random SERVER_DOWN exception during bind

[pipoun]

I randomly experience some exceptions during bind. I'm using the MetadataProvider class.
Here is a part of the traceback:

File "/home/install/tg2devenv/lib/python2.5/site-packages/repoze.who.plugins.ldap-1.1a1-py2.5.egg/repoze/who/plugins/ldap/plugins.py", line 421, in add_metadata
    raise ValueError( "Couldn't bind with supplied credentials. Exception : %s" % err.__repr__() )
ValueError: Couldn't bind with supplied credentials. Exception : SERVER_DOWN({'desc': "Can't contact LDAP server"},)

I've added "Exception : %s" % err.__repr__() in the code to have more info.
I'm using turbogears, if I refresh the page that raised the exception, everything is ok again.

I'm wondering:
- shouldn't unbind() be called after bind and lookup operations ?
- why bind isn't called just once in make_ldap_connection ?

Thanks!

[pipoun (pipoun)]

I have omitted to add that I'm connecting to an Active Directory server.

Moreover, from the doc:
http://www.python-ldap.org/doc/html/ldap.html#ldap.LDAPObject.unbind_ext_s
Once an unbind() is called, the connection has to be initialized again.
So, indeed unbind should be called in the add_metadata method

Would it be perhaps a timeout issue?

[pipoun (pipoun)]

"should *not* be called" sorry for the typo!