Mininet 2.2.0 Release Notes

Additional details on the 2.2.0 release are available in the release announcement, the README file, and the Mininet documentation.

To download Mininet, visit http://mininet.org/download for pre-built VM images and github (or code.mininet.org) for the source code.

This document contains supplementary information and issues.

Documentation for Examples and Tests

The examples have Python docstring documentation, and can be used as modules, e.g.

sudo python -m mininet.examples.nat

Their components may also be imported, but they should be considered volatile and not part of the official Mininet API. Since they're not part of the official API, their documentation is also not currently included at api.mininet.org or generated with make doc. However, you may wish to look at the code and README.md file in the examples/ directory.

The tests are not included in the Mininet .egg, but they are provided in the Mininet source tree.

Potential VirtualBox/VM Issues and Solutions

• If VirtualBox (or any other virtual machine monitor) cannot import the .ovf directly, try creating a new VM using the .vmdk file as its disk.

• VirtualBox may complain about missing hardware on initial import - you may safely ignore this message.

• We've added a symlink to the top-level examples directory from the mininet code directory to make examples importable. If you are using VirtualBox and clone the repository to a shared folder, the symlink will be broken. This is because VirtualBox does not allow guests to create symlinks in shared folders by default for security reasons. To enable symlink creation, you should do the following:

  • Shut down your VM and quit the VirtualBox Manager
  • Run the following command on your host OS: VBoxManage setextradata VM_NAME VBoxInternal2/SharedFoldersEnableSymlinksCreate/SHARE_NAME 1
  • Restart your VM

Test / Hi-Fi Issues

• Some performance tests (e.g. test_linearbandwidth.py) can occasionally fail in virtualized or non-quiescent environments due to performance variance, scheduling, or timing skew. Others may fail if they hit resource limits of the underlying system (e.g. a netbook or a VM with limited resources.)

• For the most accurate performance results, you may wish to run Mininet on a quiescent, non-virtualized environment.

Cluster Edition Prototype issues

• We do not currently recommend enabling ssh multiplexing (ControlPath feature) as we have observed problems with it.

• Additional information may be found on the Cluster Edition Prototype wiki page.

NAT warning!

The --nat option to mn can provide a convenient way to connect your Mininet network to your LAN or to the Internet.

Note however that mn --nat by design will reroute traffic originating at your Mininet server or VM and destined for Mininet's IP subnet (10.0.0.0/8 by default) to the Mininet network, which can break connectivity if you are using addresses in the same range in your LAN. You can change this range using the --ipbase option.

Errata

• Currently the Stanford Reference Switch (--switch user) and the CPqD switch (also --switch user if it is installed) do not correctly match MAC address 00:00:00:00:00:01. This means that they will not work with --mac or autoSetMacs=True.

• The Stanford Reference Switch (--switch user) has awful performance (kilobits per second rather than megabits) on some recent Linux kernels, including the one that we shipped in the Mininet 2.2.0 VM. We hope this can be fixed in the future. If you are experiencing this problem, we recommend using OVS or IVS if possible unless you are modeling a dial-up modem or ISDN.

• Currently NetworkManager may attempt to assign leases to the interfaces from a Mininet instance. This will cause an unwanted flood of DHCP requests, and your cpu usage to max out when Mininet is idle. To prevent this, stop NetworkManager with $ sudo stop network-manager.

• IPv6 keeps coming back, even though we try to disable it! Although it's good that IPv6 is now correctly virtualized, this means that the Mininet VM does not now disable IPv6 globally as intended. This means that unless you disable IPv6 in each Mininet host, you may see IPv6's irritating neighbor discovery packets. On the up side, it is now easier to use IPv6 in Mininet. If you wish to disable IPv6 permanently in your VM, edit the following line in /etc/default/grub:

      GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 text"
  

  then run

      sudo update-grub
  

  and reboot. IPv6 should be dead (finally?!)

• Currently --host rt may not work correctly when installed with apt-get install mininet on Ubuntu 12.04.5. The mininet package is missing the cgroup-bin dependency. To fix this, apt-get install cgroup-bin. Also see below.

• Currently --host rt will not work with any default Ubuntu kernel. The POSIX real-time scheduler has been disabled by default in all Ubuntu kernels. To fix this, enable RT_GROUP_SCHED in your kernel.

• Currently, the Mininet install.sh script seems to hang installing Mininet on Ubuntu 12.04.5 LTS (precise64, 64-bit); in particular, it hangs while installing/configuring cgroup-bin. This is obviously not a Mininet issue, but it's annoying. One workaround worth trying might be to install cgroup-bin before running install.sh.

• The intf class option to Mininet() is ignored. You can use the link option instead. Fixed in c5f6d0ff171.

Bug Reports and Support

You are encouraged to submit reports for any additional bugs you may encounter via github, and additional questions to the mininet-discuss mailing list. You may also edit these notes to fix errors or provide clarification.