[CentOS] redundant ldap - client config

Hi all,

I have a few ldap servers slaved to a primary via syncrepl, all is well.

I've set my clients to auth against a few and there /etc/ldap.conf  
looks like so;

uri ldap://primary.domain.com ldap://secondary.domain.com

However when either primary or slaves go down, while the clients can  
log in, access is very slow, ls of any dir is painful.

The /var/log/messages shows several failed attempts to conect to the  
slaves ldap servers.

Whats the proper way to set up redundant ldap on the clients?