Tassen: Next-Generation BNG CUPS API

This project aims at defining an API for BNG Control and User Plane Separation (CUPS) based on next-generation SDN interfaces such as P4Runtime, gNMI, and OpenConfig.

Tassen is a German word for "cups".

Requirements

To build and test the Tassen API you will need the following software to be installed on your machine:

• Docker
• make

Docker is used to run the necessary tools without worrying about additional dependencies. Before starting, make sure to fetch all the required Docker images:

make deps

Content

Reference BNG-UP P4 Implementation

The directory p4src contains bng.p4, the P4 program defining the reference packet forwarding pipeline of a BNG user plane (BNG-UP) abstracted by the Tassen API.

[DC] test text.

The goal of this P4 program is twofold:

1. formally define the forwarding model of a BNG-UP;
2. implicitly define the runtime API that a BNG control plane (BNG-CP) can use to manipulate the forwarding state of a BNG-UP.

To build the P4 program:

make p4

To generate the P4 graphs:

make graph

Packet-based Unit Tests

The directory ptf contains unit tests for the P4 program. Tests use PTF, a Python-based framework for data plane testing, and stratum_bmv2, the reference P4 software switch (BMv2 simple_switch) built with Stratum support to provide a P4Runtime and gNMI server interface.

To run all test cases:

make check

ptf/tests contains the actual test case implementation, organized in modules, e.g., upstream.py for all test cases pertaining the upstream functionality, packetio.py for control packet I/O, etc.

To run all tests in a module:

make check TEST=<MODULE>

To run a specific test case:

make check TEST=<MODULE>.<TEST NAME>

For example:

make check TEST=packetio.PacketOutTest

To run all tests, except that of a specific module (e.g., accounting)

make check TEST="all ^accounting"

ptf/lib contains the test runner as well as libraries useful to simplify the test case implementations (e.g., helper.py provides a P4Info helper with methods convenient to construct P4Runtime table entries).

Runtime Mapping to Target BNG-UP Implementations

The directory mapr contains the reference implementation of the runtime logic to translate P4Runtime RPCs for the logical P4 program (bng.p4) to target-specific ones.

mapr is written in Go.

To build mapr:

make mapr

This command will produce a binary in mapr/mapr that can be used as part of the PTF tests.

mapr currently provides the translation logic for different targets, such as:

• dummy: for testing purposes only, where the target device runs with the same Tassen logical pipeline, and P4Runtime RPCs are relayed as-is, with no translation.
• fabric: for a switch running ONF's fabric.p4 (fabric-bng profile) which is optimized for Intel Barefoot Tofino.

To run PTF tests on a given target together with mapr:

make check-<target> TEST=<filters>

For example, to run all PTF tests on the dummy target:

make check-dummy TEST=all

Continuous Integration

This repository is configured with a CircleCI job that checks code changes by:

• building logical P4 program (bng.p4) for BMv2;
• running tests on different targets.

The job configuration can be found in .circleci/config.yml.

Currently, we check the following targets:

Target	Tests	Notes
self	all	Tests executed without mapr
dummy	all
fabric	all ^accounting	Accounting not supported on fabric.p4, yet.

The current status for the master branch is: