Spring Security and multiple ldap configuration

I use Spring Security to manage user and group securities. All datas are stored in a ldap server. My configuration is the following: ``` <authentication-manager alias="authenticationManager"> <ldap-authentication-provider user-search-filter="(mail={0})" user-search-base="" group-search-filter="(uniqueMember={0})" group-search-base="ou=groups" group-role-attribute="cn" role-prefix="ROLE_" user-context-mapper-ref="contextMapper"> </ldap-authentication-provider> <lda </authentication-manager> <beans:bean id="contextMapper" class="com.mycompany.CustomContextMapper"> <beans:property name="indexer" ref="entityIndexer" /> </beans:bean> <ldap-user-service server-ref="ldapServer" user-search-filter="(mail={0})" /> <ldap-server manager-dn="cn=admin,dc=springframework,dc=org" manager-password="password" url="ldap://server/dc=springframework,dc=org" id="ldapServer" /> ``` All runs like a charm. Now, I want to add a second ldap server if the first one is down (fallback). I can't find an easy way to do it. So, my question si simple: how to add a second ldap server in this config to provide a fallback if the first one is down ?