Hii ...
I have setup a simple machine forum, and create my ownwebsite. I want to Integrate Authentication my website with simple machine forum. the authentication handled in SSI.php that a part of simple machine forum function.
I host my own webiste and the simple machine forum in different address. supposed I host my website host in www.ownweb.com and the simple machine forum in www.smf.com.
Can you have suggestion how to do solve this problem ?

You can't! Cookies and sessions are NOT cross-domain never mind cross-servers.

Cross server is possible by storing the session in a DB rather than the local machine.

However.
Ive never tried cross domain.

It works for load balancing users ( they can swap from server to server ) and still keep their session.

Oke .., thanks for your explanation