A question about disconnections

[Nick Warr]

We're a WISP using freeradius to do our AAA, and are in the process of 
updating our backend to the latest version of freeradius (probably 
2.1.8), and we've been able to resolve a lot of issues with our current 
setup, except for a few (possibly vital) problems.

The one we haven't been able to find anything about is if there's a 
method, or check we can implement to prevent this sort of situation.

We have a central radius server, and a few point to point connections 
where we have our point to multipoint connections (base stations) each 
base stations is a NAS, which for the most part works just fine. Our 
problem happens if something interrupts the point to point connectivity, 
the PPP sessions between the CPEs and the base stations remain up, but 
on the radius side, if the point to point connection remains down for 
longer than the idle timeout, the user (at least for freeradius) is 
disconnected.

The NAS however, remains unaware of this (as the UDP disconnect message 
didn't arrive.. link down and all that), and the user remains up and 
functional, but we no longer have any accounting for that user. This of 
course, we can reset by hand, but if it happens during the night for 
example, we could lose several hours of accounting.

What I'd like to know is if freeradius 2.x has some sort of 
functionality we can configure to make sure that if the radius server is 
receiving accounting packets for an account which should be 
disconnected, that it will re-send the PoD to get the NAS to actually 
disconnect it.

Is what I'm requesting something strange (or conversely idiotic, because 
it's only our Mikrotik base stations that don't do something like this) ?


Thanks,

Nick Warr