrant up` command brings up only the default `vagrant` login with the password `vagrant`. Dependencies may or may not have been installed for you to proceed with running P4 programs. Please refer the existing issues to help fix your problem or create a new one if your specific problem isn't addressed there.*

To install dependencies by hand, please reference the [vm](../vm) installation scripts.
They contain the dependencies, versions, and installation procedure.
You should be able to run them directly on an Ubuntu 16.04 machine, although note that the scripts currently assume the existence of a directory `/home/vagrant`:
- `sudo ./root-bootstrap.sh`
- `sudo ./user-bootstrap.sh`
