ONOS+P4 Tutorial

This directory contains the source code and instructions to run the ONOS+P4 tutorial exercises.

For help, please write to the mailing list brigade-p4@onosproject.org or check the mailing list archives.

Tutorial VM

To complete the exercises, you will need to download and run the following VM (in .ova format):

http://onlab.vicci.org/onos/onos-p4-tutorial.ova

To run the VM you can use any modern virtualization system, although we recommend using VirtualBox. To download VirtualBox and import the VM use the following links:

For more information on the content of the VM, and minimum system requirements, click here.

VM credentials

The VM comes with one user with sudo privileges named sdn with password rocks.

Overview

mytunnel.p4

These exercises are based on a simple P4 program called mytunnel.p4 designed for this tutorial.

To start, have a look a the P4 source code. Even if this is the first time you see P4 code, the program has been commented to provide an understanding of the pipeline behavior to anyone with basic programming and networking background and an high level knowledge of P4. While checking the P4 program, try answering to the following questions:

Which protocol headers are being extracted from each packet?
How can the parser distinguish a packet with MyTunnel encapsulation from one without?
How many match+action tables are defined in the P4 program?
What is the first table in the pipeline applied to every packet?
Which headers can be matched on table t_l2_fwd?
Which type of match is applied to t_l2_fwd? E.g. exact match, ternary, or longest-prefix match?
Which actions can be executed on matched packets?
Which action can be used to send a packet to the controller?
What happens if a matching entry is not found in table t_l2_fwd? What's the next table applied to the packet?

MyTunnel Pipeconf

The mytunnel.p4 program is provided to ONOS as part of a "pipeconf", along with the Java implementations of some ONOS driver behaviors necessary to control this pipeline.

The following Java classes are provided:

PipeconfFactory.java: This class is declared as an OSGi component which is "activated" once the pipeconf application is loaded in ONOS. The main purpose of this class is to instantiate the Pipeconf object and register that with the corresponding service in ONOS. This is where we associate ONOS driver behaviors with the pipeconf, and also define the necessary pipeconf extensions to be able to program and control a BMv2 switch via P4Runtime, namelly the BMv2 JSON configuration and the P4Info file.
PipelineInterpreterImple.java: Implementation of the PipelineInterpreter ONOS driver behavior. The main purpose of this class is to provide a mapping between ONOS constructs and P4 program-specific ones, for example methods to map ONOS well-known header fields and actions to those defined in the P4 program.
PortStatisticsDiscoveryImpl.java: Implementation of the PortStatisticsDiscovery ONOS driver behavior. As the name suggests, this behavior is used to report statistics on the switch ports to ONOS, e.g. number of packets/bytes received and transmitted for each port. This implementation works by reading the value of two P4 counters defined in mytunnel.p4, tx_port_counter and rx_port_counter.

MyTunnel App

This application is used to provide connectivity between each pair of hosts via the MyTunnel protocol. The implementation can be found here.

The application works by registering an host listener with the ONOS Host Service. Every time a new host is discovered, the application creates two unidirectional tunnels between that host and any other host previously discovered.

Tutorial exercises

Exercise 1

Click here to go to this exercise instructions

This exercise shows how to start ONOS and Mininet with BMv2, it also demonstrates connectivity between hosts using the pipeline-agnostic application Reactive Forwarding, in combination with other well known ONOS services such as Proxy ARP, Host Location Provider, and LLDP Link Discovery.

Exercise 2

Click here to go to this exercise instructions

Similar to exercise 1, but here connectivity between hosts is demonstrated using pipeline-specific application "MyTunnel".