amarsanaa,
as you report this problem for a
OES 1 server there might be a very great chance that your "SSL Certificates..." in edirectory for this server have expired. Did you ever check that via imanager ? If they are expired you need to create new one's and depending on the imanager version and plugins you are using you can do this in the certificate server roles and tasks. There might be an option to create default certificates. After that is done, the ldap server needs to be refreshed and you need to run "namconfig -k" to solve it.
Rainer