I am assuming that ldap_bind does a simple bind and that for other
types of bind, ldap_sasl_bind should be used.
Also, while the allow bind v2 solution will work with slapd, you really should
use ldap v3 if at all possible because of the security improvements and
better protocol definition. LDAP v2 is largely deprecated at this point.
Hopefully the PHP default LDAP version will move to v3 soon.