Mininet Sample Workflow

Mininet Sample Workflow

Mininet enables you to quickly create, interact with, customize and share a software defined network prototype, and provides a smooth path to running on hardware. This page illustrates the basic Mininet workflow, and many additional details are available in the Mininet walkthrough, the OpenFlow tutorial, and Mininet documentation.

 

Creating a Network

You can create a network with a single command. For example,

sudo mn --switch ovs --controller ref --topo tree,depth=2,fanout=8 --test pingall

starts a network with a tree topology of depth 2 and fanout 8 (i.e. 64 hosts connected to 9 switches), using Open vSwitch switches under the control of the OpenFlow/Stanford reference controller, and runs the pingall test to check connectivity between every pair of nodes. (This takes about 45 seconds on my laptop.)

 

Interacting with a Network

Mininet’s CLI allows you to control, and manage your entire virtual network from a single console. For example, the CLI command

mininet> h2 ping h3

tells host h2 to ping host h2’s IP address. Any available Linux command or program can be run on any virtual host. You can easily start a web server on one host and make an HTTP request from another:

mininet> h2 python -m SimpleHTTPServer 80 >& /tmp/http.log &
mininet> h3 wget -O - h2

 

Customizing a Network

Mininet’s API allows you to create custom networks with a few lines of Python. For example, the following script

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from mininet.net import Mininet from mininet.topolib import TreeTopo tree4 = TreeTopo(depth=2,fanout=2) net = Mininet(topo=tree4) net.start() h1, h4 = net.hosts[0], net.hosts[3] print h1.cmd('ping -c1 %s' % h4.IP()) net.stop()

creates a small network (4 hosts, 3 switches), and pings one host from another (in about 4 seconds with the current version.)

The Mininet distribution includes several text-based and graphical (see above) applications which we hope will be instructive and inspire you to create cool and useful apps for your own network designs.

 

Sharing a Network

Mininet is distributed as a virtual machine (VM) image with all dependencies pre-installed, runnable on common virtual machine monitors such as VMware, Xen and VirtualBox. This provides a convenient container for distribution; once a prototype has been developed, the VM image may be distributed to others to run, examine and modify. A complete, compressed Mininet VM is about 1GB. (Mininet can also be installed natively - apt-get install mininet on Ubuntu.) If you are reading a great SIGCOMM (or other) paper about a Software-Defined Network, wouldn’t you like to be able to click, download and run a living, breathing example of the system? If so, consider developing a Mininet version of your own system that you can share with others!

 

Running on Hardware

Once a design works on Mininet, it can be deployed on hardware for real-world use, testing and measurement.

To successfully port to hardware on the first try, every Mininet-emulated component must act in the same way as its corresponding physical one. The virtual topology should match the physical one; virtual Ethernet pairs must be replaced by link-level Ethernet connectivity. Hosts emulated as processes should be replaced by hosts with their own OS image. In addition, each emulated OpenFlow switch should be replaced by a physical one configured to point to the controller. However, the controller does not need to change. When Mininet is running, the controller 「sees」 a physical network of switches, made possible by an interface with well-defined state semantics.