# 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/ecn)
* [Multi-Hop Route Inspection](./exercises/mri)

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

5. Stateful Packet Processing
* [Firewall](./exercises/firewall)
* [Link Monitoring](./exercises/link_monitor)

## 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 one of the proctored tutorial events,
then we've already provided you with a virtual machine that has all of
the required software installed. Ask an instructor for a USB stick with
the VM image.

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
- Before proceeding, ensure that your system has at least 25 Gbytes of free disk space, otherwise the installation can fail in unpredictable ways.
- `cd vm`
- `vagrant up` - This step typically takes over 1 hour to complete, and requires a reliable Internet connection throughout.
- When the machine reboots, you should have a graphical desktop machine with the required software pre-installed.  There are two user accounts on the VM, `vagrant` (password `vagrant`) and `p4` (password `p4`).  The account `p4` should be logged in when the VM boots up by default, and is the one you are expected to use.

*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](https://github.com/p4lang/tutorials/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:
- `sudo ./root-bootstrap.sh`
- `sudo ./user-bootstrap.sh`