Hi ,
We have recently upgraded 5 networks from MX15.44 to MX18.107 and I have noticed that the 802.1X re-auth timer ( was 3600s ) is now gone...
The MX doesn't support CoA so this was pretty much critical for us.
You can't 'shut /no shut' ports on a MX , so the default re-auth timer was pretty much magic.
A case is open , waiting on a reply.