Detecting Session Timeout and Redirect to Login Page in ASP.NET

In this example i'll show how to detect the session timeout which occurs when user is idle for the time specified as Session.Timeout,using C# asp.NET and if it is than redirect the user to login page to login again, for this i've set time out value in web.config file to 1 minute I've created three pages in this example , one is login page , when session expires , i redirect to this page , one is navigation page where i'll check if session is valid or not , if it is valid than only user will see this page other wise he gets redirected to login page