Keeping NAS and RADIUS in sync

Hi, I have a few NAS servers (Mikrotik, PPPoE) using FreeRADIUS.

From time to time, maintenance, faults etc cause certain kinds of disruptions to the network which causes users to be disconnected from a NAS.

However, the NAS sometimes also loses access to the RADIUS server, so the stop accounting packet will never get through. This causes various problems for some tools we use. These tools work on the RADIUS SQL database and require the data to be accurate. Is there a recommended way of solving such cases? Thanks in advance. -- Vegard Svanberg <vegard@svanberg.no> [*Takapa@IRC (EFnet)]