Not aware that NA functions can be applied in CE so far. Not sure if it will be available in CE.
Generally, if the route /graph data analysis is required in the app, the City model should be imported into ArcGIS (with NA), including desktop, Pro, or server of ArcGIS, from CE.
While the ArcGIS network analysis tools themselves do not exist in CityEngine, some network analysis tools do exist CityEngine that can analyze the Global Integration, Local Integration, and Inbetween Centrality of a network and allow a user to base design decisions on that information. To be clear this is a very limited set of metrics, and not as robust as NA because they are segment based calculations and not capable of any other network operations (such as service area calculation,routing, or others). *
If you want to make design decisions on roads or buildings in CityEngine based on an analysis you did in ArcGIS using NA or other extensions* you have two main options:
Summarize Analysis Results to Attributes in Imported Base Shapes: This means depending on the results of your analysis on buildings or street segments, make sure the imported data has attributes determined ahead of time.
Shape Sampling from the Analysis: Either sample data from overlapping shapes or a raster layer. This can be traffic volumes, transit accessibility maps, service areas, or even residential density rasters. Check out the details for sampling though.
For more information on Map Layers check the Help documents.
I hope this is somewhat helpful.
The concepts of street network and graph network in CE are not the same as NA in GIS.
In other word, the functions of street network and graph network in CE are basically not used to find the optimal /shortest route between two locations.
For various network analyses or route analysis in ArcGIS, refer to tutorial at ArcGIS Help (10.2, 10.2.1, and 10.2.2)
I have edited my response to be more specific. I understand that it is not used to find the shortest path between two points, but if someone is using CE I was assuming they might be interested in potential workflow integration between ArcGIS and CE.