This Jira aims to add the capability to NameNode to run additional listener(s). Such that NameNode can be accessed from multiple ports. Fundamentally, this Jira tries to extend ipc.Server to allow configured with more listeners, binding to different ports, but sharing the same call queue and the handlers. Useful when different clients are only allowed to access certain different ports. Combined with
HDFS-13547, this also allows different ports to have different SASL security levels.