My client ironport was configuring to use port 389 to connect the DC.
One day few weeks ago its stop working….
I receive error msg that the ironport cant connect in 389 port.
I have changed the port number to 3268 and everything was back to normal.
2 hours after another client (company) called me with the same problem.
I change his LDAP port to 3268 and everything was back to normal.
What is the chance to this happened in two different client in the same day?
And still I get sometimes msg like this:
LDAP: work queue processing error in abcd_AD.accept reason [Errno 54] Connection reset by peer (1.2.3.4:3268)
(I have change the real ip address ….)

* sorry for my English….