802.1x EAP-PEAP log parsing

Couldn't find any references to this exact problem, so apologises if it actually has been talked about before. I'm trying to parse the auth-detail log files for 802.1x EAP-PEAP and trying to consolidate the inner authentication (from 127.0.0.1) with the outer authentication (from the real NAS), so I can generate log reports which include the real (inner) user name and real (outer) IP etc. etc. There is no obvious way of doing this, apart from the not-that-ideal method of time stamp matching. Is there something which can be derived from State or EAP-Message to match authentications up ? Is there another method ?