SSO of EP with Microsoft portal

Hi Experts,

We have .net portal which is being authenticated through LDAP. Now there is also a link of my employee portal(EP) inside that.

Business wants me to do SSO between the two. Please help as requirement says that once user logins to that .net portal he or she should be able to acess employee portal(SAP EP) without entering user credentials.

We also authenticate our employee portal through the same LDAP.

Regards:

Sid.