Ldap query

[Franks Andy (IT Technical Architecture Manager)]

Hi all,
  FR 3.1.0 64aa7f9
  I'm trying to get to the bottom of the ldap issues we're seeing with AD within freeradius. Basically when we take down one AD server (we have two sites, doesn't matter which it is), the ldap lookups from Freeradius have massive issues with timeouts, failure to bind errors etc. Now, I'd say this was an issue with AD, but we've tried this with various tools now, both linux and windows based, and we don't see any issues using, for example, ldapsearch, from the same server where FR is struggling.
Obviously I would love it if someone would say "oh yes, you need to change /etc/ldap/ ... " but that's not so likely, so I wanted just any information on what ldap libraries FR uses, whether some of the code is internal or not so I can start to try and find a solution as I'm guessing this will be a management reason to go towards clearpass.
Thanks!
Andy