unified communication multi-sites

hello all,

I want to make a multi sites unified communication. for now, i did it for one site(AD,Exchange,Lync). i desire to perform it and make a communication between two sites(AD1 and AD2 for example). does it suppose that i have tp make one more time all the platforme for an other (AD2,Exchange2,Lync2)? if yes, after that what i have to do? 

give me some advices please and if you have tutorials.

thanks ;)

Best regards