RBF(Router Based Federation) shipped in 3.0+ and 2.9..
now its out various corner cases, scale and error handling issues are surfacing.
And we are targeting security feaiure (HDFS-13532) also.
this umbrella to fix all those issues and support missing protocols(HDFS-13655) before next 3.3 release.
RBF: Adding security
RBF: Add missing ClientProtocol APIs to RBF
Router-based HDFS federation phase 2
Über-JIRA: HDFS RBF stabilization phase II