ldap server does not offer SASL/EXTERNAL mechanism

Issue

• OpenLDAP server returns the following error when trying to use slapi interface to connect to ldap server using EXTERNAL mechanism. Tried to find the mechanisms available lists only GSSAPI.

# ldapsearch -Y EXTERNAL -b "" -s base -H ldapi:/// supportedsaslmechanisms
SASL/EXTERNAL authentication started
ldap_sasl_interactive_bind_s: Authentication method not supported (7)
        additional info: SASL(-4): no mechanism available: security flags do not match required
# ldapsearch -x -H ldapi:/// -b "" -LLL -s base supportedSASLMechanisms
dn:
supportedSASLMechanisms: GSSAPI