You need to configure your application to maintain session state across multiple web servers.
When the data stored in session is easy to recreate or is not critical, configure your application to use the ASP.NET State Service using the following steps:
Set up a new server with the .NET Framework installed to maintain session state on behalf of your application.
Start the ASP.NET State Service on the designated machine.
mode attribute of the
<sessionState> element of the application
web.config file on its current web server to
specify the ASP.NET State Service.
Copy the contents of the root folder and subfolders of your application on the current web server to the additional web servers.
When it is critical to not lose any session information if server problems arise, use SQL Server to store all session information, as follows:
In the instance of SQL Server that you will use for this purpose,
install the special tables and stored procedures that ASP.NET
requires by running the
provided with the .NET Framework.
Set up a database user with read/write access to the
web.config file, as shown next,
setting the IP address to the address of your SQL Server machine and
pwd with the settings for the database
user with read/write access to the
sqlConnectionString="data source=10.0.1.12;user id= ...