FlowVisor is a specialized OpenFlow controller that creates slices within an OpenFlow network, allowing the same physical deployment to support multiple controllers. Here we describe the setup/installation FlowVisor 0.8.3 on Ubuntu 11.04.


There are two main sections. The first describes how to set up and run FlowVisor; The second describes some details about how the code functions and is probably more useful for development.

  1. General setup and usage
  2. Architecture and implementation details



The latest FlowVisor is based on java, requiring the following packages:

apt-get install ant sun-java6-jdk

It is assumed that you have OpenFlow installed and in working condition.


The installation process has gotten very streamlined compared to the 6.0 days. Refer to older versions of this page to see how it is done for version 6.* of flowvisor.
A flowvisor user may be created as the admin user for flowvisor (e.g. running fvctl). This will come into play during the install when you are prompted to specify a flowvisor user/group.

  1. install above-mentioned packages
  1. pull from mercurial repository:
    hg clone
    hg update -C 0.8-MAINT

the update command is equivalent to a git checkout and puts us on the (most recent stable) flowvisor-8.3 branch.

  1. run make and make install. The make install process will prompt you with several questions:
native@ubuntu:~/flowvisor$ make install
Buildfile: /home/native/flowvisor/build.xml


    [javac] /home/native/flowvisor/build.xml:34: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds


Installation prefix (/usr/local):     
FlowVisor User (needs to already exist) (native): 
FlowVisor Group (needs to already exist) (native): 
Install to different root directory () 
Installing FlowVisor into /usr/local with prefix=/usr/local as user/group native:native


Enter password for account 'fvadmin' on the flowvisor:
Generating default config to /usr/local/etc/flowvisor/config.xml
--- 'flowvisor!logging' not set in config; defaulting to loglevel 'NOTE'
--- Setting logging level to DEBUG
  1. Generate a default configuration file:
    fvconfig generate /usr/local/etc/flowvisor/flowvisor-config.json

Now your install should be ready to run.


the primary means of configuring flowvisor is via fvctl.Unlike older versions of nox, you don't need to create configuration scripts, which is great. Here, we'll describe how to use fvctl through an example run based on the flowvisor webpage.

The testrun Setup

In this setup, FlowVisor is started on port 6655, with an instance of nox listening on port 6656. A FlowVisor slice is created to listen to any controllers using port 6656 (in this case, our test NOX instance). A single virtual switch was made to listen for controllers on port 6655, whereby its control is given to NOX by flowvisor. Everything, unless specified, is done in the flowvisor directory.

  1. start FlowVisor. Unlike nox, there are no flags to throw it into the background. Here it is started on port 6655:
    flowvisor -p 6655 &

flowvisor has several options, although config.xml is now irrelevant:

r$ flowvisor -v
Starting FlowVisor
FlowVisor version: flowvisor-0.8.3
Rob Sherwood:
err: ParseException: org.openflow.example.cli.ParseException: unknown option: v
FlowVisor [options] config.xml
        option        type [default]      usage
        -d|--debug    String [NOTE]       Override default logging threshold in config
        -p|--port     Integer [0]         Override port from config
        -l|--logging                      Log to stderr instead of syslog
        -j|--jetty portInteger [-1]        Override jetty port from config
        -h|--help                         Print help
  1. delete sample slices. After inspecting them with getSliceInfo, remove them with deleteSlice. There are two slices, "alice" and "bob". Each action usually requires authentication using the password you created in step 1.
    fvctl getSliceInfo alice 
    fvctl deleteSlice alice 
    fvctl getSliceInfo bob 
    fvctl deleteSlice bob 
  1. create your slice. This is done via createSlice. The syntax goes roughly like this:
    fvctl createSlice <slice name> tcp:<controller's ip>:<controller's port> <your email>

So for our example, we have a slice "nox-test," which expects a controller with ip living on port 6656:

fvctl createSlice nox-test tcp:
  1. create your flowspace. Flowspaces define the policy for your slices. Many parameters can be tacked onto addFlowSpace:
    fvctl addFlowSpace all <priority number> <policy> "Slice:<slice name>=<permissions>"
  • priority - a number between 0 and 231. Higher value = higher priority
  • policy - flow matching policies. Details are under FLOW SYNTAX in the fvctl(1) man pages.
  • slice name - the name of your slice.
  • permissions - similar to chmod, with delegate=1, read=2, write=4.

What we want is very minimal: allow all for the controller of the slice:

fvctl addFlowSpace all 1000 any "Slice:nox-test=7"
  1. start the controller. Start nox on the IP:port combination defined for the controller in the FlowVisor slice:
    ./nox_core -i ptcp:6656 switch packetdump -d
  1. start virtual switch. Here we instantiate an IP8800 switch with a virtual switch listening to FlowVisor, which is
    setvsi 22 37,38 tcp dpid 0x001010223232

The datapath should come up as "connected" under showswitch.

Moving controllers to slices

Here are the steps used to actually move the ORBIT infrastructure to a FlowVisor slice.

  1. edit default port for noxcore. The default settings for snac (e.g. what port it uses, ect) is found in /etc/default/noxcore. Edit the port it uses for the control channel from 6633 to the new port:
     OF_LISTEN="-i ptcp:6634"
  1. start flowvisor and set up slices:
     flowvisor config.xml 6633 &
     fvctl createSlice orbit-snac tcp:
     fvctl addFlowSpace all 10000 any "Slice:orbit-snac=7"
  1. restart snac:
     /etc/init.d/noxcore restart

FlowVisor should now be managing the slice for SNAC.

Some notes on architecture and implementation.

In general, FlowVisor is well-documented (see refs link at top of page). This section describes some more in-depth implementation details of FlowVisor (currently 0.8.3).

Event handling

Event handling is done by registering handlers with a loop construct (FVEventLoop). Handlers are implementations of the FVEventHandler interface. Handlers include core FlowVisor components such as OFSwitchAcceptor, FVClassifier, and FVSlicer. The overview of the relationship between these components can be found here.

Events are FVEvent-derived classes, with FVEvent being the base unit for passing events between event handlers. They come in several categories, including:

  • FVIOEvent - a new incoming OpenFlow message
  • OFKeepAlive - an OpenFlow ECHO_REQUEST
  • TearDownEvent - shutdown of FlowVisor components
  • FVRequestTimeoutEvent - a timer has expired

Some things with 'event' in their names, such as UnhandledEvent, may represent an exception.


Main function:

  1. Read configurations from file (default: /usr/local/etc/flowvisor/config.json)
  2. Populate FVConfig with file contents
  3. launch run() routine

run() routine:

  1. Instantiate event loop
  2. If the topology controller is needed, initialize
  3. Initialize the OFSwitchAcceptor
  4. Initialize the API server
  5. Set configurations with contents of FVConfig
  6. launch event handling

In OFSwitchAcceptor:

  1. Initialize socket select to listen for incoming connections
  2. If event doesn't stem from the current thread context (e.g. the Acceptor itself), enqueue to be processed by other components.
  3. Else, if incoming connection is an FVIOEvent, spawn an instance of FVClassifier

In FVClassifier:

  1. Send controller side of OpenFlow handshake (Hello, features request). The initial process also pushes a flow mod that causes switches to drop all, until further flow information can be acquired.
    2.For each event:
    1. Classify the type of event
    2. check if message is from a new or previously known switch (check switchInfo, a structure that holds an OFFeatureReply for the switch this classifier is associated with)
      • if known switch, call classifyFromSwitch, the appropriate handler for the message (defined by the message itself as part of the Classifiable interface)
      • if not (and message is a FEATURES_REPLY), fetch a copy of the flow map, and from it, a list of slices associated with the switch's DPID (the list is stored in a classifier's newSlices list). The information is fetched withthe aid of FlowSpaceUtil's functions that query the flow space.
      • for each slice in newSlices, spawn a FVSlicer if slice does not already have a slice (e.g. an entry in slicerMap, a map of slice names to active FVSlicer instances)
      • update slicerMap with contents of newSlices

In FVSlicer:

(to-be completed in detail)

  1. Attempt to connect to controller, sending Hello
  2. handle messages with sliceFromController

Last modified 11 years ago Last modified on Jun 21, 2012, 9:40:40 PM
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