HOWTO Use Linux Containers to set up virtual networks
Main Page - Current Development - Developer FAQ - Tools - Related Projects - Project Ideas - Summer Projects
Installation - Troubleshooting - User FAQ - HOWTOs - Samples - Models - Education - Contributed Code - Papers
One of the interesing ways ns-3 simulations can be integrated with real hardware is to create a simulated network and use "real" hosts to drive the network. Often, the number of real hosts is relatively large, and so acquiring that number of real computers would be prohibitively expensive. It is possible to use virtualization technology to create software implementations, called virtual machines, that execute software as if they were real hosts. If you have not done so, we recommend going over HOWTO make ns-3 interact with the real world to review your options.
This HOWTO discusses how one would configure and use a modern Linux system (e.g., Fedora 12) to run ns-3 systems using paravirtualization of resources with Linux Containers (lxc).
HOWTO Use Linux Containers to set up virtual networks
Background
Always know your tools. In this context, the first step for those unfamiliar with Linux Containers is to get an idea of what it is we are talking about and where they live. Linux Containers, also called "lxc tools," are a relatively new feature of Linux as of this writing. They are an offshoot of what are called "chroot jails." A quick explanation of the FreeBSD version can be found here. It may be worth a quick read before continuing to help you understand some background and terminology better.
If you peruse the web looking for references to Linux Containers, you will find that much of the existing documentation is based on this document. This is a rather low-level document, more of a reference than a HOWTO that makes Linux Containers actually look more complicated than they are to get started with. IBM DeveloperWorks provides what they call a "tour and setup" document; but I find this document a little too abstract and high-level.
In this HOWTO, we will attempt to bridge the gap and give you a "just-right" presentation of Linux Containers and ns-3 that should get you started doing useful work without damaging too many brain cells.
We assume that you have a kernel that supports Linux Containers installed and configured on your host system. Fedora 12 comes with Linux Containers enabled "out of the box" and we assume you are running that system. Details of the HOWTO may vary if you are using a system other than Fedora 12
Get and Understand the Linux Container Tools
The first step in the process is to get the Linux Container Tools onto your system. Although the Fedora 12 system comes with Linux Containers enabled, it does not necessarily have the user tools installed. You will need to install these tools, and also make sure you have the ability to create and configure bridges, and the ability to create and configure tap devices. If you are a sudoer, you can type the following to install the required tools.
sudo yum install lxc bridge-utils tunctl
To see a summary of the Linux Container tool (lxc), you can now begin looking at man pages. The place to star is with the lxc man page. Give that a read, keeping in mind that some details are not relevant at this time. Feel free to ignore the parts about kernel requirements and configuration and ssh daemons. So go ahead and do,
man lxc
and have a read.
The one configuration step you may have to do on Fedora 12 is to mount a cgroup directory. This directory does not exist by default, so if you are the fist user to need that support you will have to create the directory and mount it. Getting all of this to work will be easier if you are root, so we will assume you have this kind of privilege. Go ahead and create teh cgroup directory and mount it. This is done by,
su mkdir /cgroup mount -t cgroup cgroup /cgroup
If you want to make this mount persistent, you will have to edit fstab.
Craigdo 17:47, 17 February 2010 (UTC)
