3D Tiles : tile refreshed/reloaded all the time, how to control it ?


I am building a set of datas in B3DM format with a minimal tileset definition.

The problem I have is cesium reloads the tiles all the time.
This eats up a lot of bandwidth and with multiple tiles it get extremly slow.

I have try to play with various header parameters :
etag, cache-control, age, expires, ...
without success.

Question is :
What are the conditions/parameters/headers to control 3d tiles refresh rate ? or how to disable it completely ?

The spec doesn't tell anything about it.


--------------------- Context ------------
Cesiumjs : 1.45