bind/queries through multiple backends

[Steffen Kaiser <vm5015995887542392v@vmail.inf.h-brs.de>]

Hi,

I currently have a local OpenLDAP v2.4.40 with a bdb backend and another 
instance with a ldap backend proxying binds and queries to an AD.

The bdb backend serves just one suffix:

dc=example,dc=com

The AD serves several suffixes:

dc=example,dc=com (same as local one)
dc=example,dc=net
dc=otherexample,dc=com
dc=anotherexample,dc=net

I would like to merge both configurations.

The entries of the suffix dc=example,dc=com, which is served by both 
servers, are disjunct. There is no DN, which is located on both servers. 
There will be some name problems, but these can be handled by 
organisational means.

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My first problem is that I cannot make bind work for DNs with 
suffix dc=example,dc=com, which are located on the 2nd backend. In fact, 
there are very few DNs of that suffix on the 2nd server, but there are. I 
would like that bind first tries the first (local) server and, if the DN 
is missing there, the second server (the proxy).

Currently, only the local backend is queried.

====

What would be the best solution to forward a bunch of suffixes to the LDAP 
backend?

--
Steffen Kaiser