Harshita, I have a very minimal information w.r.t this topic.
RAN Information Replay message sent over S3 interface, which is between SGSN and MME.
It's a bi-directional message, I mean to say it can be sent either by MME or by SGSN.
SGSN collects the RAN information from BSS and RNS, send to MME.
MME collects the RAN information from eNodeB and send to SGSN.