single sign on between subdomains in Mvc5

i want single sign on between subdomains...just like i am simple login to gmail account through useremail and pass and while click on youtube or any of the google product then there is no need to sign in once again.

The same way i need to implement in such a way that when i login xyz.com and in xyz.com i have a link of a.xyz.com,b.xyz.com this may be one sub domain or more then one sub domain ..they can access without login once again..(Here a.xyz.com or b.xyz.com are different project (web application) .

i have the userid and usercode and email .i need to pass or any other way so that i can access these three parameter which has in xyz.com.

i am using the in web.config in Mvc 5 c# so any blog sites available can any one ping me. where i can get some code and logic to implement.(All The project are in Mvc5)