Switchyard is a library and framework for implementing software-based networked systems in Python such as Ethernet switches, IP routers, middleboxes, and end-host protocol stacks. It is primarily intended for educational use and supports creating devices from layer 2 (link layer) all the way through the application layer.
Documentation is available at http://cs.colgate.edu/~jsommers/switchyard. Documentation is written using the Python Sphinx package; doc sources are available in the documentation directory.
Switchyard can run in a standalone test harness mode or can also use "live" network interfaces on a Linux or macOS host. It works nicely within Mininet and other virtual host environments, too.
The version of Switchyard on the master branch is a major revision of the code as of the end of 2016. This is the second major overhaul. The earliest working version of Switchyard (from late 2013) can be found on the v1 branch, and the subsequent rewrite (through the end of 2016) can be found on the v2 branch. Beware that the current version of Switchyard is backward incompatible with previous versions and many parts of the code are under active development. As with the last major version of Switchyard, this one requires Python 3.4, at minimum.
Prequisites: you'll also likely need to install additional packages (do this before using pip to install the Python libraries) on different operating systems:
- Fedora (20 and later):
sudo yum install libffi-devel libpcap-devel python3-devel python3-pip python3-virtualenv- FreeBSD (10.3):
pkg install libffi libpcap- macOS: install libffi and libpcap through mac Homebrew (https://brew.sh)
- Ubuntu (14.04 and later):
sudo apt-get install libffi-dev libpcap-dev python3-dev python3-pip python3-venv
You can install Switchyard and the necessary related packages in an isolated Python virtual environment ("venv"), which is the recommended path, or in the system directories, which is often less desirable. The venv route is highly suggested, since it makes all installation "local" and can easily destroyed, cleaned up, and recreated.
To create a new virtual environment, you could do something like the following:
$ python3 -m venv syenv
You can change the name syenv to whatever you'd like to name your virtual environment. Next, you need to activate the environment. The instructions vary depending on the shell you're using. On bash, the command is:
$ source ./syenv/bin/activate
You'll need to replace syenv with whatever you named the virtual environment. If you're using a different shell than bash, refer to Python documentation on the venv module.
Finally, install Switchyard. All the required additional libraries should be automatically installed, too.
$ python3 -m pip install switchyard
Results of tests run in Travis (on Ubuntu):
- Documentation sources can be found in the documentation directory. See http://cs.colgate.edu/~jsommers/switchyard for compiled/built docs in HTML.
- Sample exercises (in ReStructuredText format) can be found in the examples/exercises directory. The examples are not included with the Switchyard package that is installed through
- Instructor-only materials such as test scenarios and other scripts available on request (jsommers@colgate.edu); they're in a separate private repository.
I gratefully acknowledge support from the National Science Foundation. The materials here are based upon work supported by the NSF under grant CNS-1054985 ("CAREER: Expanding the functionality of Internet routers").
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.
Copyright 2015-2017 Joel Sommers. All rights reserved.
The Switchyard software is distributed under terms of the GNU General Public License, version 3. See below for the standard GNU GPL v3 copying text.
Switchyard's documentation is distributed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License: http://creativecommons.org/licenses/by-nc-sa/4.0/.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.