Actually NeXt support global geo map. Because of performance issue, I removed those from documentation but code is still there. Source code : next/WorldMapLayout.js at master · opendaylight/next · GitHub
And an example : World Map - JSFiddle
You need to do is register a WorldMap layout when topo is ready. and then use 'WorldMap' layout. You need to put the json file to you server.
topo.registerLayout('WorldMap', new nx.graphic.Topology.WorldMapLayout())
P.S. The performance of Global map is quite bad, so i have two different approach.
1. I use Canvas/WebGL to rendering the map. Zooming performance is quit good, but not fully developed yet. Once I finished, i will commit that to code repo.
2. Use leafletjs as an background. Not deep dive into this, if you are interested, we could work on this together.