Hi Harishita,
If you refer RFC - 3588 as the description says, the AVP is used when Result Code set to "DIAMETER_MULTI_ROUND_AUTH".
DIAMETER_MULTI_ROUND_AUTH explains:- that this informational error is returned by a Diameter server to inform the access device that the authentication mechanism being used requires multiple round trips, and a subsequent request needs to be issued in order for access to be granted.
Few more points I would like to add for this AVP, it is used with "Diameter Network Access Server Application".
So more details we can get from https://tools.ietf.org/html/rfc4005 Section 9.1 Page 55-58
Thanks,
Chinmoy