What is a FIMAgentRefreshRequest and how is it scheduled?

The Event Broker 3.2.1.3 service is logging the following every 2 hours, but I don't have a corresponding schedule configured so I am thinking it must be built-in (???):

20170810,23:54:23,UNIFY FIM Event Broker,Agent Engine,Information,Scheduled job to perform a FIMAgentRefreshRequest on agent FIM Agent succeeded.,Normal

The reason I ask is that every day at the same time (and ONLY at this time) I am getting the following shortly afterwards (which happens to be just before the log rolls over):

20170810,23:54:33,UNIFY FIM Event Broker,OpenLDAPTriggerPlugIn.ResultsCallback.Error,Error,"System.DirectoryServices.Protocols:
System.DirectoryServices.Protocols.DirectoryOperationException: The server cannot handle directory requests.
   at System.DirectoryServices.Protocols.LdapPartialResultsProcessor.GetPartialResults(LdapPartialAsyncResult asyncResult)
   at Unify.Product.EventBroker.OpenLDAPListenPlugIn.ResultsCallback(IAsyncResult result)",Normal
...
20170810,23:56:42,UNIFY FIM Event Broker,OpenLDAPTriggerPlugIn.ResultsCallback.Error,Error,"System.DirectoryServices.Protocols:
System.DirectoryServices.Protocols.LdapException: The LDAP server is unavailable.
   at System.DirectoryServices.Protocols.LdapPartialResultsProcessor.GetPartialResults(LdapPartialAsyncResult asyncResult)
   at Unify.Product.EventBroker.OpenLDAPListenPlugIn.ResultsCallback(IAsyncResult result)",Normal

Every day for as long as the log files are retained, I get exactly the same sequence at almost exactly the same timestamps.

This is confusing because the agents all appear to be working fine for all of the dependent operations, with no errors reported that I can see otherwise.