In Ubuntu, we've applied the attached patch to achieve the following:
[ Thierry Carrez ]
* debian/rules: Enable -DLDAP_CONNECTIONLESS to build CLDAP (UDP) support
in the openldap library, as required by Likewise-Open (LP: #390579)
We thought you might be interested in doing the same.
See https://bugs.launchpad.net/ubuntu/+source/openldap/+bug/390579
I'm concerned by the need to set this via CFLAGS. It may not have performance or stability consequences (cf. the LP bug), but why is it not exposed via ./configure?
UDP support is non-standard. There is no specification for it in LDAPv3 and there never will be. Since there is no formal specification of how it should function, there is no way to claim it works (correctly or not) therefore it is officially unsupported.