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Topology 2 is a "region aware" view of the topology, where the administrator can configure the network into regions and sub-regions.

In its default state (where no "regions" or "layouts" are defined), it should look and behave similarly to (and eventually the same as) the "classic" Topology view.

Note that this view is currently "experimental", although the longer term plan is to bring it up to par with the "classic" view, which it will eventually replace.

A more detailed description of the current state of Topology 2 can be found HERE. (Steven to provide link)


The ONOS model of the network includes Region objects which can be configured with a collection of Devices (switches) "belonging" to that region. 

Regions can be configured using a number of CLI commands:


To add a region to the model, the region-add command can be used..

region-add <region-id> <region-name> <region-type> <lat/Y> <long/X> <locType> <region-master>


  • <region-id> is a unique identifier for the region
  • <region-name> is a human readable name for the region
  • <region-type> is one of the values defined in the Region.Type enumeration:
  • <lat/Y>, <long/X> are the latitude / longitude (for geo layouts) or Y-coord / X-coord (for grid layouts) to be assigned to the region when it is displayed as a node in its parent layout.
  • <locType> is either geo (to indicate coords are lat/long) or grid (to indicate coords are Y/X).
  • <region-master> is a list of sets of node-IDs for mastership of the devices (see RegionAddCommand for more details).

A couple of examples:

region-add rUK "United Kingdom" COUNTRY 52.206035 -1.310384 geo " /"
region-add rRack1 "Primary Rack" RACK 15.0 20.0 grid

Note that CLI commands are scriptable. One way of doing this is as follows:

onos ${host} <<-EOF
region-add rUK "United Kingdom" COUNTRY 52.206035 -1.310384 geo ${host}
region-add rIT "Italy"   COUNTRY 44.447951  11.093161 geo ${host}
region-add rFR "France"  COUNTRY 47.066264  2.711458 geo ${host}


Devices can be assigned to regions with the region-add-devices command:

region-add-devices <region-id> <dev1> <dev2> ... <dev-n>


  • <region-id> is the region unique identifier
  • <dev-...> is a device identifier

For example:

region-add-devices rUK \
    of:0000000000000001 \
    of:0000000000000002 \    


The regions currently configured in the system can be listed with the regions command:

onos> regions
id=rDE, name=Germany, type=COUNTRY
id=rES, name=Spain, type=COUNTRY

Another region command we'll look at is region-add-peer-loc, but we'll defer that until we have covered layouts.

Note that regions do not have any notion of hierarchy; they are simply "collections of devices". The hierarchy is expressed using Layouts


Layouts are used to define a "containment" hierarchy for the regions, as well as provide configuration information for the UI, such as which background decoration to use when displaying the layout; for example a geographical map.

A Layout is a "UI construct" that has an associated region "backing" it. Layouts (except for the "root" layout) declare their parent layout, thereby defining a hierarchy of layouts to be constructed.

The following diagram illustrates an example hierarchy:

Note that the "root" (default) layout does not have a backing region. Any devices (and their attached hosts) that have not been assigned to a region will appear in the topology view at the top level.

Layouts can be configured using a number of CLI commands:


Layouts can be added to the model with the layout-add command.

layout-add <layout-id> <bg-ref> <region-id> <parent-layout-id> <scale> <offset-x> <offset-y>


  • <layout-id> is a unique identifier for the layout
  • <bg-ref> is a reference to the background to display for this layout
  • <region-id> is the identifier of the backing region
  • <parent-layout-id> is the identifier of the parent layout
  • <scale>, <offset-x>, <offset-y> are custom values to define the initial pan/zoom of the background

Some examples:

layout-add root @europe . . 4.66 -2562.93 -412.56
layout-add lUK @europe rUK root 11.63 -6652.54 -938.04
layout-add lIT @europe rIT root 7.15 -4818.73 -1330.36
layout-add lFR @europe rFR root 8.98 -5378.99 -1334.77

layout-add lMilan +segmentRouting rMilan lIT 0.86 68.58 54.71

Note the use of the dot (".") character in the definition of the root layout, as placeholders for the (non-existent) region-id and parent-layout-id.

Notes on <bg-ref>:

The <bg-ref> parameter should take the form:

    • "."            : to define no background,
    • "@{map-id}"    : to define a geo background, or
    • "+{sprite-id}" : to define a grid layout background

Map identifiers can be listed by using the ui-geo-map-list command in the onos CLI:

onos> ui-geo-map-list
UiTopoMap{id=australia, desc=Australia}
UiTopoMap{id=americas, desc=North, Central and South America}
UiTopoMap{id=n_america, desc=North America}
UiTopoMap{id=s_america, desc=South America}

Additional maps can be registered from an application's server-side UiExtension implementation. (link to tutorial needed)

Sprite identifiers can be listed by opening the web console, making sure verbose option is selected, and filtering for the string "createLayout":

Additional sprite layouts can be registered from an application's topology overlay JavaScript code. (link to tutorial needed)

Notes on <scale>, <offset-x>, <offset-y> values:

Currently, getting these values right is a manual process:

    • start by setting them to  1.0  0.0  0.0
    • enable debugging of UiWebSocket to see message transmissions between client and server
      • onos> log:set DEBUG org.onosproject.ui.impl.UiWebSocket
    • in the UI, pan and zoom the map to the desired location
    • in the log, identify the last UiWebSocket RX message for "updateMeta2"
      • 2017-05-26 17:07:15,750 | DEBUG | tp1445302012-173 | UiWebSocket                      
      • | 158 - org.onosproject.onos-gui - 1.11.0.SNAPSHOT | RX message: 
      • {"event":"updateMeta2","payload":{"id":"layoutZoom",
      • "memento":{"scale":4.66,"offsetX":-2560.646888427734,"offsetY":-409.13537841796875}}}
    • use the values listed in the "memento" field for your scripted command (you should be safe rounding to 4 decimal places)

One further note:

If the user zooms and pans a layout, the UI will remember how they left it.

However, by pressing the 'R' key, the view will reset to the <scale/offset> values configured in the layout-add command.


The layouts currently configured in the system can be listed with the layouts command:

onos> layouts
id=lDE, bgref=@europe, region=rDE, parent=root
id=lES, bgref=@europe, region=rES, parent=root
id=lFR, bgref=@europe, region=rFR, parent=root
id=lIT, bgref=@europe, region=rIT, parent=root
id=lMilan, bgref=+segmentRoutingTwo, region=rMilan, parent=lIT
id=lUK, bgref=@europe, region=rUK, parent=root
id=root, bgref=@europe, region=(root), parent=root

Putting this all together

View a brief demonstration of the UI configured with the regions-europe.sh script...

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