I enabled accounting and I am able to get the data but in most of the cases it says "RADIUS.Acct-Framed-IP-Address=null."
Below is the sample for the two logs with null and with an IP address !
eg:
Jun 17 08:36:02 X.X.X.X Jun 17 2015 08:36:00.922 EDT X.X.X.X CEF:0|Aruba Networks|ClearPass|6.5.0.71095|42133-1-0|Session Logs|0|TimestampFormat=MMM dd yyyy HH:mm:ss.SSS zzz RADIUS.Acct-Framed-IP-Address=null Common.Username=dc:86:d8:93:5c:45 Common.Request-Timestamp=2015-06-17 08:34:03-04 Common.Host-MAC-Address=dc86d8935c45 src=X.X.X.X
Jun 17 08:36:02 X.X.X.X Jun 17 2015 08:36:00.922 EDT X.X.X.X CEF:0|Aruba Networks|ClearPass|6.5.0.71095|42134-1-0|Session Logs|0|TimestampFormat=MMM dd yyyy HH:mm:ss.SSS zzz RADIUS.Acct-Framed-IP-Address=X.X.X.X Common.Username=dc:86:d8:93:5c:45 Common.Request-Timestamp=2015-06-17 08:34:03-04 Common.Host-MAC-Address=dc86d8935c45 src=X.X.X.X