This directory includes P4 code samples, meant to be run on bmv2, which illustrates several more advanced features of P4. The following samples are included:

copy_to_cpu: how to use the clone_ingress_to_egress primitive to clone the packet, encapsulate it and send it to a special port.
meter: how to use indirect meters in P4.
TLV_parsing: how to parse IPv4 options
register: how to use registers in P4 and read / write the state from the control plane
counter: how to use counters in P4
action_profile: how to use action profiles in P4, using ECMP as support
resubmit: how to resubmit packets to the ingress pipelines
simple_nat: a basic implementation of a full-cone NAT for TCP traffic

All examples are orgranized the same way, with a p4src directory containing the P4 source code, and a README file describing the P4 program and explaining how to run a quick demonstration.

Obtaining required software

To complete the exercises, you will need to clone 2 p4lang Github repositories and install their dependencies. To clonde the repositories:

git clone https://github.com/p4lang/behavioral-model.git bmv2
git clone https://github.com/p4lang/p4c-bm.git p4c-bmv2

The first repository (bmv2) is the second version of the behavioral model. It is a C++ software switch that will behave according to your P4 program. The second repository (p4c-bmv2) is the compiler for the behavioral model: it takes P4 program and output a JSON file which can be loaded by the behavioral model.

Each of these repositories come with dependencies. p4c-bmv2 is a Python repository and installing the required Python dependencies is very easy to do using pip: sudo pip install -r requirements.txt.

bmv2 is a C++ repository and has more external dependencies. They are listed in the README. If you are running Ubuntu 14.04+, the dependencies should be easy to install (you can use the install_deps.sh script that comes with bmv2). Do not forget to build the code once all the dependencies have been installed:

./autogen.sh
./configure
make

Before starting the exercises

You need to tell us where you cloned the bmv2 and p4c-bm repositories :). Please update the values of the shell variables BMV2_PATH and P4C_BM_PATH in the env.sh file - located in the root directory of this repository. Note that if you cloned both repositories in the same directory as this one (tutorials), you will not need to change the value of the variables.

You will also need to run the veth_setup.sh script included in this directory as sudo to setup the veth interfaces needed by the switch.

That's all :)